The sources of convergence between measures of apathy and depression

Journal of Affect&e Disorders, 28 (1993) 117- 124 0 1993 Elsevier Science Publishers B.V. All rights reserved

117 0165-0327/93/$06.00

JAD 00995

The sources of convergence between measures of apathy and depression Robert

S. Marin, Sekip Firinciogullari

and Ruth C. Biedrzycki

Department of Psychiatry, Uniwrsity of Pittsburgh School of Medicine, Pittsburgh, PA, USA (Received 4 September 1991) (Revision received 31 December 1992) (Accepted 19 January 1993)

Summary Apathy and depression are discriminable but related dimensions of behavior. The purpose of this study was to evaluate the source of the overlap between measures of apathy and depression. We evaluated the intercorrelations between the Apathy Evaluation Scale (AES) and the Hamilton Rating Scale for Depression (HamD) in 107 subjects, aged 53-85, who met research criteria for normal aging, left or right cerebral hemisphere stroke, probable Alzheimer’s disease, or major depression. We determined the correlation between the individual items on the HamD and the total scores on the AES and the HamD. The HamD items having the strongest correlations with AES total score were diminished work/interest, psychomotor retardation, anergy, and lack of insight. The correlation between AES and HamD total scores was nonsignificant when major depression subjects and these variables most closely related to apathy were excluded from consideration. These findings indicate that the convergence between HamD and AES is attributable to (i) a subset of HamD items which are consistent with the syndrome of apathy and (ii) the fact that major depression is associated with both apathy and depression. Clinical and research applications of these results are discussed.

Key words:

Apathy;

Alzheimer’s

disease;

Depression;

Introduction Differentiating clinical importance

apathy from depression is of because of the differences in

Correspondence to; Robert S. Marin, Western Institute and Clinic, 3811 O’Hara St., Pittsburgh, USA.

Psychiatric PA 15213,

Dementia;

Motivation;

Negative

symptom;

Stroke

the phenomenology, differential diagnosis, and management of these two syndromes (Marin, 1990). In recent work (Marin et al., 1991) we have presented evidence that apathy is a discriminable dimension of behavior representing lack of motivation, where motivation is defined as a superordinate concept referring to the psychological structure and the determinants of goal-directed behavior (Bindra, 1959; Madsen, 1973). For clini-

118

cal purposes apathy is usually viewed as a symptom of other more familiar syndromes, such as dementia or depression. However, in some instances apathy may present as a syndrome per se. Therefore, the syndrome of apathy has been conceptualized as a syndrome of diminished motivation in which the lack of motivation is not attributable to diminished level of consciousness, emotional distress, or cognitive deficits (Marin, 19911. To discriminate apathy from depression we followed (Marin et al., 1991) the guidelines of the multitrait multimethod matrix procedure (MTMM) (Campbell and Fisk, 1959). Clinician, informant, and self-rated versions of our apathy scale were compared to the Hamilton rating scale for depression, and to self and informant rated versions of the Zung depression scale. Although there was substantial discrimination between apathy and depression ratings, the correlation between them was nevertheless highly significant. For example, the discriminant validity coefficient (Pearson’s r) between the clinician rated version of the AES and the 17 item Hamilton Rating Scale (HamD) was 0.39 (P < 0.001). By contrast, the convergent validity coefficient (Pearson’s r) between clinician and self-rated versions of the AES was 0.72 (P < 0.001). Although these and other findings were supportive of the discriminant validity of the AES, the correlation between the AES and HamD raises the question of whether the AES is responding to depression, albeit with less sensitivity, than the HamD. Thus, the object of this study was to evaluate the source of the intercorrelation between the dimensions of apathy and depression as measured by the AES and HamD. Two sources of intercorrelation were considered: 1) Convergence attributable to features shared by the dimensions of apathy and depression: Given the differences between the syndromes of apathy and depression, we hypothesized that the correlation between the two scales was due to a subset of items on the HamD that is specifically related to the syndrome of apathy. Since apathy had been defined as lack of motivation, it was predicted that the intercorrelation between AES and HamD would be attributable to the HamD items .which seemed most closely related to moti-

vation, namely, the items for loss of work/interest, psychomotor retardation, lack of energy, and lack of insight. Lack of insight is relevant to lack of motivation since subjects who are unaware of goals or problems would not be expected to initiate behavior relevant to them. It was also predicted that the correlation would not be due to the HamD items that reflect dysphoria (depressed mood, guilt, suicidal ideation, anxiety, agitation) or other diagnosis specific features of depression (sleep disturbance, appetite and weight loss). 2) Covariance of apathy and depression in major depression: The occurrence of apathy in patients with depression has been well documented (Friedman et al., 1961; Grinker et al., 1961; Overall, 1963; Schulterbrandt et al., 1974). Therefore, it was hypothesized that exclusion of major depression patients would reduce the correlation of HamD items and total score with AES total scores. Methods Scale description

The development and validation of the AES have been previously described (Marin et al., 1991). In brief, self, informant (family or friend), and clinician rated versions of the AES were developed (AESS, AESI and AESC, respectively). The AESS and AESI are paper and pencil tests. The three versions each consist of the same 18 items, except for syntax modifications. The AES requires responses based on an assessment of the subject’s thoughts, emotions, and activities during the previous 4 weeks. Each item is rated on a 4 point Likert-type scale, with anchor points labeled as Not at all, Slightly, Somewhat, and A Lot. Items are recoded so that apathetic responses receive higher scores. Procedure

AESC and HamD ratings were carried out on the same occasion and by the same rater. The AESS was completed before the clinician rated scales were administered. We administered the 17 item version of the HamD, rating each item as it was administered and following the anchor points incorporated into the scale (Hamilton,

119

1967). There were two clinician raters (RSM and RCB). Informant scales were completed by a friend or family member acquainted with the subject’s daily activities. Reliability coefficients (internal consistency, test-retest reliability, and inter-rater reliability) for the three versions of the scale were between 0.76 and 0.94.

with failure to resume previous level of functioning or within 12 months of onset of the present illness; insulin-requiring diabetes mellitus; and hypertension inadequately controlled by medication. The inclusion criteria for the diagnostic groups were as follows: (1) Stroke: Single infarction of either the left or right cerebral hemisphere as indicated by history, neurological findings and head CT scan report. We included basal ganglia infarction (n = 1 each in left and right hemisphere stroke groups). Transient ischemic attacks were permitted unless laterality of the TIA indicated involvement of the hemisphere uninvolved by the stroke. Stroke subjects were evaluated 3 months to 3 years after their strokes. (2) Probable Alzheimer’s disease subjects met NINCDSADRDA criteria (McKhann et al., 1978) for probable Alzheimer’s disease. Probable Alzheimer’s disease subjects had Hachinski scale (Hachinski et al., 1975) ratings of < 5. (3) Major depression subjects met SADS RDC criteria (Spitzer et al., 1978) for major depressive disorder (unipolar, non-psychotic) and had Mini-mental state examination (MMS) (Folstein et al., 1975)

Subjects Subjects gave written informed consent following description of the procedure and were paid $10.00 per hour for their effort. Family members of probable Alzheimer’s disease subjects also gave written informed consent. Subjects were 55-85 years of age. They were all ambulatory and resided in dwellings which placed no restrictions on their daily activities. All subjects met the following exclusionary criteria: history of alcoholism; drug abuse; central nervous system disease other than stroke or probable Alzheimer’s disease; bipolar affective disorder; psychotic disorder; or systemic disease producing psychiatric symptoms; ECT within the previous 6 months; neuroleptic medication use within the previous 2 weeks; closed head injury

TABLE

1

Demographic

characteristics

No. Well Elderly Left Hemisphere Stroke Right Hemisphere Stroke Probable Alzheimer’s Disease Major Depression Total

Education

Income

(%‘c)*

(%) * *

M

F

Mean

STD

1

2

3

4

5

1

2

3

4

5

31 14 20 19 23

14 8 11 9 3

17 6 9 10 20

68.1 66.6 69.5 70.6 71.0

5.7 7.1 4.5 5.1 5.1

19 21 35 16 35

0 43 30 16 22

10 21 25 42 35

26 7 5 11 4

4.5 7 5 16 4

22 29 35 16 44

13 36 60 37 44

16 14 5 11 4

10 7 0 16 0

38 14 0 22 9

107

45

62

* Education (% of group in each category, 1 = < 12th grade completed. 2 = high school completed. 3 = some college or technical school. 4 = college graduate. 5 = received at least some post-graduate ** Income (% of group 1= 40.

Age

Sex

in each category,

rounded

to nearest

percent).

education. rounded

to nearest

percent;

annual

income;

in thousands

of dollars

per year)

120 TABLE

2

Clinical

characteristics HamD

NL LH RH AD MD

AESC

AESI

AESS

MMS

Mean

S.D.

Mean

S.D.

Mean

S.D.

Mean

S.D.

Mean

S.D.

4.1 6.5 8.8 5.1 19.9

4.0 5.8 4.9 4.9 5.9

26.0 30.9 34.3 43.1 38.7

5.6 10.5 8.7 10.1 9.4

26.3 28.1 35.4 48.5 41.7

7.5 6.9 10.9 9.8 15.0

28.1 31.1 31.7 35.2 38.5

6.4 8.0 6.6 8.5 10.2

29.1 25.5 27.1 19.8 27.9

1.1 4.3 2.3 6.0 1.9

HamD: F = 37.8, df = 4, 102, P < 0.0001. AESC: F = 14.2, df = 4, 102, P < 0.0001. AESI: F = 17.0, df = 4, 102, P < 0.0001. AESS: F = 6.4, df = 4, 102, P = 0.0001. MMS: F = 25.9, df = 4, 101, P < 0.0001. NL = Well Elderly; LH = Left hemisphere stroke; RH = Right hemisphere stroke; AD = probable Alzheimer’s major depression, HamD = Hamilton Rating Scale for Depression; AESC, AESI, AESS = Clinician, Informant, versions of Apathy Evaluation Scale, respectively; MMS = Mini-mental state examination (Folstein et al., 1975).

TABLE

disease; MD = and Self-Rated

3

Correlation

of HamD

items with total scores for total sample

Items

HAMD

AESC

AESI

AESS

Depression Guilt Suicide DFA MCA EMA Wrk/Int Retard. Agitation Anxiety Som An. Appetite Energy Libido Hypoch. Insight Weight

0.73 0.52 0.66 0.46 0.42 0.58 0.73 0.39 0.46 0.77 0.60 0.43 0.69 0.21 0.64 0.03 0.24

0.10 0.04 0.20 0.10 0.01 0.16 0.50 0.64 0.37 0.23 0.26 0.30 0.39 0.02 0.27 0.47 0.11

0.08 0.03 0.13 0.07 0.01 - 0.04 0.36 0.40 0.38 0.17 0.16 0.17 0.27 0.03 0.32 0.45 0.04

0.21 0.16 0.24 0.19 0.03 0.15 0.53 0.40 0.26 0.31 0.32 0.17 0.43 0.03 0.33 0.26 0.02

** ** ** ** ** ** ** ** ** ** ** ** ** **

** ** ** * * ** * **

** ** **

* ** **

** ** * * ** ** ** *

Legend: Table shows correlation (Spearman) of individual items of Hamilton rating scale for depression (HamD) with the total scores of the HamD and with the clinician, informant, and self-rated versions of the Apathy Evaluation Scale (AESC, AESI, and AESS) respectively. HamD totals for each correlation are calculated excluding the item in question. Abbrrciations for HamD items: Depres. = depressed mood; DFA = difficulty falling asleep; MCA = midcycle awakening; EMA = early morning awakening; Wrk/Int = diminished work and interest; Retard. = psychomotor retardation; Agitat. = agitation: Som An. = somatic anxiety; Hypoch. = hypochondriasis; Insight = loss of insight; Weight = weight loss. * 2-tailed * * 2.tailed

significance significance

level < 0.01. level < 0.001.

121

scores > 24. (4) Well elderly controls did not meet criteria for any DSM-III axis I diagnosis at the time of evaluation, and had a MMS of 26 or more. Results were separately analyzed for the clinician, informant, and self-rated versions of the AES. This was done in part because our original work showed some differences in the validity of the three versions of the scale. Analyzing the results separately therefore permitted us to further evaluate the validity of the three AES versions in terms of the questions addressed in this paper. This analysis is also of practical value to other users of the scale who may, for example (Starkstein, 1992) use only the informant version of the AES. To improve reliability, the AESC and HamD ratings reported here represent the averaged scores for raters 1 and 2, except for 17 subjects in whom only 1 set of ratings was obtained.

TABLE

Results Demographic and clinical characteristics of the subjects are summarized in Tables 1 and 2. Tables 3 and 4 present the correlations of individual HamD items with the total scores for HamD and the three versions of the AES (clinician, informant, and self-rated). Table 3 provides results for the entire sample. Table 4 provides results for the sample exclusive of major depression. Correlations of individual HamD items with HamD total scores are calculated after excluding the item in question from the HamD total score. As indicated in Table 3, the pattern of HamD item/total score correlations for the entire sample differs appreciably for the HamD and AES total scores. The item/HamD total score correlations are highly significant (P < 0.001) except for the HamD items for libido, insight and weight loss. By contrast, the items for diminished work/inter-

4

Correlation

of HamD

items with total scores

for sample

exclusive

of major depression

Items

HAMD

AESC

AESI

AESS

Depression Guilt Suicide DFA MCA EMA Wrk/Int Retard. Agitation Anxiety Som An. Appetite Energy Libido Hypoch. Insight Weight

0.49 0.46 0.49 0.31 0.36 0.52 0.57 0.44 0.30 0.58 0.43 0.36 0.63 0.39 0.51 0.11 0.14

-0.14 -0.12 0.10 - 0.02 -0.08 0.09 0.44 0.62 0.26 0.10 0.09 0.17 0.31 0.10 0.11 0.54 0.02

- 0.12 -0.14 0.06 0.04 - 0.003 -0.17 0.28 0.39 ** 0.29 * 0.01 - 0.01 0.04 0.20 0.09 0.07 0.54 ** -0.16

- 0.01 - 0.02 0.08 0.03 - 0.04 0.04 0.44 0.38 0.06 0.13 0.11 - 0.04 0.33 0.13 0.16 0.32 - 0.06

** ** ** * ** ** ** ** * ** ** ** ** ** **

** **

*

**

** **

*

*

Le~e&c Table shows correlation (Spearman) of individual items of Hamilton rating scale for depression (HamD) with the total scores of the HamD and with the clinician, informant, and self-rated versions of the Apathy Evaluation Scale (AESC, AESI, and AESS) respectively. HamD totals for each correlation are calculated excluding the item in question. Abbrekztions

for HamD

early morning An. = somatic * 2-tailed * * 2-tailed

items: Depres. = depressed mood; DFA = difficulty falling asleep; MCA = midcycle awakening; EMA = awakening; Wrk/Int = diminished work and interest; Retard. = psychomotor retardation. Agitat. = agitation; Som. anxiety; Hypoch. = hypochondriasis; Insight = loss of insight; Weight = weight loss.

significance significance

level < 0.01. level < 0.001.

122

and HamD scores, we recalculated the HamD/ AES total score correlations using a modified HamD total score. The modified HamD total score was calculated by excluding the subset of items hypothesized as most closely related to apathy, i.e., diminished work/interest, psychomotor retardation, lack of energy, and loss of insight. With or without major depression subjects (Table 5), the modified HamD score correlated well above 0.9 with the unmodified HamD, indicating that the removal of the items to construct the modified HamD score did not markedly alter its validity as a measure of depression. The changes in correlation coefficients associated with using the unmodified and modified HamD were tested (l-tailed) using the method of Cohen and Cohen (1975) for evaluating differences in correlations obtained from the same sample. Changes in correlation coefficient were tested separately for the total sample and for the sample exclusive of major depression. In both samples, the correlations of the modified HamD with AES scores (Table 5) were significantly lower than the respective correlations of HamD scores and AES scores. In fact, in the sample exclusive of major depression sub-

est, psychomotor retardation, agitation, lack of energy, hypochondriasis, and diminished insight show significant correlations with total scores for the three versions of the AES. In addition, there were significant correlations of the AES-C and AES-S with items for anxiety and appetite. To assess the contribution of major depression, these correlations were reevaluated when major depression subjects were excluded from consideration (Table 4). When major depression is excluded, all significant correlations with HamD total scores (again calculated excluding the item in question) remain so. In addition, the correlation of decreased libido with HamD total is now significant (r = 0.39, P < 0.001). The only items which now have significant correlations with the AES are the subset of items for work/interest, psychomotor retardation, energy, and insight. Responses for the AESI differ from the other two AES versions. For the AESI, the correlations with diminished work interest and lack of energy are not significant while the agitation correlation is significant. To evaluate the influence of apathy related HamD items on the correlations between AES TABLE

5

Correlations

between

total scales scores for apathy

and depression

*

Group

Scale

HamD

Mod HamD

AES-C

AES-I

All subjects (12 = 107)

HamD Mod HamD * * Excl items +

1.0 0.98 0.74

0.98 1.0 0.57

0.44 0.31 h,c 0.70

0.32 0.22 il.c 0.53

Subjects excluding major depression (n = 84)

HamD Mod HamD * * Excl items +

1.0 0.94 0.70

0.94 1.0 0.42

0.34 h 0.10 “.c 0.69

0.17 “ - 0.03 “.c 0.52

AES-S 0.50 0.42 ’ 0.59 0.24 “ 0.05 .‘.c 0.52

Table shows the intercorrelations (Pearson’s r) among the apathy scales, the HamD, the HamD exclusive of the items hypothesized a priori to reflect apathy (ModHamD), and a subscale defined by the subtotal among these four excluded items (ExclItm in Table). Correlations are shown for the entire sample and for the sample exclusive of subjects with major depression. are Pearson’s r, and all are significant at P < 0.001 (2-tailed) except: a Non-significant. h P < 0.01. rating scale excluding items for work/interest, psychomotor retardation, lack of energy. lack of insight. + Excl Items = total score for subscale formed by adding scores of items for dim. work/interest, psychomotor retardation, lack of in correlations (Cohen and Cohen, 1975) between HamD with AES and mod energy, lack of insight. ’ f-test for difference HamD with AES were all significant (P < 0.001, l-tailed). T-values were as follows:

* All correlations

** Mod HamD = Hamilton

AES-C AES-I

AES-s

Total sample

Sample

8.59 5.66 4.89

8.90 6.5 I 5.78

exclusive of major depression

123

jects, all correlations of the modHamD with AES scores were nonsignificant. We also evaluated the correlations of the excluded items with the depression and apathy scales. A subscale formed by summing scores of these four items (ExclItems in Table 5) correlated significantly lower with the ModHamD than with the HamD (t > 32, P < 0.001) in both samples. It also correlated modestly, though significantly, better with the AES-C than with the ModHamD (t = 2.67 and t = 2.86, P < 0.005, for total sample and sample exclusive of major depression, respectively). Conclusions These data support the discriminability of apathy and depression in a sample of elderly patients who are normal or who have diagnoses of hemispheric stroke, probable Alzheimer’s disease, and major depression. The data confirm our prediction that the correlation between AES and HamD total scores is primarily attributable to items which are conceptually related to apathy and, thus, nonspecifically related to the dimension of depression. Removal of major depression subjects highlights the fact that the overall correlation between depression and apathy in this sample is also due to the correlation of depression and apathy in major depression. When this subset of items and the major depression subjects are removed from consideration the correlation between AES and HamD total scores is nonsignificant. Since these data indicate that apathy may be uncorrelated with depression when individuals with major depression, and, presumably, other depressive disorders, are excluded, they also suggest that at least in some neurological disorders, apathy may occur in the absence of depression. Thus, our results support the suggestion (Marin, 1991) that there are some disorders in which apathy occurs as a syndrome per se and does not simply represent a symptom of some other more familiar behavioral syndrome such as anxiety or depression. Both apathy and depression syndromes may present diminished interest, psychomotor retardation, lack of energy, and lack of insight. Distinguishing the two syndromes is that

dysphoric symptoms, such as depressed mood, guilt or hopelessness, as well as vegetative symptoms, are at best weakly associated with apathy. In other words, lack of motivation occurs in both apathy and depression, but the syndrome of apathy denotes lack of motivation occurring in the absence of dysphoria or vegetative symptoms of depression. The association of apathy with psychomotor retardation, lack of energy, and diminished work/interest is not surprising. These features are consistent with the conventional definition of apathy as lack of interests and lack of emotion, and they can be identified in studies of such related concepts as emotional blunting (Abrams and Taylor, 19781, negative symptoms (Andreasen, 19821, and psychomotor retardation (Schulterbrandt et al., 1974; Widlocher and Ghozlan, 1989; Benson, 1990). The association of apathy with insight suggests that there may be diagnosis specific modifications of the clinical context in which lack of motivation occurs in neuropsychiatric disorders. Loss of insight is a characteristic of Alzheimer’s disease (Reisberg, 1983), frontal lobe syndromes (Stuss and Benson, 19841, and some patients with right hemisphere stroke (Heilman et al., 1985). In our sample, diminished insight was found in right hemisphere stroke, probable Alzheimer’s disease and major depression. Cognizance of the relationship between apathy and depression may avoid false positive diagnoses of depression. If patients are evaluated with the AES and the HamD, an apathy syndrome is suggested by apathy scores which are high relative to the depression score. Our experience suggests patients with apathy scores > 38 and HamD scores < 11 appear clinically apathetic. An elevated ratio of apathy/depression scores may also suggest apathy in patients with higher HamD scores, as well. The differentiation of apathy and depression syndromes also may be aided by considering the specific HamD items which are elevated. If elevated HamD scores are predominantly attributable to the items for diminished work/interest, retardation, anergy, and loss of insight it may be appropriate to consider the possibility that such patients are primarily apathetic rather than depressed. Causes of such apa-

124

thetic syndromes have been discussed elsewhere (Marin, 1991). A possibility more related to mood disorders is that in the elderly, and perhaps other groups, apathy may be the presenting feature of mood disorders. Such a picture of ‘depression without depression’ may account for some patients characterized in the past as masked depression (Blumenthal, 1980). A third consideration is that apathy may be a discriminable aspect of mood disorders having its own mechanism and treatment implications. For example, partial responders to anti-depressants who respond to psychostimulants may be patients who remain apathetic after their dysphoric and vegetative symptoms respond to anti-depressant treatment. Such patients would not be detected by HamD scores, but their apathy ratings and, as a result, psychosocial function would remain impaired (Fogel, B., 1992, personal communication). Finally, apathy in depressed patien;s may also be the result of treatment, since serotinergic reuptake inhibitors sometimes produce apathy (Hoehn-Saric et al., 1990). Each of these questions is of interest in its own right. Their investigation would clarify whether apathy and depression syndromes have different mechanisms or require different treatments in neuropsychiatric disorders. Acknowledgements Supported in (Academic Award 41930).

part by grants from NIA AGO02351 and NIMH (MH-

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