Integrating Anxiety Sensitivity, Distress Tolerance, and Discomfort Intolerance: A Hierarchical Model of Affect Sensitivity and Tolerance

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Behavior Therapy 40 (2009) 291 – 301

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Integrating Anxiety Sensitivity, Distress Tolerance, and Discomfort Intolerance: A Hierarchical Model of Affect Sensitivity and Tolerance Amit Bernstein, University of Haifa Michael J. Zvolensky, Anka A. Vujanovic, The University of Vermont Rudolf Moos, Center for Health Care Evaluation, VA Palo Alto Health Care System, and Stanford University School of Medicine

The purpose of the present investigation was to concurrently examine the latent dimensional and hierarchical structure of anxiety sensitivity (AS) and two key theoretically relevant and related affect (in)tolerance and sensitivity constructs: distress tolerance and discomfort intolerance. These constructs were measured using the Anxiety Sensitivity Index (Reiss, Peterson, Gursky, & McNally, 1986), the Distress Tolerance Scale (Simons & Gaher, 2005), and the Discomfort Intolerance Scale (Schmidt, Richey, & Fitzpatrick, 2006). A total of 229 individuals (124 females; M age = 21.0 years, SD = 7.5) without current Axis I psychopathology participated by completing a battery of self-report questionnaires. A two-stage exploratory factor analysis was conducted to examine the lower- and higher-order latent structural relations among the variables. The factor solution was subsequently evaluated in relation to negative affectivity, anxious arousal, and anhedonic depression. AS and

This work was supported by a National Research Service Award (F31 MH073205-01) awarded to Amit Bernstein. Dr. Bernstein also acknowledges that this research was supported in part by VA Office of Academic Affairs and Health Services Research and Development Service Research funds. This paper also was supported by National Institute on Drug Abuse research grants (1 R01 MH076629-01, 1 R01 DA018734-01A1, and R03 DA16307-01) awarded to Dr. Zvolensky and a National Research Service Award (1 F31 DA021006-01) granted to Anka A. Vujanovic. Address correspondence to Amit Bernstein, Ph.D., Department of Psychology, University of Haifa, Mount Carmel, Haifa, Israel 31905; e-mail: [email protected]. 0005-7894/08/0291–0301$1.00/0 © 2008 Association for Behavioral and Cognitive Therapies. Published by Elsevier Ltd. All rights reserved.

distress tolerance appeared to be related to one another as distinct lower-order facets of a common higher-order affect tolerance and sensitivity factor, whereas discomfort intolerance did not appear to demonstrate similar relations with either AS or distress tolerance at the lower-order or higherorder levels. A unique pattern of association with theoretically-relevant criterion variables was observed between the affect tolerance and sensitivity higher-order factor, the AS and distress tolerance lower-order factors, and the discomfort intolerance factor. Findings are discussed in the context of theoretical and clinical implications and future directions for the study of affect tolerance and sensitivity in relation to emotional vulnerability.

ANXIETY SENSITIVITY (AS) is the fear of anxiety and arousal-related sensations (Reiss & McNally, 1985). When anxious, individuals high in AS become acutely fearful, believing that these anxiety sensations have harmful physical, psychological, and/or social consequences, and tend to cope with such stress in a rigid (inflexible), avoidant fashion (Kashdan, Zvolensky, & McLeish, 2008; McNally, 2002; Rodriguez, Bruce, Pagano, Spencer, & Keller, 2004; Taylor, 1999; Zinbarg & Barlow, 1996). AS is significantly associated with an increased risk for anxiety symptoms, panic attacks, and certain anxiety and mood disorders (Feldner, Zvolensky, Schmidt, & Rose-Smith, 2008; Hayward, Killen, Kraemer, & Taylor, 2000; Li & Zinbarg, 2007; Maller & Reiss, 1992; Schmidt, Lerew, & Jackson, 1997, 1999; Schmidt, Zvolensky, & Maner, 2006). Other work suggests that reducing levels of AS is related to

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improved levels of psychological functioning among clinical and nonclinical populations (Otto & ReillyHarrington, 1999; Schmidt, Eggleston, et al., 2006; Smits, Powers, Cho, & Telch, 2004). In an effort to elucidate the theoretical and structural boundaries of AS and clarify how AS is distinct from other potentially similar psychological constructs, pioneering work was aimed at clarifying the unique explanatory value of AS in relation to a more global tendency to experience anxiety symptoms and negative affective states (e.g., Rapee & Medoro, 1994). Studies have indicated AS is distinct from a temperamental tendency to experience negative affect (negative affectivity) and the frequency of anxiety symptoms (trait anxiety; Zinbarg, Brown, Barlow, & Rapee, 2001; Zvolensky, Kotov, Antipova, & Schmidt, 2005). By comparison, considerably less attention has been focused on examining the latent structure of AS, and its relations with and distinctiveness from other psychological constructs that focus on a sensitivity to, or intolerance of, aversive somatic and affective states. This gap in the AS literature calls for further empirical work focused on (a) elucidating the differences and similarities between AS and other affect tolerance and sensitivity constructs, and (b) clarifying the structural relations between AS and these constructs (Bernstein & Zvolensky, 2007). This empirical gap potentially hampers advances in theoretical models of emotional vulnerability and clinical assessment and prevention/treatment efforts targeting these putative factors. During the time that the AS literature grew firm roots in the study and treatment of anxiety and mood-based psychopathology (Bernstein & Zvolensky, 2007; McNally, 2002; Taylor, 1999), increasing scientific and clinical interest has focused on the role of emotional (in)tolerance and sensitivity (defined below) in the etiology and maintenance of various forms of psychopathology (Gross, 1998; Hayes, Wilson, Gifford, Follette, & Strosahl, 1996; Rottenberg, 2005; Rottenberg & Gross, 2007; Zvolensky & Otto, 2007). Similar to the AS literature, many of these empirical accounts are concerned with the amplification of negative emotional experiences and the impairment that may result from the inflexible utilization of avoidant emotional control strategies. For example, the tendency to be sensitive to and intolerant of one’s internal thoughts and emotions is theorized to amplify negative affect in models of depression (Gross & Munoz, 1995), generalized anxiety disorder (Mennin, Heimberg, Turk, & Fresco, 2002), panic disorder (Kashdan et al., 2008), and borderline personality disorder (Gratz, Tull, & Gunderson, 2008). Additionally, emotional sensi-

tivity and intolerance of aversive interoceptive stimuli (e.g., withdrawal symptoms) have been hypothesized as important explanatory processes for understanding lapse and relapse effects in substance use and dependence (Brandon et al., 2003; Brown, Lejuez, Kahler, Strong, & Zvolensky, 2005; Chaney, Roszell, & Cummings, 1982; Otto, Powers, & Fischmann, 2005; Zvolensky & Bernstein, 2005). The increase in these studies has been matched by the growth of psychosocial interventions designed to promote affect tolerance and related processes, such as emotional acceptance (Barlow, Allen, & Choate, 2004; Hayes, Strosahl, & Wilson, 1999; Linehan, 1993; Marlatt, 2002; Teasdale, Segal, & Williams, 1995). Given the potential overlap between AS and other emotional intolerance and sensitivity constructs, it remains a central task to clarify their structural relations to one another. Better understanding of the structural relations among these associated constructs has the potential to: (a) elucidate processes relevant to emotional vulnerability, (b) better match the clinical conceptualization and measurement models of these constructs to their latent structure, and (c) guide clinical interventions targeting these vulnerability factors. Indeed, as of yet, research has not clarified how—at the latent level of analysis— AS is distinct from and related to other emotional sensitivity and tolerance constructs. Therefore, a programmatic next step in this line of inquiry involves the empirical evaluation of whether AS and other emotional sensitivity and tolerance factors are distinct from one another at a latent level of analysis. Distress tolerance is one construct relevant to sensitivity to and tolerance of aversive affective stimuli in need of empirical scrutiny in regard to AS (Simons & Gaher, 2005). Simons and Gaher (2005) developed the Distress Tolerance Scale (DTS) to measure participants’ (perceived) ability to experience and endure negative emotional states. Factor analytic study of the DTS has indicated that the scale measures appraisal (e.g., “Being distressed or upset is always a major ordeal for me”), tolerance (e.g., “I can’t handle feeling distressed or upset”), absorption (e.g., “When I feel distressed or upset, all I can think about is how bad I feel”), and regulation (e.g., “I’ll do anything to avoid feeling distressed or upset”) dimensions of the distress tolerance construct. Elevated scores on the DTS are concurrently related to greater positive affect and to less affective distress and lability (Simons & Gaher, 2005) and less coping-oriented substance use (Simons, Gaher, Oliver, Bush, & Palmer, 2005). Additionally, higher distress tolerance is related to lower levels of eating psycho-

affect sensitivity and tolerance pathology, anxiety and depressive symptoms, as well as less problematic substance use (Anestis, Selby, Fink, & Joiner, 2007; O’Cleirigh, Ironson, & Smits, 2007; Simons et al., 2005). Thus, lower levels of distress tolerance, as measured by the DTS, are related to a variety of negative psychological symptoms and outcomes. Yet, the extent to which distress tolerance is structurally related to or distinct from AS is presently unclear. An additional construct of theoretical relevance to AS is discomfort intolerance (Schmidt, Richey, & Fitzpatrick, 2006), which reflects the (lack of) capacity to withstand uncomfortable physical sensations (Schmidt & Lerew, 1998). Theorizing regarding this construct led to the development of the Discomfort Intolerance Scale (DIS; Schmidt, Richey, et al., 2006). The DIS is comprised of a higher-order discomfort intolerance factor and two lower-order factors entitled Intolerance of Discomfort or Pain (e.g., “I can tolerate a great deal of physical discomfort”—reverse scored) and Avoidance of Physical Discomfort (e.g., “I take extreme measures to avoid feeling physically uncomfortable”; Schmidt, Richey, et al., 2006). The DIS has evidenced acceptable psychometric properties (e.g., high internal consistency and convergent and discriminant relations with other established constructs; Schmidt, Richey, et al., 2006). A number of studies indicate that discomfort intolerance may be a risk factor for anxiety psychopathology (Schmidt, Richey, Cromer, & Buckner, 2007; Schmidt et al., 2006). For example, Schmidt and colleagues (2007) found that the global discomfort intolerance construct (DIS total score) was incrementally predictive of post-challenge self-reported anxiety during biological challenge (i.e., carbon dioxideenriched air provocation), above and beyond the variance accounted for by trait anxiety and AS. However, it is not yet clear whether, or how, the latent structure of discomfort intolerance is structurally related to AS. The purpose of the present study was to examine the latent structure of AS in the context of distress tolerance and discomfort intolerance. Broadly, it was expected that individual differences in AS would covary with individual differences in tolerance for similar affective states (distress tolerance) and that these associations would be accounted for by a higher-order latent factor encompassing these related, but distinct, factors. This prediction was driven by the idea that AS reflects sensitivity to, and distress tolerance reflects tolerance of, aversive emotional states (Carleton, Sharpe, & Asmundson, 2007; Simons & Gaher, 2005; Taylor, 1999). Specifically, it was predicted that exploratory factor analysis would demonstrate a multi-dimensional

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factor solution—consistent with theory that AS, discomfort intolerance, and distress tolerance are distinct latent variables. This hypothesis was informed by previous work, which suggests that there is unique explanatory value to each of these constructs (Schmidt et al., 2007; Simons & Gaher, 2005; Zinbarg et al., 2001). Second, it was hypothesized that AS and distress tolerance factors would be related to one another, whereas discomfort intolerance ([in]tolerance for physical sensations) would not be related to either of these (affect-related) variables. The rationale for this hypothesis is that sensitivity to and tolerance of affect-related states reflects a theoretically distinct process from sensitivity to and tolerance of physical discomfort, which may not be directly linked to affect or emotion (Bernstein & Zvolensky, 2007). Finally, we hypothesized that a global, higher-order factor would account for the association between (affect-related) AS and distress tolerance and that this higher-order factor would not encompass discomfort intolerance. This hypothesis was informed by findings showing that various facets of emotion regulation and related factors may be connected with one another hierarchically (Mennin et al., 2007). Furthermore, we theorized that similar, and perhaps shared, processes, impact and thereby account for the predicted relations between sensitivity to and tolerance of similar affective states. For example, individuals who are sensitive to anxiety may also be intolerant of and motivated to avoid such affective states; and in so far as individuals are intolerant of aversive affective states such as anxiety, they may also be more sensitive to such affective states.

Method participants A total of 229 participants (124 females; M age = 21.0 years, SD = 7.5) were recruited via announcements in university classes, flyers placed in public spaces throughout the greater Burlington, VT community, and advertisements in local newspapers. Advertisements focused on recruitment for a laboratory study on emotion for monetary reward (see Procedure section for details). The racial distribution of the sample generally reflected that of the Vermont population (State of Vermont Department of Health, 2007): 92.6% percent of the total sample identified as Caucasian, 0.4% as African-American, 1.7% as Hispanic, 0.9% as Asian, 1.3% as bi- or multiracial, 0.9% as “other,” and 2.2% did not provide race/ ethnicity data. In terms of highest level of education completed, 0.4% of participants reported not graduating from high school, 80.6% reported graduating from high school, 13.7% reported

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partial college education, 1.3% reported graduating from a 2-year college, 2.2% reported graduating from a 4-year college, 0.9% reported partial graduate education, and 0.9% reported completing graduate school. Exclusionary criteria for the investigation included: (1) current Axis I psychopathology; (2) current use of psychotropic medication; (3) current suicidality or homicidality; (4) current or past chronic cardiopulmonary illness (e.g., chronic obstructive pulmonary disease; severe asthma); (5) current acute respiratory illness (e.g., bronchitis); (6) seizure disorder, cardiac dysfunction, or other serious medical illness (e.g., history of seizures, emphysema); (7) pregnancy (females); and (8) limited mental competency or inability to give written, informed consent. Due to the preliminary, exploratory nature of the current study, individuals with current Axis I psychopathology were excluded to ensure that the observed effects and structural relations were not potentially confounded by the symptoms of clinical syndromes that covary with the vulnerability factors of AS, distress tolerance, and discomfort intolerance (Schmidt et al., 2006). It is important at this early stage in the development of this research to ensure that study of such basic constructs initially rule out the possibility that cooccurring psychopathology confound, or account for, the observed associations, or lack thereof, between such vulnerability factors. Most notably, all three of the studied variables are theorized to function as vulnerability factors and to be expressed and clinically important, prior to the development of psychopathology. Consequently, it is important to examine the research question at hand among a psychiatrically healthy sample. Also, a number of additional exclusionary criteria were utilized (e.g., exclusion of those with chronic cardiopulmonary illness or current acute respiratory illness) due to other experimental tasks that participants completed following completion of the studied measures in the present investigation (Bernstein, Zvolensky, Marshall, & Schmidt, 2009).

measures Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders – 4th Edition (DSM-IV) Axis I Diagnoses/Non-Patient Version (SCID-I/NP). Diagnostic exclusion for current axis I diagnoses was determined using the SCID-I/NP (SCID-I/NP; First, Spitzer, Gibbon, & Williams, 1995). The nonpatient version was used since participants were not identified as a clinical sample. The DSM-IV version of the SCID-I/NP has good reliability (interrater Kappa = .63 – 1.0; test-retest Kappa = .44 - .78, Zanarini et al., 2000) and good

to excellent validity (Basco et al., 2000). The SCID was administered by trained graduate-level interviewers. Interrater reliability in prior investigations by our team has been excellent for Axis I diagnoses (e.g., Zvolensky, Feldner, et al., 2005), and this screening approach has been used successfully in past work (e.g., Zvolensky, Eifert, & Lejuez, 2001). In the present study, each SCID interview was reviewed by the principal investigator to ensure interrater agreement; no disagreements regarding inclusion/exclusion were observed. Medical exclusionary criteria, including psychotropic mediation usage, were assessed within the context of the SCID interview, using a supplemental set of standardized and previously employed interview-based medical screening questions. Anxiety Sensitivity Index (ASI; Reiss, Peterson, Gursky, & McNally, 1986). The ASI is a 16-item measure in which respondents indicate, on a 5-point Likert-type scale (0 = very little to 4 = very much), the degree to which they are concerned about possible negative consequences of anxiety symptoms. The ASI has three first-order factors entitled AS–Physical Concerns, AS–Mental Incapacitation Concerns, and AS–Social Concerns and a single, higher-order general factor (Zinbarg, Barlow, & Brown, 1997). Greater scores reflect higher levels of anxiety sensitivity. The ASI is scored as a single sum across all items, and the total score may range from 0 to 64. The ASI has high internal consistency ranging from .84 for a sample of college students to .88 – .90 for a clinical sample of anxiety-disordered patients (Reiss et al., 1986) and good test-retest reliability (kappa = .75). The ASI has demonstrated excellent convergent validity (r N.70) with other established anxiety-relevant measures (Peterson & Reiss, 1992; Zinbarg, Mohlman, & Hong, 1999); and it is unique from, and demonstrates incremental predictive validity relative to, trait anxiety (McNally, 1996) and negative affectivity (Zvolensky, Kotov, et al., 2005). Distress Tolerance Scale (DTS; Simons & Gaher, 2005). The DTS is composed of 14 items answered on 5-point Likert-type scales ranging from (1) strongly agree to (5) strongly disagree that evaluate participants’ ability to experience and endure negative emotional states. Greater scores reflect higher levels of distress tolerance. This scale has good psychometric properties, including high internal consistency (α = .89) and appropriate convergence with other self-report ratings of affective distress and regulation (Simons & Gaher, 2005). In addition, the DTS has demonstrated adequate 6month test-retest reliability (r = .61; Simons & Gaher, 2005). The scale incorporates items that assess appraisal, tolerance, absorption, and regula-

affect sensitivity and tolerance tion. The present investigation utilized the original 14-item scale; the final, published scale is identical to the one utilized except that it includes a 15th item. Because the 14- and 15-item versions of the DTS differ by only by one item, their psychometric properties are very similar (Simons & Gaher, 2005). Discomfort Intolerance Scale (DIS; Schmidt, Richey, et al., 2006). The DIS is a 5-item measure on which participants indicate, on 7-point Likerttype scales (0 = not at all like me to 6 = extremely like me), their agreement with statements related to their intolerance of physically relevant discomfort. Greater scores reflect lower levels of discomfort tolerance (i.e., higher scores reflect higher levels of discomfort intolerance). Aside from a global score, factor analysis indicates that the DIS is comprised of two distinct subfactors, entitled Intolerance of Discomfort or Pain and Avoidance of Physical Discomfort. The DIS has good internal consistency with alpha coefficients of .92 for the Intolerance subscale, .78 for the avoidance subscale, and .70 for the total scale score (Schmidt, Richey, et al., 2006). Positive Affect Negative Affect Scale (PANAS; Watson, Clark, & Tellegen, 1988). The PANAS is a mood measure that assesses two global dimensions of affect: negative and positive. Both the negative affectivity and the positive affectivity scales of the PANAS have demonstrated high levels of internal consistency across a range of populations, including cross-national samples (range of alpha coefficients: .83 – .90 and .85 – .93, respectively; see Watson, 2000). The PANAS has also demonstrated good testretest reliability (r = .71; Watson et al., 1988). The negative affectivity subscale was used as an index of the disposition to experience negative affective states (e.g., anger, anxiety, depression, guilt). Mood and Anxiety Symptoms Questionnaire (MASQ; Watson et al., 1995). The MASQ is a measure of affective symptoms. Participants indicate how much they have experienced each symptom on a 5-point Likert-type scale (1 = not at all to 5 = extremely). The Anxious Arousal scale (MASQ-AA) measures the symptoms of somatic tension and arousal. The Anhedonic Depression scale (MASQ-AD) measures a loss of interest in life. The MASQ shows excellent convergence with other measures of anxiety and depression (Watson et al., 1995). The MASQ-AA and MASQ-AD subscales were used in the present investigation as indices of anxiety and depressive symptoms.

procedure Interested persons responding to advertisements who contacted the research team were given a detailed description of the study over the phone.

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After providing verbal consent, the SCID-I/NP was administered by a trained research assistant via telephone. Those meeting inclusionary criteria were scheduled to attend a single session. Upon arrival to the laboratory, participants completed a written informed consent form. Participants then completed the self-report measures. Participants also later participated in a laboratory-portion of the study involving biological challenge that is not included as part of this report. After the study, participants were debriefed and compensated $20 for their time.

data analytic plan A two-stage exploratory factor analysis (EFA) was conducted. First, a principal axis factor analysis (PAF) with an oblique rotation was used to test the factor structure of ASI, DTS, and DIS items that were combined into a single item-pool. Second, lower-order factors derived from the initial itemlevel PAF were examined in a hierarchical principal axis factor analysis with an orthogonal rotation to examine the possible higher-order factor structure of these factors. Following factor analyses, the derived factor solution was evaluated in relation to theoretically relevant criterion variables. Specifically, to evaluate the relations between the identified latent factors and key theoretically relevant criterion variables, zero-order correlations between the lower and higher-order factor scores and negative affectivity, anxious arousal, and anhedonic depressive symptoms were conducted. Additionally, effect size estimates of the conducted correlations were completed in order to explicate the sizes of the putative differential magnitude of the observed correlations (Cohen, 1988).

Results factor analyses First, a PAF with an oblique rotation was conducted to identify the latent factor structure of the ASI, DTS, and DIS items that were combined into a single item-pool. An oblique rotation was used in line with first-order EFA guidelines for the study of theoretically related, and potentially covarying, variables (Gorsuch, 1983). Extraction of three factors was indicated by visual inspection of the Scree Plot (Cattell, 1966). PAF pattern matrices (loadings) and communalities of the 3-factor solution are shown in Table 1. ASI Items 5 (“It is important to me to stay in control of my emotions”), 13 (“Other people notice when I feel shaky”), and 15 (“When I am nervous, I worry that I might be mentally ill”) were omitted empirically from the factor solution because of hyperplane or

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Table 1

Loadings and Extraction Communalities for the Three-Factor Solution: Distress Tolerance, Anxiety Sensitivity, Discomfort Intolerance Factors H2

Loadings

DTS 1 DTS 2 DTS 3 DTS 4 DTS 5 DTS 6⁎ DTS 7 DTS 8 DTS 9 DTS 10 DTS 11 DTS 12 DTS 13 DTS 14 ASI 1 ASI 2 ASI 3 ASI 4 ASI 5 ASI 6 ASI 7 ASI 8 ASI 9 ASI 10 ASI 11 ASI 12 ASI 13 ASI 14 ASI 15 ASI 16 DIS 1⁎ DIS 2⁎ DIS 3 DIS 4 DIS 5

Factor I

Factor II

Factor III

.59 .67 .65 .70 .60 .38 .43 .47 .68 .81 .63 .64 .61 .74 −.09 −.12 .09 .16 −.20 .05 −.06 .13 .03 −.02 .10 −.13 −.15 −.05 −.14 −.15 .03 .02 −.16 −.11 −.13

−.08 −.08 −.08 .00 .01 .00 .01 .03 .08 .07 −.02 −.04 .05 −.01 .37 .45 .68 .75 .25 .64 .41 .62 .46 .52 .54 .48 .22 .61 .29 .48 .02 .03 .09 .05 .08

.01 .04 −.03 .00 .04 −.07 .04 −.06 −.11 .06 .03 −.09 −.08 −.02 −.17 −.03 .00 .09 −.22 .03 .11 .08 .01 .06 .10 −.08 .03 −.01 −.08 .05 .79 .83 .37 .48 .62

.39 .49 .47 .49 .35 .16 .18 .22 .45 .61 .41 .45 .37 .56 .18 .26 .42 .52 .17 .39 .22 .35 .20 .29 .28 .29 .10 .40 .13 .32 .63 .69 .21 .27 .45

Note. Salient loadings (near or N.40) are in boldface. ASI = Anxiety Sensitivity Index. DTS = Distress Tolerance Scale. DIS = Discomfort Intolerance Scale. ⁎ = reverse scored items.

non-vocal loadings (i.e., items failing to have a loading N .40). ASI Item 1 (factor loading = .37), DTS Item 6 (factor loading = .38), and DIS Item 3 (factor loading = .37) were retained in their respective factors because their univocal item-factor loadings approximated the (arbitrary) .40 cutoff. Thus, 13 of the 16 ASI items (except Items 5, 13, 15), all 14 DTS items, and all 5 DIS items demonstrated statistically robust and univocal item-factor loadings (N.40) and were therefore retained in the factor solution. The multidimensional factor solution was composed of the three lower-order factors: an anxiety sensitivity factor, a

distress tolerance factor, and a discomfort intolerance factor. In addition to the visual inspection of the Scree Plot, parallel analysis was conducted as a consistency test for the purpose of factor extraction (Horn, 1965; O’Connor, 2000). Parallel analysis based on the random permutation of the raw data (matched to the item/variable distributions) of the unrotated solution indicated that up to 5 nonspurious factors may be extracted. Specifically, 5 factors among the research data were greater than the 95th percentile random data eigenvalues, indicating that up to five factors may be extracted from the research data that could represent substantive, nonspurious factors. To evaluate the empirical and theoretical interpretability of a 5-factor solution, in comparison to a 3-factor solution, the PAF was reconducted to extract five factors. Three of the 5 factors were statistically retainable and theoretically interpretable, and were very similar to the 3factor solution indicated by the Scree Plot test. Factor IV demonstrated only one univocal item with a factor loading N.40. Moreover, 4 of the 5 items that loaded on to Factor IV demonstrated weak factor loadings (b.40), and three of those 4 items were multivocal with stronger loadings on Factors I, II, or III. Similarly, Factor V demonstrated only one univocal item with a robust factor loading (N.40). Moreover, three other items demonstrated weak loadings (b.40), each of which were multivocal with similar or stronger loadings on Factors I, II, and III. It also is noteworthy that items loading onto Factors IV and V were not interpretable subscales of the ASI, DTS, or DIS, and unlike Factors I, II and III, consisted of a mixture of ASI, DTS, and DIS items, as opposed to interpretable sub-scales observed in previous factor analytic studies of each of these measures. Therefore, in light of: (a) the threat of overextraction in parallel analysis, (b) the clear pattern of item-factor loadings obtained for the three-factor solution, (c) the number of factors extracted by the Scree Plot test, and (d) the theoretically interpretable and empirically sound 3-factor solution, the 3-factor solution was retained. Results of the parallel analysis confirm that the 3 retained factors were likely substantive and non-spurious. The 3-factor solution explained a large percent of variance (40.3%) consistent with a good-fitting solution (Gorsuch, 1983). Distress tolerance and AS factors were moderately negatively correlated (r = -.41); the discomfort intolerance factor was not significantly correlated with the distress tolerance factor (r = -.12) or the AS factor (r = .14). Next, we ran a hierarchical PAF analysis using an orthogonal rotation of the 3 factor scores derived

affect sensitivity and tolerance Table 2

Loadings and Extraction Communalities for the Unidimensional Higher-Order Factor Solution

Anxiety Sensitivity Factor Distress Tolerance Factor Discomfort Intolerance Factor

Loadings Factor I

H2

.74 −.61 .23

.55 .37 .05

Note. Salient loadings (near or N.40) are in boldface.

via the regression method from the item-level PAF. The orthogonal rotation was used in line with guidelines for the conduct of second-order EFA (Gorsuch, 1983). One higher-order factor was extracted based on the evaluation of the Scree Plot (Cattell, 1966). Parallel analysis based on the random permutation of the raw data (matched to the item/variable distributions) of the unrotated solution also indicated a unidimensional solution. Specifically, the single factor among the research data factor scores was greater than the 95 th percentile random data eigenvalue, indicating that the single factor extracted from the research data represented a substantive, nonspurious higherorder factor. PAF pattern matrices (loadings) and communalities of the one higher-order factor solution are shown in Table 2, which we have designated and labeled as affect sensitivity and tolerance. The AS factor and the distress tolerance factor loaded as lower-order factors onto one higher-order factor (factor loadings = .74, -.61, respectively). In contrast, the discomfort intolerance factor did not meaningfully load onto the higher-order factor (factor loading = .23), consistent with the pattern of correlations observed between the lower-order factors and with theoretical prediction. Finally, the 1-factor solution explained a large percent of variance (51.3%; Gorsuch, 1983). Consistent with the 1-factor solution, when the hierarchical PAF was reconducted with only the distress tolerance and AS factors, the 1-factor solution explained a larger percent of variance (72.6%).

construct validity analyses The higher-order affect sensitivity and tolerance factor as well as the lower-order distress tolerance and AS factors and independent discomfort intolerance factor, were evaluated in relation to negative affectivity, as well as anxious arousal and anhedonic depressive symptoms. For these analyses, greater scores on the higher-order affect sensitivity and tolerance factor reflect greater tolerance and less sensitivity (i.e., lower scores on the higher-order factor reflect intolerance and greater sensitivity). Negative affectivity demonstrated moderate to

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large associations with the higher-order affect sensitivity and tolerance factor (r = -.47, p b .01, r2 = .22) and the lower-order distress tolerance (r = .43, p b .01, r2 = .18) and AS factors (r = .37, p b .01, r 2 = .14). The discomfort intolerance factor, in contrast, was not significantly correlated with negative affectivity (r = .15, p N .01, r 2 = .02). Anxious arousal symptoms demonstrated a moderate association with the higher-order affect sensitivity and tolerance factor (r = -.26, p b .01, r2 = .07), a moderate association with the lowerorder AS factor (r = .25, p b .01, r2 = .06), and a small association with the lower-order distress tolerance factor (r = -.19, p b .01, r 2 = .04). The discomfort intolerance factor was not significantly correlated with anxious arousal (r = .00, p N .01, r2 = .00). Anhedonic depressive symptoms demonstrated a moderate association with the higherorder affect sensitivity and tolerance factor (r = -.37, p b .01, r2 = .14), a large association with the lowerorder distress tolerance factor (r = -.46, p b .01, r2 = .21), a small association with the lower-order AS factor (r = .18, p b .01, r2 = .03), and an equally small association with the discomfort intolerance factor (r = .18, p b .01, r2 = .03).

Discussion AS is an important explanatory factor for disorders of emotion by promoting amplified affective reactions and avoidance-oriented coping with aversive stimuli (see Bernstein & Zvolensky, 2007; Taylor, 1999; McNally, 2002, for reviews). In addition, distress intolerance and discomfort intolerance may reflect psychological constructs that also serve to amplify emotional reactions and escape and avoidance behavior to emotional and somatic cues (Schmidt et al., 2007; Simons & Gaher, 2005). Despite possible overlap in these constructs, there has not yet been empirical exploration of their latent structural relations. Yet, this type of latent structural work is necessary to clarify our understanding of these clinically relevant constructs, to delineate related vulnerability processes, as well to improve assessment and treatment development work targeting these vulnerability processes. To fill this gap in the extant literature, the purpose of the present investigation was to concurrently examine the dimensional and hierarchical latent structure of AS, distress tolerance, and discomfort intolerance. Results indicated that AS, distress tolerance, and discomfort intolerance demonstrated a multidimensional 3-factor solution. These findings are in accord with the theoretical bases of each of the studied constructs (McNally, 2002; Schmidt et al., 2007; Simons & Gaher, 2005). Anxiety sensitivity

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and distress tolerance appear to be related to one another as lower-order facets of the same higherorder factor. In contrast, discomfort intolerance does not appear to demonstrate similar relations with either AS or distress tolerance at the lower- or higher-order levels. These data suggest that these sensitivity and tolerance factors related to affective states are structurally distinct at the latent level of analysis. Thus, these factors should be considered distinct factors in the context of theoretical models of psychopathology and clinical interventions addressing them. Although distinct, these data also indicate that AS and distress tolerance may be related, lowerorder factors of the same higher-order affect sensitivity and tolerance factor. This novel finding thus suggests that AS and distress tolerance, as measured by the ASI and DTS, share a common, higher-order factor that accounts for covarying individual differences in sensitivity to and intolerance of negative affective states. In contrast, discomfort intolerance, as indexed by the DIS, appears to be a structurally distinct construct that may not be substantively related to AS or distress tolerance. It is theoretically possible that sensitivity to and tolerance of affective states reflect unique and distinct processes from sensitivity to and intolerance of physical discomfort and related bodily sensations that may not be linked to affect or emotion. Subsequent analyses indicated an informative pattern of associations between the identified factors and the external criteria. The higher-order affect sensitivity and tolerance factor encompassing AS and distress tolerance lower-order factors demonstrated a large-sized association with negative affectivity (r2 = .22), and medium-sized associations with anhedonic depressive symptoms (r2 = .14) and anxious arousal (r2 = .07). The lower-order AS factor demonstrated medium-sized associations with negative affectivity (r 2 = .14) and anxious arousal (r2 = .06), and a small-sized association with anhedonic depressive symptoms (r 2 = .03). Moreover, the lower-order distress tolerance factor demonstrated large-sized associations with negative affectivity (r 2 = .18) and anhedonic depression (r2 = .21), and a small-sized association with anxious arousal (r2 = .04) (Cohen, 1988). In contrast, the discomfort intolerance factor was not substantively related to either negative affectivity (r2 = .02) nor to anxious arousal (r 2 = .00) and demonstrated a statistically significant but small-sized association with anhedonic depressive symptoms (r2 = .03). These findings point to the potential theoretical and clinical import of studying AS in the context of other affect sensitivity and tolerance constructs. In

this regard, these findings collectively provide preliminary evidence of the construct validity of the putative higher-order latent variable encompassing AS and distress tolerance in terms of negative affective states and symptoms. Further, the data point to the potential theoretical and clinical utility of examining the relations between the identified higher-order factor and other outcomes of interest (e.g., anxiety psychopathology and substance use problems) in an independent sample. In light of the fact that the association between the higher-order factor and broad-based negative affectivity was approximately three times greater in effect size relative to its association with the more specific anxious arousal symptoms (i.e., r2 = .22 versus r2 = .07), further study of this factor may demonstrate broad-based and perhaps transdiagnostic relations beyond specific anxiety disorders such as panic. Moreover, these findings also suggest that, although AS and distress tolerance may reflect lower-order factors of a common higher-order variable, these lower-order factors may demonstrate distinct relations with outcomes of interest and therefore also merit attention in their own right. Finally, these data suggest that further empirical scrutiny should be paid to the specificity of discomfort intolerance and its nomological network. One possibility worthy of examination is that discomfort intolerance may be more closely associated with somatic problems and/or to panicrelated problems, as documented in previous studies of the construct (Schmidt et al., 2006, 2007), than with more broad-based affective symptoms and disorders. Beyond the need for independent replication, the present study has a number of limitations that deserve further comment. First, the present sample was comprised of a relatively (demographically) homogeneous group of young adults. To increase the generalizability of these findings, it will be important to draw from populations beyond those used in the present study. Furthermore, the current sample was not a representative sample or drawn from a clinical population. Future work should evaluate the generalizability of the present structural model by extending tests of it to representative population samples as well as to specific clinical populations (e.g., persons with anxiety psychopathology). Second, although the present investigation examined three well-established affect sensitivity and tolerance factors in the psychopathology literature, other putative risk factors may warrant similar structural examination (e.g., affect intensity). Such study may have theoretical and clinical promise for advancing ecologically valid, multirisk factor models that can be applied to

affect sensitivity and tolerance understanding the enigmas of psychopathology, such as the malleable mechanisms underlying its etiology and maintenance. Furthermore, it may be that the identified higher-order variable reflects (affect-related) factors beyond anxiety sensitivity and distress tolerance, although such factors were not examined in the present investigation. Thus, the latent nature of the higher- and lower-order structure of this construct and related facets could theoretically be broader than indicated by the present investigation and warrants future study. In addition, it is noteworthy that there is currently no published measure of discomfort sensitivity. Thus, in the current study, although we were able to measure AS, distress tolerance, and discomfort intolerance, we were not able to directly and specifically measure sensitivity to discomfort. Such a variable, which may or may not be theoretically or clinically meaningful or independent from discomfort intolerance, could possibly have impacted the results of the present investigation. Future work may thus usefully consider whether, for example, a second higher-order variable composed of sensitivity and tolerance of discomfort would be observed. Third, the present investigation utilized established self-report instruments. Though this approach is prudent at this stage of research development, future work might build upon the present findings and incorporate multimethod approaches to measurement of the variables of interest. Furthermore, the findings may reflect not only substantive relations between putative latent variables, but measurement problems and limitations of the measures to fully reflect these constructs as well. Consequently, further study of these constructs and their relations using multiple measurement approaches is important. Fourth, due to the cross-sectional and correlational nature of the present research, it is not possible to make causal statements concerning any of the observed relations among the studied constructs or their relations with external criteria such as negative affectivity and anxiety and depressive symptoms. One important next step is to prospectively evaluate the temporal and developmental pattern of their relations over time. Fifth, the sample size in the present EFA study was relatively small in light of the number of items in the studied measures. Therefore, the stability of the identified factor solution should be replicated and evaluated with confirmatory factor analysis. However, it is important to note that the second-order EFA involved a case-to-variable ratio well in the traditionally recommended range (n = 221 to 3 variables). Thus, the novel second-order factor solution is likely to be replicable and generalizable.

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Although the first-order EFA had a significantly less strong case-to-variable ratio, there are several reasons to infer that the identified factor solution is likely robust. Most importantly, the identified factor fit exactly with a priori theoretical prediction distinguishing between AS, distress tolerance, and discomfort intolerance; and the factor solution is consistent with existing measurement models of each construct (Schmidt et al., 2006; Simons & Gaher, 2005; Zinbarg et al., 1997). If novel firstorder factors were proposed or observed (i.e., inconsistent with prediction and/or inconsistent with measurement models), then a larger sample or multiple-sample EFAs may have been more important. In light of the reported findings, though, such additional study appears particularly appropriate for future research and replication. Finally, other latent structural study of AS has indicated that it may demonstrate a taxonic-dimensional structure (e.g., Bernstein et al., 2007). Additionally, not all facets of the AS construct appear to be good indicators of the latent construct (Zinbarg et al., 1999). For example, social concern items have historically had less robust associations with the global AS factor than other concerns and may not be meaningful indicators of the latent construct (Zinbarg et al., 1999; see also, Table 1). In the present investigation, AS was evaluated dimensionally and we did not explicitly measure its putative taxonic structure. However, it has been demonstrated that dimensional measures of the construct, such as ASI total score, reflect latent taxonic and continuous individual differences in the construct (Bernstein et al., 2007). Future investigations, methodologically (e.g., large sample size) and statistically designed to incorporate taxonic and dimensional structure could further evaluate the relations between AS taxonic-dimensionality and distress tolerance and their putative hierarchical structure. Furthermore, in light of taxometric findings of AS, and the observed hierarchical factor model of AS and distress tolerance, taxometric or related structural analyses might yield novel insights into the latent structure of the higher-order affect sensitivity and tolerance factor. Overall, the present investigation adds to the literature by providing a latent structural examination of AS within the context of distress tolerance and discomfort intolerance. Results suggest that each of the studied sensitivity and tolerance factors are distinct at a latent structural level. Yet, AS and distress tolerance may be related, lower-order factors of a higher-order variable. These findings help inform contemporary study of AS and other affect sensitivity and tolerance factors by suggesting

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