Psychophysiological arousal in older adults: a critical review

Clinical Psychology Review, Vol. 21, No. 4, pp. 609±630, 2001 Copyright D 2001 Elsevier Science Ltd. Printed in the USA. All rights reserved 0272-7358/01/$ ± see front matter

PII S0272-7358(00)00052-0

PSYCHOPHYSIOLOGICAL AROUSAL IN OLDER ADULTS: A CRITICAL REVIEW Angela W. Lau, Barry A. Edelstein, Kevin T. Larkin West Virginia University ABSTRACT. In spite of the relatively high prevalence rates of anxiety disorders (AD) and related symptoms, very little is known about the experience, presentation, and assessment of anxiety in later life. Because the physiology of the autonomic nervous system changes with age, an enhanced understanding of how these developmental changes affect the somatic ± physiological response patterns to anxiety-evoking stimuli among older adults may help explain whether we can generalize current assessment and treatment practices and procedures for AD from younger to older adults. In this paper, we describe and critically evaluate studies that have employed psychophysiological recording of autonomic arousal to anxiety-arousing or stressful stimuli among samples of younger and older adults. The conclusions one can draw from the review are quite limited by both the paucity of relevant literature and the methodological limitations of the published studies. D 2001 Elsevier Science Ltd. All rights reserved. KEY WORDS. Older adults, Psychophysiology, Assessment, Anxiety disorders, Heart rate, Blood pressure, Electrodermal activity. THERE ARE APPROXIMATELY 33.2 million older adults (65+ years) in the United States, and approximately 23% of these meet diagnostic criteria for mental disorders (Gatz, Kasl-Godley, & Karel, 1996). Anxiety disorders are among the most prevalent of these disorders (Regier et al., 1988). The Epidemiological Catchment Area Survey revealed a 1-month prevalence rate of anxiety disorders in older adults of 5.5% (Regier et al., 1988). Bland, Orn, and Newman (1988) reported similar findings from an epidemiological survey of three communities in Canada. The results of the Epidemiological Catchment Area Wave II survey confirmed a prevalence rate of 4.8% for generalized anxiety disorder in older adults (Blazer, George, & Hughes, 1991). It is possible that these reported prevalence rates for anxiety disorders in older adults may be underestimated, as none of these surveys included diagnoses of posttraumatic stress disorder (PTSD). In addition to investigations of prevalence of diagnosable anxiety conditions, approximately 13% (Magni & De Leo, 1984) to 40% (Magni, Schifano, deDominicis, & Belloni, 1988) of community-dwelling and hospi-

Correspondence should be addressed to Dr. Angela W. Lau, VA Palo Alto Health Care System, 3801 Miranda Avenue (116 B), Palo Alto, CA 94304. Phone: (650) 493-5000, ext. 63524. Fax: (650) 852-3445; E-mail: [email protected] 609

610

A.W. Lau et al.

talized older adults have reported experiencing anxiety symptomatology sufficient to warrant clinical intervention, even though they did not meet full criteria for an anxiety disorder. In spite of the relatively high prevalence rates of anxiety disorders and related symptoms, very little is known about the experience, presentation, and assessment of anxiety in later life (Kogan, Edelstein, & McKee, 2000). Congruent with the literature examining anxiety among children and young adults, the experience of anxiety in older adults can also be described and assessed using Lang's (1968) three response systems, including overt ± motor, verbal ± cognitive, and somatic ± physiological responses. According to Lang, although related to one another, each response system is partially independent. That is, each response system can influence one another, but ``none of these systems hold a special controlling relationship to the others'' (Lang, 1968, p. 90). Thus, a comprehensive understanding of anxiety and its disorders for a person of any age requires the description and assessment of all three response systems (Cone, 1979; Lang, 1968; Turpin, 1991). Although arguments have been made that our assessment of all anxiety response systems is inadequate for older adults (Kogan et al., 2000), this paper will focus on the evaluation of research examining the somatic± physiological response system among older adults. There are several reasons for examining the somatic± physiological responses associated with anxiety in older adults (cf. Turpin, 1991). First, physiological arousal is considered a causal factor in several theories of anxiety acquisition and maintenance for persons of all ages (Barlow, 1988; Forsyth & Eifert, 1996; Mower, 1939; see Lader & Marks, 1971). Second, physiological measures of autonomic arousal can aid in the classification and diagnosis of anxiety disorders, as arousal is a ubiquitous symptom of anxiety disorders in all ages (Papillo, Murphy, & Gorman, 1988; Zuckerman, 1991). Moreover, individuals with various anxiety disorders react differently to phobic stimuli than individuals without anxiety disorders (see Barlow, 1988 for a review), and individuals with different types of anxiety disorders (i.e., social phobia, specific phobia, agoraphobia, mixed anxiety ± depression) exhibit differences in skin conductance responses and habituation to arousing stimuli (e.g., Lader, 1967). Third, physiological measures have been helpful in treatment planning and monitoring treatment progress. Physiological assessment can help in initially identifying target behaviors by identifying those that evoke the greatest physiological responses from a client (e.g., Abel, Blanchard, Barlow, & Mavissakalian, 1975; Turpin, 1991). As treatment progresses, repeated physiological assessment can be used to document treatment outcome, corroborating self-reported measures of behavior change. Though assessment of the somatic ± physiological anxiety response domain is important for a variety of reasons noted above, there are no published studies of the physiological assessment of anxiety among older adults with anxiety disorders. This is a problem for those wishing to use physiological assessments of anxiety among older adults, as age-related changes in human physiology over the lifespan could dramatically alter the nature, presentation, and experience of anxiety among older adults. For example, as an individual ages, arteries become less plastic, leading to greater peripheral resistance (Lakatta, 1990). In addition, weakened cardiac muscles result in decreased efficiency in blood circulation (Lakatta, 1990). Developmental changes also occur in the electrodermal system (Porges & Fox, 1986). As one ages, the density of sweat glands diminishes, the number of active eccrine sweat glands decreases, and the active sweat glands produce smaller amount of sweat than before

Psychophysiological Arousal in Older Adults

611

age 65 (Catania, Thompson, Miachalewski, & Bowman, 1980; Montagna, 1965; Porges & Fox, 1986). If the physiology of the autonomic nervous system changes with age, it is essential to understand how these changes affect the somatic ± physiological response patterns to anxiety-evoking stimuli among older adults with and without anxiety disorders. An enhanced understanding of developmental changes in the somatic ±physiological response system may help explain discrepancies in anxiety disorder prevalence rates between older and younger adults and whether we can generalize current assessment and treatment practices and procedures for anxiety disorders from younger to older adults. In this paper, we describe and critically evaluate studies that have employed psychophysiological recording of autonomic arousal to anxiety-arousing or stressful stimuli among samples of younger and older adults. As stated above, because no studies have examined older adults diagnosed with anxiety disorders, the participants in all studies reported here were not clinical patients with anxiety disorders. We will focus on the most commonly used measures of autonomic arousal found in the research and clinical practice literature (i.e., heart rate, blood pressure, electrodermal activity; Anderson & McNeilly, 1991; Fredrickson, 1991; Turpin, 1991). Another reason for focusing on these dependent measures is that they are associated with the somatic ±physiological symptom most commonly reported with anxiety (e.g., racing heart, pounding heart, sweaty palms). Only studies that met the following criteria were included: (1) dependent measures included heart rate, blood pressure, and/or electrodermal activity; (2) a nonpharmacological stressor was utilized in the experimental condition; (3) the sample included adults over the age of 60 as well as adults under the age of 60 for comparison purposes; and (4) statistical analyses contrasting younger and older participants were conducted on the physiological measures. Twenty published studies were found that met these criteria. Although some of the studies also investigated other physiological measures (e.g., blood plasma levels), we only considered the portions of each study related to heart rate, blood pressure, and electrodermal activity measurements.

DESCRIPTION OF THE STUDIES Of the 20 published studies, 4 employed classical conditioning procedures (Botwinick & Kornetsky, 1960; Shmavonian, Yarmat, & Cohen, 1965; Shmavonian, Miller, & Cohen, 1968, 1970), 14 employed a mental stressor task (Barnes, Raskind, Gumbrecht, & Halter, 1982; Boutcher & Stocker, 1996; Capriotti, Garwood, & Engel, 1981; Ditto, Miller, & Maurice, 1987; Faucheux, Bourleire, Baulon, & Dupuis, 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, Baulon, Lille, & Bourliere, 1983; Furchtgott & Busemeyer, 1979; Garwood, Engel, & Capriotti, 1982; Jennings, Brock, & Nebes, 1990; Morris & Thompson, 1969; Levenson, Carstensen, & Gottman, 1994; Powell, Milligan, & Furchtgott, 1980; Silverman, Cohen, & Shmavonian, 1958), and 4 employed a physical stressor task (Capriotti et al., 1981; Eisdorfer, Doerr, & Follette, 1980; Garwood et al., 1982; Norris, Shock, & Yiengst, 1953); two studies examined both mental and physical stressors. See Table 1 for a summary of the studies. The classical conditioning studies paired electrical shock with a tone and investigated age differences in the acquisition and extinction of physiological responses to electrical shock. Mental stressor tasks involved provocation by a psychological

30M: 15M (A = 20.9); 15M (A = 58.8)

Boutcher & Stocker (1996)

SCL

Stroop task

HR Current medical BP pathology, CVD; ``confounding'' medication use; history of aerobic training and smoking in last 5 years; poor peripheral circulation; abnormal cardiac function; compatibility with recording device SCL Thyroid disorders; diseases that alter adrenal cortical activity; taking diuretics

GSR: O fewer trials to extinguish than Y during adaptation and during extinction period; O fewer/ smaller responses during conditioning period HR: Y greater reactivity to stimulus presentation than O; O higher baseline level than Y. SBP: O higher baseline level than Y. DBP: O higher baseline level than Y

HR: Y greater reactivity to stimulus presentation than O

Measure(s) with Age Effects

Mental arithmetic; incongruous slide; time estimation

SCL: Age  Recording Site interaction

Mental arithmetic; time None estimation; cold pressor; isometric exercise; incongruous slide

Shock-tone

GSR

Not reported

Digit span; serial subtraction

Stressor task(s)

HR BP (MAP)

Physiological measure(s)

Chronic or acute illness

Exclusionary criteria

Capriotti et al. 52M, participants in (1981; Exp. 1) the BLSA: 24M (age 30 ± 47; A = 40); 18M (age 48 ± 65; A = 56); 10 M (age 66 ± 82; A = 71) (Exp. 2) 38M: 17M (age 30 ± 47; A = 38); see Capriotti et al. (1981; Exp. 1) 17M (age 48 ± 65; A = 56); 14M (age 66 ± 82; A = 72)

Botwinick & Kornetsky (1960)

20M: 10M (age 23 ± 33; A = 26.6); 10M (age 64 ± 74; A = 68.5) 48M: 9M ``religious volunteers'' (A = 20); 39M from NIMH research pool (A = 72)

Participant characteristics

Barnes et al. (1982)

Study

TABLE 1. Summary of Psychophysiology Studies

612 A.W. Lau et al.

Participant characteristics

Exclusionary criteria

Ditto et al. (1987)

CVD; medication 42F: 20F students that could affect (age 17 ± 28; A = 22.5); cardiovascular 22F retired, communityresponding; poor dwelling (age 60 ± 96; A = 78) health None reported Eisdorfer 20 ± 29; A = 23.6); et al. (1980) 17M (age 40 ± 49; A = 46.4); 17F (age 40 ± 49; A = 51.5); 15M (age 65 ± 75; A = 70.8); 13F (age 65 ± 75; A = 70.3) Cardiac, renal Faucheux 48M, management staff insufficiency; MI; CVD; et al. (1981) recruited from files of a mental disorders; pension fund: 24M drug addiction; use of (age 51 ± 55; A = 52.9); b-blockers, a-methyldo24M (age 71 ± 74; A = 72.3) pa, clonidine, reserpine, AD see Faucheux et al. (1981) See Faucheux et al. Faucheux, (1981) Baulon, et al. (1983) See Faucheux et al. 27M, management staff from Faucheux, (1981) files of a pension fund: Dupuis, 10M (age 51 ± 55; A = 53.4; et al. (1983) 17M (age 71 ± 74; A = 72.3) Use of AD or ANS 67M, Baltimore Gerontology Furchtgott & stimulant medication Research Center staff and Busemayer participants in the BLSA; (1979) 23M (age 23 ± 29; A = 31); 16M (age 40 ± 59; A = 49.5); 28M (age 80 ± 87; A = 73.5)

Study

Benton visual retention test; concrete object visual retention test; Rey word-learning test; digit symbol coding; See Faucheux et al. (1981) See Faucheux et al. (1981) Mental arithmetic; learning task

HR HR

HR EDA

Serial subtraction; imagining anxietyprovoking situation; imagining angerprovoking situation Valsalva maneuver

Stressor task(s)

BP

EDA

HR BP

Physiological measure(s)

HR: Y greater reactivity to stimulus presentation than O; Y greater reactivity only to certain task(s) HR: Y higher HR during math instructions but not during task; Y greater reactivity only to certain task(s); O slower recovery to baseline than Y. EDA: Y higher basal level than O

HR: O slower to recovery to baseline than Y

SBP: O higher baseline level than Y; O greater reactivity to stimuli than Y

HR: Y greater reactivity to stimulus presentation than O; Y higher baseline than O. SBP: O higher baseline than Y. DBP: O higher baseline level. SCL: Y more reactive to stimulus than O. SCR: Age  Sex interaction

Measure(s) with Age Effects

Psychophysiological Arousal in Older Adults 613

HR SCL

HR BP

Physiological measure(s)

Poor health; drug use; Jennings et al. 30M: 15M students < 12.5 years of educa(1990) (age 18 ± 26; A = 22); tion; medication that 15M community-resident can influence CNS or volunteers (age 60 ± 79; ANS function A = 69.5) Age not between 40 ± 50, Levenson 151 couples, from list of et al. (1994) licensed drivers and registered 60 ± 70; > 5 years age voters; 85.9% Caucasian, 5.8% difference between spouses; primary wage Black, 2.6% Hispanic, 2.6% earner retired; middleAsian, 2.2% Biracial; 79 couples (age 40 ± 50; A: M = 44; aged couples married F = 43); 72 couples (age 60 ± 70; < 15 years; old couples married < 35 years; reA: M = 63; F = 62) side farther than 10 miles from UC Berkeley campus; alcoholism; ESL; >20 point difference on MSS; not cohabitating

Exclusionary criteria HR BP SPL

Participant characteristics

Garwood et al. 75M, participants in the BLSA: see Capriotti et al. (1981) (1982) 15M (age 30 ± 39; A = 35.2); 15M (age 40 ± 49; A = 44.5); 15M (age 50 ± 59; A = 53.7); 15M (age 60 ± 69; A = 65.3); 15M (age 70 ± 79; A = 73.8)

Study

TABLE 1. Continued Measure(s) with Age Effects

HR: Y greater reactivity to Mental arithmetic; stimulus presentation than O; cold pressor; isometric Age  Stimulus interaction exercise; incongruous slide; time estimation SBP: O higher baseline level than Y; O greater reactivity to stimuli than Y. DBP: Age  Stimulus interaction 2 concurrent tasks: HR: Age  Interval interaction reaction task and SBP: O higher baseline level mental arithmetic than Y. DBP: O higher baseline level than Y HR: Y greater reactivity to Discuss events of day; discuss mutually agreed stimulus presentation than O; Y higher basal level than O; upon, pleasant topic; Age  Stimulus interaction discuss topic of continuing disagree- SCL: Y higher basal level than O ment in marriage

Stressor task(s)

614 A.W. Lau et al.

Reaction task; learning task

Shock-tone

HR BP EDA

GSR

44M, Veterans Affairs hospital Acute medical distress; medication use; score patients: 21M from surgical < 7 or >12 on the ward (age 20 ± 35; A = 27.8); WAIS vocab subtest; 23M from nursing care unit and surgical ward (age 55 ± 70; alcoholism; brain damage; nonambulaA = 63.2) tory; psychiatric disorder History of cardiac disorder and circulatory disorder; gross hearing deficit

Shmavonian 50M, 12F: 25M students et al. (1965) (age 18 ± 22; A = 20); 12F students (age 18 ± 22; A = 20); 25M (age 59 ± 76; A = 65) community-dwelling, from U.S. Employment Office

Powell et al. (1980)

2-step exercise

140M, patients and employees of Baltimore city hospitals (ages 20 ± 29; 30 ± 39; 40 ± 49; 50 ± 59; 60 ± 69; 70 ± 79; 80 ± 92).

Norris et al. (1953)

HR BP

50M, Caucasian: 24M students (age 18 ± 32; A = 22.5); 26M community-dwelling (age 66 ± 89; A = 73.7)

Reaction task

Stressor task(s)

Inability to perform the exercise

Physiological measure(s) HR

Exclusionary criteria Arrhythmic heart disorders

Participant characteristics

Morris & Thompson (1969)

Study HR: Y greater reactivity to stimulus presentation than O; O greater deceleration poststimulus presentation than Y; Age  Interval interaction HR: Age  Exercise interaction SBP: O slower recovery to prestimulus levels than Y; O more reactive to stimulus than Y; O greater response decrease than Y during postural tilt; Age  Exercise interaction DBP: O greater response decrease than Y during postural tilt HR: Y higher basal level than O. SBP: O higher baseline level than Y; O greater BP during learning task than old. DBP: O higher baseline level than Y. EDA: Y greater reactivity to stimulus presentation than O. GSR: O fewer/smaller responses during conditioning period; O smaller basal (preshock) conductance values than Y

Measure(s) with Age Effects

Psychophysiological Arousal in Older Adults 615

Participant characteristics

Exclusionary criteria

None reported

Phrases for young; phrases for old

Shock-tone

HR

GSR

Shock-tone

Stressor task(s)

GSR

Physiological measure(s)

HR: O fewer trials to extinguish than Y during adaptation and during extinction period; O fewer/ smaller responses during conditioning period GSR: O decreased mean GSR amplitude than Y

GSR: O fewer trials to extinguish than Y during adaptation and during extinction period; O fewer/ smaller responses during conditioning period; O smaller basal (preshock) conductance values than Y

Measure(s) with Age Effects

M = male; A = mean age: HR = heart rate; BP = blood pressure; MAP = mean arterial pressure; Y = younger adults; O = older adults; NIMH = National Institute of Mental Health; GSR = galvanic skin response; CVD = cardiovascular disease; BLSA = Baltimore Longitudinal Study of Aging; SCL = skin conductance level; F = female; EDA = electrodermal activity; SCR= skin conductance response; MI = myocardial infarction; AD = antidepressants; SBP = systolic blood pressure; ANS = autonomic nervous system; SPL = skin potential level; DBP = diastolic blood pressure; ESL = English as a second language; MSS = marital satisfaction scale; WAIS = Wechsler Adult Intelligence Scale.

Silverman 20M: 10M students et al. (1958) (age 20 ± 24; A = 22); 10M (age 60 ± 70; A = 65)

Hearing impairment; Shmavonian 20M, 20F: 10M students history of cardioet al. (1968) (age 18 ± 25; A = 19.6); vascular problems 10F students (age 17 ± 21; A = 18.6); 10M (age 61 ± 73; A = 66) and 10F (age 68 ± 76; A = 69.8) from Golden Age Club or U.S. Employment Office, community-dwelling Shmavonian see Shmavonian et al. (1968) see Shmavonian et al. (1970) et al. (1968)

Study

TABLE 1. Continued

616 A.W. Lau et al.

Psychophysiological Arousal in Older Adults

617

challenge, but required minimal physical activity of the participants. Tasks of this nature, including mental arithmetic, reaction time tasks, and cold pressor challenges, have been shown to evoke ``fairly sizeable [physiological] responses'' (Krantz, Manuck, & Wing, 1986, p. 87). Although a physical stressor task can produce psychological stress, it differs from a mental stressor in that it also elicits a characteristic physiological response ``even in an unconscious subject'' (Buell, Alpert, & McCrory, 1986, p. 127). More specifically, a physical stressor can be defined as a physical manipulation that can be characterized in physical dimensions and units, that is time-defined, and exhibits a dose ± response capability (see Buell et al., 1986). It is important to note that several publications reported on the same three studies. Articles by Faucheux et al. (1981), Faucheux, Baulon, et al. (1983), and Faucheux, Dupuis, et al. (1983) appear to report results from the same psychophysiological study. That is, Faucheux et al. reported the effects of a mental stressor on blood pressure, whereas Faucheux, Dupuis, et al. reported the effects of the same stressor, with the same participants, on heart rate. Apparently also based upon the same participants, Faucheux, Baulon, et al. reported the relation between self reported anxiety and various physiological measures. Similarly, Shmavonian et al. (1968, 1970) each separately reported the results of different physiological measurements from the same conditioning study. Articles by Capriotti et al. (1981) and Garwood et al. (1982) apparently resulted from the same research project, the former study reporting on a subset of data collected during the ongoing investigation of the latter study. In general, older adults exhibited lower physiological reactivity than younger adults, especially in terms of cardiovascular reactivity to stimuli. Younger adults had higher basal levels and were more reactive to stressors on electrodermal measures (e.g., skin conductance, skin potential) and heart rate measures than older adults (Barnes et al., 1982; Botwinick & Kornetsky, 1960; Ditto et al., 1987; Faucheux, Dupuis, et al., 1983; Garwood et al., 1982; Levenson et al., 1994; Morris & Thompson, 1969; Powell et al., 1980; Shmavonian et al., 1965, 1968), while older adults had higher basal levels on blood pressure measures (Boutcher & Stocker, 1996; Ditto et al., 1987; Faucheux et al., 1981; Garwood et al., 1982; Jennings et al., 1990; Powell et al., 1980). Moreover, older adults exhibited heart rate deceleration, compared to heart rate acceleration in younger adults, and slower recovery to baseline levels in heart rate relative to younger adults following stimulus presentations. The overall pattern of cardiovascular response observed among older adults is consistent with reports of diminished cardiac output and increased vascular resistance among older adults (Faucheux, Baulon, et al., 1983; Furchtgott & Busemeyer, 1979; Morris & Thompson, 1969). Although virtually all studies that looked at systolic blood pressure (SBP) and diastolic blood pressure (DBP) reported increased baseline levels among older adults, compared to younger adults, findings for significant group differences on blood pressure reactivity are equivocal. Norris et al. (1953) and Garwood et al. (1982) reported that older adults exhibited slower cardiovascular recovery to pre-stimulus levels than younger adults. In addition, when exposed to a postural tilt stressor, older adults exhibited a greater decrease in SBP and DBP, another indication of decreased vascular resistance with age (Norris et al., 1953). However, except for two reported Age  Stimulus interactions (Ditto et al., 1987; Garwood et al., 1982), no group differences in reactivity to stimuli were found for DBP or mean arterial pressure. And despite predictions of increased SBP reactivity among older adults, only four studies found significantly greater SBP responding in older adults to a mental or physical

618

A.W. Lau et al.

stressor than younger adults (Faucheux et al., 1981; Garwood et al., 1982; Norris et al., 1953; Powell et al., 1980). Older adults also were found to be less responsive than younger adults on measures of galvanic skin response and heart rate response during conditioning trials (Botwinick & Kornetsky, 1960; Shmavonian et al., 1965, 1968, 1970). Moreover, older adults, compared to younger adults, required fewer trials to extinguish physiological responding during adaptation, and more quickly returned to pre-shock levels as compared to younger adults during extinction (Botwinick & Kornetsky, 1960; Shmavonian et al., 1968, 1970). However, findings for dampened electrodermal activity responses in older adults to physical stressors are tenuous at best. Only one out of the three studies that measured skin conductance response to a physical stressor found significant differences between age groups, reporting an Age  Gender interaction, with greater skin conductance responses in younger than older females (Eisdorfer et al., 1980). METHODOLOGICAL CRITIQUE Participant Selection Almost all the studies evidenced problems with participant selection and recruitment, limiting generalizability and introducing possible confounds to research findings. Although several psychiatric and medical conditions could have influenced outcome of these studies, 13 studies did not assess for pre-existing psychiatric conditions or level of anxiety among participants (Barnes et al., 1982; Botwinick & Kornetsky, 1960; Boutcher & Stocker, 1996; Capriotti et al., 1981; Ditto et al., 1987; Furchtgott & Busemeyer, 1979; Garwood et al., 1982; Jennings et al., 1990; Levenson et al., 1994; Morris & Thompson, 1969; Shmavonian et al., 1965, 1968, 1970); 9 studies did not screen for medication or substance use (Botwinick & Kornetsky, 1960; Ditto et al., 1987; Jennings et al., 1990, Levenson et al., 1994; Morris & Thompson, 1969; Powell et al., 1980; Shmavonian et al., 1965, 1968, 1970); 5 studies included individuals with medical conditions (Botwinick & Kornetsky, 1960; Levenson et al., 1994; Norris et al., 1953; Powell et al., 1980; Silverman et al., 1958); and only 1 study (Faucheux et al., 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983) reported assessing for visual and hearing impairments. One study did not report any exclusionary criteria (Eisdorfer et al., 1980). In addition, with the exception of six studies, three of which neglected to report from where they recruited their participants (Boutcher & Stocker, 1996; Eisdorfer et al., 1980; Silverman et al., 1958), all studies employed active, community-dwelling, psychologically minded individuals. Four studies recruited older adults from existing subject pools (Capriotti et al., 1981; Ditto et al., 1987; Furchtgott & Busemeyer, 1979; Garwood et al., 1982). Across these studies, experience with psychological experiments may have influenced the magnitude of cardiovascular responses to experimental stimuli. Moreover, participants from Capriotti et al. (1981) and Garwood et al. (1982) were anecdotally health-conscious and psychologically minded individuals, and reportedly volunteered to participate in the research pool in exchange for the benefit of free regular physical examinations (Stone & Norris, 1966). The participant selection process of Botwinick and Kornetsky (1960) and Norris et al. (1953) also may have limited the generalizability of each study's respective results. While Norris et al. recruited participants from hospital patients and employees, recruiting anyone who could ``perform the exercise,'' Botwinick and Kornetsky

Psychophysiological Arousal in Older Adults

619

recruited their older participants from a National Institute of Mental Health research pool and their younger participants were ``religious volunteer subjects'' that, at the time of the study, were residing in a ward of the Clinical Center of the National Institute of Health. Controlling Health Behaviors A second methodological problem that was pervasive across the psychophysiological studies is the inadequate control of health behaviors that can affect autonomic nervous system arousal prior to the experimental session. By not assessing health behaviors and not restricting relevant behaviors prior to the experimental session, significant experimental confounds may have occurred. Only four studies restricted caffeine, alcohol, or nicotine use prior to the experimental session (Barnes et al., 1982; Boutcher & Stocker, 1996; Faucheux et al., 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983; Shmavonian et al., 1965); only two studies assessed for height and weight differences between groups (Boutcher & Stocker, 1996; Jennings et al., 1990); and only one study controlled for the use of diuretics (Garwood, Engel, & Kusterer, 1981, Garwood et al., 1982). Exercise behaviors also are important to monitor and control when measuring skin conductance responses in older adults. Garwood et al. (1981) reported high positive correlations between outdoor activity and skin potential levels as well as basal skin potential levels in older adults. Only the studies by Shmavonian et al. (1965) and by Faucheux and colleagues screened for physical activity prior to the experimental session. Task Effectiveness A third methodological problem involves the integrity of the stressor tasks employed by the various studies to elicit responding. It is possible that the lackluster evidence to support significant reactivity differences between age groups may be due to the nature of the stressor tasks employed. Although lack of reactivity to a stimulus may result from the stimulus not being adequately engaging or challenging, it may also result if the task is too difficult or frustrating, resulting in disengagement or a fatigue effect. Self-report measures of task difficulty or perceived engagement and measures of task performance are ways to assess whether participants were challenged by, or were disengaged from, the stressor task. Six studies employed a manipulation check of this type to assess the stress- or anxiety-provoking nature of the task (Barnes et al., 1982; Boutcher & Stocker, 1996; Faucheux, Baulon, et al., 1983; Jennings et al., 1990; Shmavonian et al., 1968, 1970). However, neither Jennings et al. (1990) nor Shmavonian et al. (1968, 1970) reported the results of their stress /anxiety measures, and none of the remaining three studies reported significant differences in self-reported anxiety between older and younger participants during the stressor condition (Barnes et al., 1982; Boutcher & Stocker, 1996; Faucheux, Baulon, et al., 1983). Tellingly, on average, the participants in the latter three studies rated their respective tasks as less than moderately difficult or anxiety-provoking, and no significant differences between pre- and post-task subjective units of distress ratings were found. These results suggest that the tasks employed in these studies may not have been sufficiently challenging. There is also some concern as to the questionable psychometric properties of the self-report instruments employed to assess the stressfulness of the task (Kogan et al.,

620

A.W. Lau et al.

2000). Barnes et al. (1982) and Boutcher and Stocker (1996) administered the State Trait Anxiety Inventory (STAI; Spielberger, Gorsuch, & Lushene, 1970); Jennings et al. (1990) administered the Stress-Arousal Checklist (SACL; Mackay, 1980); and Faucheux and colleagues (Faucheux et al., 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983) used the Masked Anxiety and Manifest Anxiety Questionnaire (Cattell, 1962) and the anxiety and internalization scales of the small Minnesota Multiphasic Personality Inventory (MMPI; Perse & LeBeaux, 1977). The psychometric properties of these instruments when used with older adults remain in question (Barnes et al., 1982; Boutcher & Stocker, 1996; Faucheux, Baulon, et al., 1983). Little evidence exists for the content validity of the STAI with older adults (Kogan et al., 2000) and the validity of the MMPI used with older adults may also be questioned, as age does affect MMPI profiles (for review, see Green, 1991). It should be noted, however, that in general, there are few self-report measures of anxiety that are normed with older adults. Another way to measure task effectiveness is to measure task performance. Only five studies reported information regarding task performance (Barnes et al., 1982; Boutcher & Stocker, 1996; Furchtgott & Busemeyer, 1979; Jennings et al., 1990; Powell et al., 1980). Consistent with use of manipulation checks, three studies reported differential performance between younger and older participants as well as a negative correlation between physiological reactivity and performance (Furchtgott & Busemeyer, 1979; Jennings et al., 1990; Powell et al., 1980). The fact that performance was negatively correlated with age suggests that any differences in physiological reactivity observed between the two age groups could be attributable to the differential performance on the task rather than any age-related change in physiological reactivity. Moreover, lack of age group differences in task performance found in Barnes et al. (1982), Boutcher and Stocker (1996), and on the mental arithmetic component of the Furchtgott and Busemeyer (1979) study support the theory that the tasks employed were not challenging enough to elicit responding, as participants in the studies performed equally well on their respective tasks. Studies that utilized a physical stressor also did not employ a manipulation check on the perceived rigor and physical stress by the individual during the physical stressor task(s). Although physical stressors are defined by their ability to elicit a physiological response, they also exhibit a characteristic dose ±response capabilityÐthe more intense the stressor, the greater the subsequent response (Buell et al., 1986). Although a physical stressor task may have elicited physiological responding among all participants, differential responding between age groups may not have emerged due to differential task performance, ability, and appraisal. It is possible, for example, that older adults performed these physical tasks more slowly or with less exertion than younger adults. Furthermore, each of the four studies employed a different physical stressor task. Thus, it is difficult to compare findings across studies due to the unique physiological demands each task examined elicited. Another methodological concern is the lack of attention to the ecological validity of the tasks chosen. Although laboratory stressor tasks have been shown to evoke physiological arousal in participants, they still represent a re-creation of actual environmental stressors that evoke the perception of threat or fear among individuals. Although three studies used participant-specific, emotionally laden stimuli, it is questionable whether these stimuli represent equivalent stressors across participants (Ditto et al., 1987; Levenson et al., 1994; Silverman et al., 1958). Silverman et al.

Psychophysiological Arousal in Older Adults

621

(1958) reported using phrases that were ``emotionally charged'' specifically for young adults, and phrases that were ``emotionally charged'' for older adults. However, the authors did not report the content of these phrases, nor did they discuss how the particular phrases were selected and how they determined that they were ``emotionally charged.'' Ditto et al. (1987) directed their subjects to imagine an anxietyprovoking situation, one that they had experienced. However, no manipulation checks were employed to determine whether participants were sufficiently engaged in the task (e.g., verification of the situation or on what to focus), and there was no assessment for avoidance strategies that may have been used during the imaginal exercise (e.g., disengagement, distraction). Levenson et al. (1994) asked couples to discuss a variety of topics, including a topic of continuing disagreement in their marriage. It is unclear whether this task evoked anxiety, stress, anger, disgust, or embarrassment, because no manipulation check was conducted. Although the authors found an Age  Conversation interaction, they could not conduct further analyses because order of conversation topics was not counterbalanced. This is unfortunate because identification of conversation topics that resulted in age differences in physiological responsivity may have helped identify specific stimulus characteristics in which age differences in physiological responding might be observed. Levensen, Carstensen, Friesen, and Ekman (1991) have reported that different emotions produced different patterns of physiological responses. Although participants were asked to identify anxiety-evoking stimuli, it is impossible to determine whether the stimuli selected by each participant actually evoked the desired response. Problems Related to Repeated Measures Design Another methodological shortcoming of these investigations is the general disregard of procedures that have been shown to influence measures of physiological reactivity in repeated measures designs. For example, several studies did not control for potential order effects when multiple stressors were used. As such, order effects may explain differences in physiological reactivity to a particular stimulus (Barnes et al., 1982; Ditto et al., 1987; Faucheux, Dupuis, et al., 1983; Furchtgott & Busemeyer, 1979). And as was previously mentioned, Levenson et al. (1994) failed to control for order effects across conversation types, and therefore were unable to describe adequately their significant Age  Conversation interaction. Another concern is the use of inadequate baseline periods or inter-trial intervals. Without adequate baseline periods or inter-trial intervals, it is difficult to ascertain a participant's resting state, and thus, calculate valid change scores. Several studies allocated only 5 ±6 min for the baseline condition (Ditto et al., 1987; Levenson et al., 1994; Powell et al., 1980), which falls short of the recommended intervals for establishing an adequate baseline period (Shapiro et al., 1996). Faucheux et al. (1981) did not take a baseline measurement on the day of the experimental session. Rather, the authors substituted blood pressure readings from a physical exam conducted an unspecified number of days/weeks prior to the experimental session for the traditional baseline readings. Several studies that used multiple mental stressors also did not allocate enough time (e.g., none to 5 min) between stimulus presentations (Ditto et al., 1987; Faucheux, Dupuis, et al., 1983; Furchtgott & Busemeyer, 1979; Levenson et al., 1994; Morris & Thompson, 1969; Powell et al., 1980; Silverman et al., 1958). As a

622

A.W. Lau et al.

result, measures of physiological reactivity to each successive stimulus may have been influenced by pre-stimulus values that reflect both basal functioning and recovery from the preceding task. Measures of reactivity to multiple stimuli may also be influenced by differential effects of fatigue resulting from a continuous succession of demands, or from disengagement due to the frustration of multiple demands. Problems With Data Analysis Another inconsistency among these studies related to those mentioned regarding length of baseline, is the method used to calculate reactivity. Some studies calculated change scores (e.g., Levenson et al., 1994; Morris & Thompson, 1969; Powell et al., 1980), whereas others used absolute levels of physiological parameters in the analysis (e.g., Eisdorfer et al., 1980; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983). Furthermore, some researchers employed analyses of covariance to eliminate the effects of baseline differences (e.g., Furchtgott & Busemeyer, 1979; Garwood et al., 1982), while others transformed raw scores into standard scores (z-scores) to eliminate variability across physiological measurements (e.g., Ditto et al., 1987; Garwood et al., 1982). Rather than conduct covariance analyses for baseline values, or examine differences between post-stimulus responding and baseline levels, for example, Morris and Thompson (1969) and Powell et al. (1980) defined reactivity as the difference between pre-stimulus (e.g., period between warning signal and stimulus; immediately prior to stimulus presentation) and post-stimulus measurements per trial. Since baseline differences were apparent for at least blood pressure and electrodermal activity, some attention to controlling for these differences via analysis of covariance or residualized change score analyses for examining reactivity is clearly warranted. Several studies possessed inadequate power to detect age differences due to small sample sizes. Some studies included groups with only 10 participants per group (e.g., Barnes et al., 1982; Silverman et al., 1958) and found no significant results with some variables. Barnes et al. (1982) reported the findings of a ``control study'' that only employed 4 out of their 20 participants. The authors randomly selected four older adult participants to also undergo the protocol without the mental stressor tasks, and used the within-subject results to show the effectiveness of their protocol to evoke responses from participants. In addition, a shortcoming of several other studies is the failure to conduct and/or report findings that may have provided more information regarding the observed age differences in reactivity (Capriotti et al., 1981; Faucheux, Baulon, et al., 1983; Garwood et al., 1982; Levenson et al., 1994). Garwood et al. (1982) did not conduct follow-up tests for main effects and interaction effects, but instead conducted correlational analyses. Although general trends were noted from their correlation matrix, more specific information regarding differences between age differences across decades was lost. Capriotti et al. (1981) and Faucheux, Baulon, et al. (1983) did not find significant reactivity differences. However, both studies collapsed reactivity values across the multiple stimuli used in their respective studies instead of conducting separate analyses for each task. Because of the number and diversity of stressor tasks employed in these studies, any significant age differences in reactivity for a particular stressor type would be impossible to determine. Although Norris et al. (1953) reported a large number of participants and an equally large number of age groups, the authors failed to report how many

Psychophysiological Arousal in Older Adults

623

participants were included in each age group. In addition, the authors did not report follow-up tests for main or interaction effects, nor did they provide the results of statistical analyses or descriptive statistics to support their descriptive reports of the data. Therefore, it is impossible to know to which age group(s) the authors are referring when they report differences between ``older subjects'' and ``younger subjects.'' Results were also difficult to interpret for Ditto et al. (1987) because different task protocols were used for younger and older adults. Older adults were given easier mental arithmetic problems and were run through the experimental protocol in their homes, while younger adults were given more difficult math problems and underwent the experiment in a laboratory setting. Thus, results from group analyses are difficult to interpret because the groups were not administered the same stressor task and were exposed to very different experimental conditions. Moreover, the recording apparatus used to measure physiological responding differed between groups. Age Classification A final methodological problem observed in several studies is the heterogeneous nature of the designated age groups. Although the classification of ``older adult'' and ``younger adult'' encompasses a great range of ages, meaningful stratifications exist within each designated age group. Just as the younger adult classification typically includes middle-aged individuals, the older adult classification typically includes young-old adults (65 ± 74 years), old-old adults (75 ±84 years) and oldest-old adults (>85 years; Fisher, Zeiss, & Carstensen, 1993). For example, Ditto et al. (1987) compared individuals who were 17 ±28 years of age with older individuals who were 60 ± 96 years in age. Not only is the discrepancy between age groups vast, but participants within the older adult group included young-old as well as oldest-old adults. In some other studies, the discrepancy between the age groups is minimal because the individuals in the younger adult group were actually middle-aged adults, and the older adults were young-old adults (Faucheux et al., 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983; Levenson et al., 1994). Boutcher and Stocker (1996) failed to report the age ranges for their groups, and therefore it is unclear whether their older adult group consisted of young-old adults, or a mix of middle-aged adults and young-old adults. It is possible that extreme ranges of ages used or relatively constricted age ranges used influenced the extent to which significant age differences in physiological reactivity were observed.

CONCLUSIONS The question of whether older adults differ in physiological responding to anxietyrelated stressors as compared to younger adults still has yet to be adequately answered. First, there is a paucity of literature on the psychophysiological assessment of older adults, particularly among older adults with anxiety disorders. Second, the existing literature contains studies with significant methodological problems that complicate the drawing of any firm conclusions regarding the physiological responsivity of older adults. Thus, the conclusions one can draw from the preceding review are quite limited by both the paucity of relevant literature and the methodological limitations of the published studies. Of the 20 published articles that met inclusion

624

A.W. Lau et al.

criteria for this review, 11 articles had such a large combination of methodological problems that their findings on the differences in psychophysiological responses between older and younger adults are virtually uninterpretable (Barnes et al., 1982; Botwinick & Kornetsky, 1960; Ditto et al., 1987; Eisdorfer et al., 1980; Faucheux et al., 1981; Furchtgott & Busemeyer, 1979; Levenson et al., 1994; Morris & Thompson, 1969; Norris et al., 1953; Powell et al., 1980; Silverman et al., 1958). These studies had multiple methodological problems including recruitment practices that limited generalizability: failure to assess for, or failure to exclude participants based on medical/psychiatric conditions or medication use that could introduce possible confounds to research findings; failure to assess for, or eliminate participants with health behaviors that could influence autonomic nervous system baseline values and reactivity levels; failure to provide evidence, or suitable arguments, that the stimuli were adequately stressful or sufficiently challenging to elicit physiological reactivity; and failure to employ adequate baseline periods and/or inter-trial intervals, thus jeopardizing the validity of change scores and measures of reactivity to multiple stimuli. The remaining nine articles also had methodological shortcomings, however, they also contained enough methodologically sound elements to support a cautious discussion of their reported results (Boutcher & Stocker, 1996; Capriotti et al., 1981; Faucheux, Baulon, et al., 1983; Faucheux, Dupuis, et al., 1983; Garwood et al., 1982; Jennings et al., 1990; Shmavonian et al., 1965, 1968, 1970). Thus, although the studies reviewed in this paper are fraught with significant methodological shortcomings, they offer a limited understanding of age differences in physiological reactivity to stressful challenges. Based upon findings from the methodologically stronger studies, cardiovascular reactivity to stressors appears to be somewhat attenuated in older adults when compared to younger adults (Boutcher & Stocker, 1996; Faucheux, Dupuis, et al., 1983; Garwood et al., 1982; Jennings et al., 1990; Shmavonian et al., 1970). Although there is equivocal evidence for age-related differences in resting heart rate (Boutcher & Stocker, 1996; Ditto et al., 1987; Furchtgott & Busemeyer, 1979; Jennings et al., 1990; Morris & Thompson, 1969; Powell et al., 1980; Shmavonian et al., 1970), there is ample evidence for greater heart rate reactivity to stressor tasks in younger adults than older adults (Boutcher & Stocker, 1996; Garwood et al., 1982; Faucheux, Dupuis, et al., 1983; Jennings et al., 1990; Shmavonian et al., 1970). In addition, two studies reported that older adults exhibited quicker recovery to baseline and faster extinction to a stimulus than younger adults (Faucheux, Dupuis, et al., 1983; Shmavonian et al., 1970). However, this latter finding is likely due to the lower heart rate response magnitude of the older adults to a stressor. Unlike data on resting heart rate, higher resting blood pressure appears to be reliably observed in older adults compared to younger adults (Boutcher & Stocker, 1996; Garwood et al., 1982; Jennings et al., 1990). However, it is unclear whether young and older adults differ in blood pressure reactivity and rate of recovery due to the questionable adequacy of stressor tasks and the inadequate screening of participants in studies that have examined age-related differences in blood pressure. Finally, findings regarding electrodermal activity are equivocal. One group of researchers (Shmavonian and colleagues) reported smaller baseline values and smaller response and potential levels from older adults as compared to younger adults during conditioning, and faster extinction to a stimulus than younger adults. In contrast, another group of researchers (Garwood and colleagues) did not find significant age effects for skin potential or conductance levels. Additional data will be

Psychophysiological Arousal in Older Adults

625

needed to examine age-related differences in electrodermal activity levels and responsivity to test stimuli. Clinical Implications Findings of studies reviewed herein have implications for both the assessment and treatment of anxiety-related problems in older adults. One of the implications for psychophysiological assessment of anxiety is that individuals conducting clinical trials and treatment studies using older adults need to be more selective regarding their choice of psychophysiological measures. For example, although the results are equivocal, there is a reasonable possibility that older adults will yield minimal changes in, or smaller levels of, electrodermal activity than that seen in younger adults at baseline and in response to anxiety-evoking stimuli. Thus, electrodermal activity or skin temperature change may not be the best choice of dependent variables. Because older adults may react less than younger adults on measures of electrodermal activity, it is possible that physiological measurement of electrodermal activity with older adults may be less useful in identifying phobic stimuli to target during treatment or in monitoring change during intervention. In this case, direct observation or self-report measures of anxiousness may turn out to be more useful for assessing anxiety in older adults. One must also be cautious in interpreting physiological responses of older adults, and not necessarily expect to see response patterns similar to those of younger adults. These findings also have implications regarding the self-report assessment of autonomic arousal often included in clinical interviews with anxiety disorder patients. Older adults may experience physical symptoms with less intensity than expected for a younger individual with an anxiety disorder. Older adults may not endorse physiological symptoms of fear or anxiety because they do not experience them as described to them during an interview or in a self-report instrument. It is also possible that older adults are not endorsing anxiety symptoms because they are attributing the same symptoms to a medical problem. Approximately 86% of older adults have one or more chronic medical conditions, and more than 50% of older adults have two or more medical conditions (U.S. Senate Special Committee on Aging, American Association of Retired Persons, Federal Council on the Aging, and U.S. Administration on Aging, 1991). The medications taken for these and other illnesses, and some of the illnesses themselves, can produce anxiety-like symptoms, both in terms of their experience and their behavioral features. For example, individuals with diabetes or hyperthyroidism may experience somatic symptoms similar to those experienced during a panic attack, such as racing heart, cold sweat, and trembling. Thus, their chief complaint would be physical and they would be more likely present to a medical care provider than a psychologist. In addition, individuals over age 65 grew up in an era in which mental disorders were considered socially undesirable, and therefore they may find it acceptable to attribute their physical symptoms to medical reasons and explain their experience through somatic terms. Because older adults, in contrast to younger adults, are likely to be familiar with medical terms and procedures, and less familiar with psychological terminology, older adults may present with more somatic complaints because they have no other language to describe their experiences. Although the actual experience of physiological symptoms of anxiety may be less intense among older adults, they may report more physiological symptoms than younger adults. Thus, when assessing for anxious

626

A.W. Lau et al.

symptoms, clinicians should exercise caution when interpreting the self-reported arousal of older adult clients. There are several implications of the reviewed studies for the treatment of anxiety disorders in older adults. If older adults exhibit more rapid physiological extinction to a feared stimulus than younger adults, as suggested by the reviewed studies, one might speculate that exposure therapy might operate more efficiently among older adults than younger adults because of their developmental physiological disposition. Further, if older adults exhibit a lesser physiological response to a stimulus and its associated faster habituation rate, it is also possible that their physiological symptoms are not as intense and that treatment may work more expediently for older than younger adults. All of these conclusions, however, should be considered speculative, due to the complete lack of data on physiological responsiveness among older adults with anxiety disorders. It is unclear whether anxiety-disordered older adults will respond similarly to older adults not selected on the basis of anxiousness, or whether they will show more physiological responsiveness like their younger adult anxiety disorder counterparts. Until these data are available, we cannot make any clinical recommendations for the use of physiological measures in the assessment of older adult patients with anxiety disorders. Future Research Directions The paucity of research examining autonomic arousal among older adults, coupled with the methodological shortcomings of existing studies, invites a multitude of unanswered questions. Much of the research with younger adults requires replication with older adults in which age-related comparisons are made, as the literature we have reviewed suggests some fundamental differences in responsivity among various age groups. Beyond this categorical recommendation, we believe a few specific topics deserve attention from researchers. Levenson et al. (1991) has made some very important findings regarding the differential responsiveness of adults to stimuli designed to elicit different emotions. The results of this study open a second assessment window to complement selfreported emotional arousal. As studies have found that anxious younger adults respond differently to anxiety-evoking stimuli than nonanxious individuals (Ehlers, Margraf, Roth, Taylor, & Birbaumer, 1988; Lader & Wing, 1964; Rapee, 1985), a next logical step is to employ Levenson's methodology to determine whether age-related differences exist in the psychophysiological expression of anxious and nonanxious older adults. The findings from such an investigation would have important implications for the clinical assessment of anxiety and our understanding of the experience of anxiety among older adults. The finding that older adults exhibit a pattern of weak conditioning of physiological responding and rapid extinction to a stimulus warrants further investigation. These findings suggest that older adults may have a diminished capacity to acquire and maintain a phobic fear (Barlow, 1988; Forsyth & Eifert, 1996), which in turn has theoretical implications regarding the acquisition and maintenance of anxiety symptoms in older adults. The construct of fear and/or anxiety may differ for older adults than younger adults, as they may experience it as less intense and less enduring. There exists a body of literature that suggests older adults are not at greater risk for negative psychological effects, or may even be less vulnerable to the

Psychophysiological Arousal in Older Adults

627

psychological consequences of traumatic or stressful events than younger adults because they have been found to report less intense or fewer negative trauma symptoms on trauma-related assessment measures than younger adults following natural disasters (Falk, Hersen, & Van Hasselt, 1994; Fields, 1996; Green, Gleser, Lindy, Grace, & Leonard, 1996). In light of the theoretical implications of the conditioning studies, it is possible that older adults may not possess an age-related psychological buffer (e.g., resiliency or better coping strategies) but rather a physiological buffer that modifies the experience, interpretation, and subsequent psychosocial consequences of a stressful event or fearful situation. Conditioning studies used in this literature unfortunately have neither used a fearful object, nor employed anxious older adults (Shmavonian et al., 1965, 1968, 1970). Further investigation of fear conditioning in older adults is clearly warranted. Finally, the existing literature does not address the question of whether differential physiological responding exists among the subgroups within the very broad older adult category. As our physiology ages continuously, it would not be incorrect to hypothesize that these age-related differences in physiological arousal and responding attenuate more with each decade of life. For example, old-old adults may respond differently than young-old adults, or young-old adults may respond similarly to old-young adults. Sole use of cross-sectional studies will not completely address this question, mainly because of the potential cohort effects and selective rates of death and illness. If, for example, anxiety were associated with increased mortality as some authors have suggested (Kawachi, Sparrow, Vokonas, & Weiss, 1994), those that survive into the older-old group might actually be less anxious than their young-old counterparts. Despite a paucity of relevant literature and methodological limitations of the published studies, there does exist a small foundation from which to draw tentative conclusions on the psychophysiological responses of older adults, and upon which to build future investigations on the somatic ± physiological responses associated with anxiety in older adults. Although it is unsettling that a rapidly growing segment of the population in the United States (e.g., older adults) may not have adequate assessment or treatment methods for the most prevalent mental disorder problem in the country (Flint, 1994), it is exciting that a whole area in psychology has yet to be explored.

REFERENCES Abel, G. G., Blanchard, E. B., Barlow, D. H., & Mavissakalian, M. (1975). Identifying specific erotic cues in sexual deviations by audiotaped descriptions. Journal of Applied Behavior Analysis, 8, 247 ± 260. Anderson, N. B., & McNeilly, M. (1991). Age, gender, and ethnicity as variables in psychophysiological assessment: sociodemographics in context. Psychological Assessment, 3, 376 ± 384. Barlow, D. H. (1988). Anxiety and its disorders. New York: Guilford Press. Barnes, R. F., Raskind, M., Gumbrecht, G., & Halter, J. B. (1982). The effects of age on the plasma catecholamine response to mental stress in man. Journal of Clinical Endocrinology and Metabolism, 54, 64 ± 69. Bland, R. C., Orn, H., & Newman, S. C. (1988). Prevalence of psychiatric disorders in the elderly in Edmonton. Acta Psychiatrica Scandinavia, 77, 57 ± 63. Blazer, D., George, L. K., & Hughes, D. (1991). The epidemiology of anxiety disorders: an age comparison. In: C. Salzman, & D. Lebowitz (Eds.), Anxiety in the elderly: treatment and research ( pp. 17 ± 30). New York: Springer. Botwinick, J., & Kornetsky, C. (1960). Age differences in the acquisition and extinction of the GSR. Journal of Gerontology, 15, 83 ± 84.

628

A.W. Lau et al.

Boutcher, S. H., & Stocker, D. (1996). Cardiovascular response of young and older males to mental challenge. Journal of Gerontology, 51, P261 ± P267. Buell, J. C., Alpert, B. S., & McCrory, W.W (1986). Physical stressors as elicitors of cardiovascular reactivity. In: K. A. Matthews, S. M. Weiss, T. Detre, T. M. Dembroski, B. Falkner, S. B. Manuck, R. B. Williams Jr. (Eds.), Handbook of stress reactivity, and cardiovascular disease (pp. 127 ± 144). New York: Wiley. Capriotti, R., Garwood, M., & Engel, B. T. (1981). Skin potential level: age and recording site interactions. Journal of Gerontology, 36, 40 ± 43. Catania, J. J., Thompson, L. W., Miachalewski, H. A., & Bowman, T. E. (1980). Comparisons of sweat gland counts, electrodermal activity, and habituation behavior in young and old groups of subjects. Psychophysiology, 17, 146 ± 152. Cattell, R. B. (1962). Manuel de l'echelle d'anxiete de Cattell. Paris: Centre de Psychologie Appliquee. Cone, J. D. (1979). Confounded comparisons in triple response mode assessment research. Behavioral Assessment, 1, 85 ± 95. Ditto, B., Miller, S., & Maurice, S. (1987). Age differences in the consistency of cardiovascular response patterns in healthy women. Biological Psychology, 25, 23 ± 31. Ehlers, A., Margraf, J., Roth, W. T., Taylor, C. B., & Birbaumer, N. (1988). Anxiety induced by false heart rate feedback in patients with panic disorder. Behaviour Research and Therapy, 26, 1 ± 11. Eisdorfer, C., Doerr, H. O., & Follette, W. (1980). Electrodermal reactivity: an analysis by age and sex. Journal of Human Stress, 6, 39 ± 42. Falk, B., Hersen, M., & Van Hasselt, V. B. (1994). Assessment of post-traumatic stress disorder in older adults: a critical review. Clinical Psychology Review, 14, 383 ± 415. Faucheux, B. A., Bourleire, F., Baulon, A., & Dupuis, C. (1981). The effects of psychosocial stress on urinary excretion of adrenaline and noradrenaline in 51- to 55- and 71- and 74-year-old men. Gerontology, 27, 313 ± 325. Faucheux, B. A., Baulon, A., Poitrenaud, J., Lille, F., Moreaux, C., Dupuis, C., & Bourliere, F. (1983). Heart rate, urinary catecholamines, and anxiety responses during mental stress in men in their fifties and seventies. Age and Ageing, 12, 144 ± 150. Faucheux, B. A., Dupuis, C., Baulon, A., Lille, F., & Bourliere, F. (1983). Heart rate reactivity during minor mental stress in men in their 50s and 70s. Gerontology, 29, 149 ± 160. Fisher, J. E., Zeiss, A. M., & Carstensen, L. L. (1993). Psychopathology in the aged. In: P. B. Sutker, & H. E. Adams (Eds.), Comprehensive handbook of psychopathology (2nd ed., pp. 815 ± 842). New York: Plenum. Fields, R. B. (1996). Severe stress and the elderly: are older adults at increased risk for posttraumatic stress disorder? In: P. E. Ruskin, & J. A. Talbott (Eds.), Aging and posttraumatic stress disorder ( pp. 79 ± 100). Washington, DC: American Psychiatric Press. Flint, A. J. (1994). Epidemiology and comorbidity of anxiety disorders in the elderly. American Journal of Psychiatry, 151, 640 ± 649. Forsyth, J. P., & Eifert, G. H. (1996). Systemic alarms in fear conditioning: I. A reappraisal of what is being conditioned. Behavior Therapy, 27, 441 ± 462. Fredrikson, M. (1991). Physiological responses to stressors: Implications for clinical assessment. Psychological Assessment, 3, 350 ± 355. Furchtgott, E., & Busemeyer, J. K. (1979). Heart rate and skin conductance during cognitive processes as a function of age. Journal of Gerontology, 34, 183 ± 190. Garwood, M., Engel, B. T., & Kusterer, J. P. (1981). Skin potential level: age and epidermal hydration effects. Journal of Gerontology, 36, 7 ± 13. Garwood, M., Engel, B. T., & Capriotti, R. (1982). Autonomic nervous system function and aging: response specificity. Psychophysiology, 19, 378 ± 385. Gatz, M., Kasl-Godley, J. E., & Karel, M. J. (1996). Aging and mental disorders. In: J. E. Birren, K. W. Schaie, R. P. Abeles, M. Gatz, & T. A. Salthouse (Eds.), Handbook of the psychology of aging (4th ed., pp. 365 ± 382). San Diego, CA: Academic Press. Green, R. L. (1991). The MMPI-2/MMPI: an interpretive manual. Boston: Allyn and Bacon. Green, B. L., Gleser, G. C., Lindy, J. D., Grace, M. C., & Leonard, A. (1996). Age-related reactions to the Buffalo Creek dam collapse: fffects in the second decade. In: P. E. Ruskin, & J. A. Talbott (Eds.), Aging and posttraumatic stress disorder ( pp. 101 ± 126). Washington, DC: American Psychiatric Press. Jennings, J. R., Brock, K., & Nebes, R. (1990). Age and specific processing capacities: a cardiovascular analysis. Journal of Psychophysiology, 4, 51 ± 64. Kawachi, I., Sparrow, D., Vokonas, D., & Weiss, S. T. (1994). Symptoms of anxiety and risk of coronary heart disease: the Normative Aging Study. Circulation, 90, 2225 ± 2229.

Psychophysiological Arousal in Older Adults

629

Kogan, J., Edelstein, B., & McKee, D. (2000). Assessment of anxiety in older adults: current status. Journal of Anxiety Disorders, 14, 109 ± 132. Krantz, D. S., Manuck, S. B., & Wing, R. R. (1986). Psychological stressors and task variables as elicitors of reactivity. In: K. A. Matthews, S. M. Weiss, T. Detre, T. M. Dembroski, B. Falkner, S. B. Manuck, R. B. Williams Jr. (Eds.), Handbook of stress, reactivity, and cardiovascular disease (pp. 85 ± 107). New York: Wiley. Lader, M. H. (1967). Palmar skin conductance measures in anxiety and phobic states. Journal of Psychosomatic Research, 11, 271 ± 281. Lader, M. H., & Marks, I. (1971). Clinical anxiety. New York: Grune & Stratton. Lader, M. H., & Wing, L. (1964). Habituation of the psycho-galvanic reflex in patients with anxiety states and in normal subjects. Journal of Neurology, Neurosurgery, and Psychiatry, 27, 210 ± 218. Lakatta, E. G. (1990). Heart and circulation. In: E. L. Schneider, & J. W. Rowe (Eds.), Handbook of the biology of aging (3rd ed., pp. 181 ± 216). San Diego: Academic Press. Lang, P. J. (1968). Fear reduction and fear behavior: problems in treating a construct. In: J. M. Shilieu (Ed.), Research in psychotherapy, vol. 3 (pp. 90 ± 102). Washington: American Psychological Association. Levenson, R. W., Carstensen, L. L., Friesen, W. V., & Ekman, P. (1991). Emotion, physiology, and expression in old age. Psychology and Aging, 6, 28 ± 35. Levenson, R. W., Carstensen, L. L., & Gottman, J. M. (1994). The influence of age and gender on affect, physiology, and their interrelations: a study of long-term marriages. Journal of Personality and Social Psychology, 67, 56 ± 68. Mackay, C. J. (1980). The measurement of mood and psychophysiological activity using self-report techniques. In: I. Martin, & P. H. Venables (Eds.), Techniques in psychophysiology ( pp. 501 ± 564). Chichester: Wiley. Magni, G., & De Leo, D. (1984). Anxiety and depression in geriatric and adult medical inpatients: a comparison. Psychological Reports, 55, 607 ± 612. Magni, G., Schifano, F., deDominicis, M. G., & Belloni, G. (1988). Psychological distress in geriatric and adult medical in-patients. Archives of Gerontology and Geriatrics, 7, 151 ± 161. Montagna, W. (1965). Morphology of the aging skin: the cutaneous appendages. In: W. Montagna (Ed.), Advances in biology of skin aging ( pp. 1 ± 16). New York: Pergamon. Morris, J. D., & Thompson, L. W. (1969). Heart rate changes in a reaction time experiment with young and aged subjects. Journal of Gerontology, 24, 269 ± 277. Mower, O. H. (1939). A stimulus ± response analysis of anxiety and its role as a reinforcing agent. Psychological Review, 46, 553 ± 565. Norris, A. H., Shock, N. W., & Yiengst, M. J. (1953). Age changes in heart rate and blood pressure responses to tilting and standardized exercise. Circulation, 8, 521 ± 526. Papillo, J. F., Murphy, P. M., & Gorman, J. M. (1988). Psychophysiology. In: C. G. Last, M. Hersen, A. P. Goldstein, & L. Krasner (Eds.), Handbook of anxiety disorders. Pergamon general psychology series, vol. 151 (pp. 217 ± 250). New York: Pergamon. Perse, J., & LeBeaux, M. O. (1977). Manuel du mini-mult. Paris: Centre de Psychologie Appliquee. Porges, S. W., & Fox, N. A. (1986). Developmental psychophysiology. In: M. G. H. Coles, E. Donchin, & S. W. Porges (Eds.), Psychophysiology: systems, processes, and applications ( pp. 611 ± 625). New York: Guilford Press. Powell, D. A., Milligan, W. L., & Furchtgott, E. (1980). Peripheral autonomic changes accompanying learning and reaction time performance in older people. Journal of Gerontology, 35, 57 ± 65. Rapee, R. (1985). A distinction between panic disorder and generalized anxiety disorder: clinical presentation. Australian and New Zealand Journal of Psychiatry, 19, 227 ± 232. Regier, D. A., Boyd, J. H., Burke, J. D., Rae, D. S., Myers, J. K., Kramer, M., Robins, L. N., George, L. K., Karno, M., & Locke, B. Z. (1988). One-month prevalence of mental disorders in the United States: based on five epidemiologic catchment area sites. Archives of General Psychiatry, 45, 977 ± 986. Shapiro, D., Jamner, L. D., Lane, J. D., Light, K. C., Myrtek, M., Sawada, Y., & Steptoe, A. (1996). Blood pressure publication guidelines. Psychophysiology, 33, 1 ± 12. Shmavonian, B. M., Yarmat, A. J., & Cohen, S. I. (1965). Relationships between the autonomic nervous system and central nervous system in age differences in behavior. In: A. T. Welford, & J. E. Birren (Eds.), Behavior, aging, and the nervous system: biological determinants of speed of behavior and its changes with age ( pp. 235 ± 258). Springfield, IL: Charles C Thomas. Shmavonian, B. M., Miller, L. H., & Cohen, S. I. (1968). Differences among age and sex groups in electrodermal conditioning. Psychophysiology, 5, 119 ± 131.

630

A.W. Lau et al.

Shmavonian, B. M., Miller, L. H., & Cohen, S. I. (1970). Differences among age and sex groups with respect to cardiovascular conditioning and reactivity. Psychophysiology, 5, 87 ± 94. Silverman, A. J., Cohen, S. I., & Shmavonian, B. M. (1958). Psychophysiological response specificity in the elderly. Journal of Gerontology, 13, 443. Spielberger, C. D., Gorsuch, R. L., & Lushene, R. E. (1970). Manual for the state ± trait anxiety inventory. Palo Alto: Consulting Psychologists Press. Stone, J. L., & Norris, A. H. (1966). Activities and attitudes of participants in the Baltimore Longitudinal Study. Journal of Gerontology, 21, 575 ± 580. Turpin, G. (1991). The psychophysiological assessment of anxiety disorders: three-systems measurement and beyond. Psychological Assessment, 3, 366 ± 375. U.S. Senate Special Committee on Aging, American Association of Retired Persons, Federal Council on the Aging, and U.S. Administration on Aging. (1991). Aging America: trends and projections. Washington, DC: Department of Health and Human Services. Zuckerman, M. (1991). Psychobiology of personality. Cambridge, MA: Cambridge Univ. Press.