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TPQ in euthymic manic-depressive patients
J. psychiat. Res.. Vol. 30, No. 5. pp. 353 357. 1996 Copyrighl ~' 1996 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0022 3956/96 $15.00+,00
~-'~ Pergamon
PII: S0022-3956(96)00023-4
T P Q IN E U T H Y M I C
MANIC-DEPRESSIVE
PATIENTS
YAMIMA OSHER,* C. ROBERT CLONINGER-~ and R. H. BELMAKER* *Ministry of Health Mental Health Center, Ben Gurion University of the Negev, Beersheva, Israel: ?Department of Psychiatry, Washington University, School of Medicine, St Louis, U.S.A.
Summary--Researchers using various psychological measures and instruments have concluded that the personality of remitted bipolars and normal controls are essentially similar. We recently suggested that specific personality traits might be genetic markers for manic-depressive illness. The Tridimensional Personality Questionnaire (TPQ) is a personality questionnaire with heritable subscales and hypothesized anchoring in neurochemistry. We studied the personality of euthymic bipolar manic depressive patients using the TPQ. Subjects were volunteers from the out-patient Lithium Clinic. TPQs were individually administered to 50 euthymic bipolar patients. Persistence is significantly reduced, and harm avoidance and reward dependence significantly increased, compared with U.S. norms. These traits may be part of the genetic diathesis for manic-depressive illness. Copyright ~ 1996 Elsevier Science Ltd.
Introduction Researchers using various psychological measures and instruments have usually concluded that the respective personalities of remitted bipolars and normal controls are similar (Goodwin & Jamison, 1990). Manic-depressive illness seems orthogonal to personality type, and the subject has received little systematic attention in recent years. Wetzel et al. (1980) discussed the possibility that cyclothymic personality traits could be a subclinical expression of bipolar manic-depressive illness. Von Zerssen et al. (1994) compared personality'in unipolar vs bipolar patients but did not compare to controls. Akiskal (1995) used personality in affective patients to subtype affective disorder and to predict prognosis and drug response. Mandel et al. (1984) and Last et al. (1989) analysed Rorschach data using Exner's scoring system in 35 Israeli euthymic bipolar manic depressives vs U.S. norms and found some evidence of differences, especially poorer reality testing and afl'ective constriction in ~he euthymic bipolars. Genetic studies of twins and adoptees (Tellegen et al., 1988) suggest that many personality and temperament traits may be heritable to the same degree as schizophrenia and manicdepressive illness. Using various personality tests, traits such as extroversion introversion, dominance--submission, and passiveness activeness have a heritability of about 50% (Loehlin, 1992). Benjamin et al. (1993) reported preliminary data suggesting a linkage between the color-blindness locus and the Q-2 trait on the 16PF, usually called "group adherence" We recently suggested (Belmaker & Biederman. 1994) that specific personality Correspondence to: Ministry of Health Mental Heahh Center, Ben Gurion University of the Negev. Beersheva. Israel (Tel: +972 7 6401 602: Fax: +972 7 6401 621). 353
354
Y. Osher et al.
traits might be markers for manic-depressive illness not in the sense that all bipolar patients have the same personality, but that they may share a specific trait that represents the behavioral expression of a specific genetic neurochemical diathesis to manic-depressive illness. The Tridimensional Personality Questionnaire (TPQ) (Cloninger, 1987; Cloninger et al., 1991) is a personality questionnaire with heritable subscales (Heath et al., 1994) and hypothesized anchoring in neurochemistry. We, therefore, studied the personality ofeuthymic bipolar manic-depressive patients using the TPQ. Methods Subjects were volunteers from the out-patient Lithium Clinic serving a defined catchment area surrounding Beersheva, Israel. TPQs were individually administered to 50 euthymic bipolar patients (DSM-IV), representing all consenting patients with an educational level adequate to complete the questionnaire. Demographic data are summarized in Table 1. TPQ "questionnaire scores are only slightly influenced by socioeconomic factors" (Cloninger et al., 1991). In both our study sample and the U.S. norm sample (Cloninger et al., 1991), females slightly outnumber males; the study sample is slightly younger. Patients were assessed as euthymic by psychiatric interview by the treating psychiatrist (RHB) who had known the patients for a considerable time. The mean blood level of Li was 0.6 mM ( + 0.2 SD; range 0.3-1.3 mM); three patients were on other antibipolar treatments and one was receiving no treatment. For four patients, Li levels were unavailable during the month of TPQ testing. Subjects were instructed to fill out the questionnaire regarding themselves in their "balanced period, as now". Cloninger has shown that the TPQ measures four dimensions of temperament that are inherited independently of one another: harm avoidance (HA), novelty seeking (NS), reward dependence (RD), and persistence (P). RD is measured by the sum of subscales 1, 3, and 4 of the original RD scale, whereas P represents subscale 2 of the original RD scale (Cloninger et al., 1993, Cloninger et al., 1994). Results For analysis, two-tailed t-tests comparing sample- to population (U.S. norms) means were performed. Table 2 summarizes the results. Persistence (P) is significantly reduced in Table 1 Sample DemographicData
Age Education Married (%) Ashkenazi (%) Working (%)
Females N=28
Males N=22
36.1 _+12.5 Range 20~65 12.5_+2.3 years Range 8-20 46 39 75*
39.2_+12.2 Range 22 70 12.6_+2.7years Range 8-20 73 45 68
*Includes womenfunctioningas homemakers.
TPQ in Euthymic Manic-depressivePatients
355
Table 2 Major Scales o[" Tridimensional Personality Questionnaire in Bipolar Patients and U.S. Norms
NS (novelty seeking) HA (harm avoidance) RD (1, 3, 4) (reward dependence) P (RDJ (persistence)
Bipolars N= 50
U.S. norms+ N= 1019
x -+SD
x-+ SD
13.7_+3.9 14.8_+6.7" 14.7_+3.2" 3.5 _+1.5"*
13.0_+5.0 12.0_+5.9 13.4_+3.4 5.5 _+1.9
tFrom Cloninger et al. (1994). *p < 0.0! (t-test). **p<0.001 (t-test). the manic depressive sample (p<0.001). Within the bipolar sample, P does not differ significantly by sex (p = 0.21), ethnic group (Ashkenazi vs non-Ashkenazi) (p = 0.79), work status (working out of home, functioning homemakers and students vs those with major work disability) (p = 0.19), or type of last episode (depressive vs manic) (p = 0.29). Neither the age at onset (r = - 0 . 1 0 , p = 0.49), nor the number of previous hospitalizations (r = 0.2~4, p = 0.09) was correlated with persistence score, nor were blood levels of lithium correlat+d with persistence scores ( r = - 0 . 0 6 , p =0.71). P scores of the 14 subjects with the highest ki blood levels (above 0.80 m M ) compared to the P scores of the 10 subjects with the lowest Li blood levels (at or below 0.40 m M ) showed no significant difference (p = 0.29). EducatiOn does not correlate with P in our sample (r=0.10, p = 0 . 5 0 ) , nor does age ( r : - 0 . 1 ! 6 , p=0.25). Married bipolars had somewhat lower P scores than did unmarried bipol'Srs i x = 3 . 1 vs x =3.9, p=0.04). The euthymic bipolar patients have a statistically significant elevation of HA and RiD relative to U.S. normals ( p : 0.0 1), but the actual differences in mean scores are small (lass than 1/2 S D in both cases) and there is a very large overlap between groups. There is no significant difference in NS. Discussion Most personality traits of this euthymic bipolar manic-depressive group overlap U!S. norms. This confirms the concept that manic-depressive illness is not a specific outcome o f a defined overall personality constellation. However, persistence is significantly reduced iin this group of patients. Fifty per cent of the bipolar patients score below 1 S D below the normal mean. Low persistence was not found in depression (Kleifield et al., 1994), anxiety disorders (Fossey, 1995) or post-traumatic stress disorder (Kotler et al., in press): among anorectics, P is significantly elevated (Brewerton et al., 1993). This suggests that chro~ic illness is not enough to cause low P scores. Low persistence is characterized by a tendency to become discouraged and to give up when expectations are not quickly satisfied, rather than persevering despite frustration (Cloninger et al., 1993, 1994). Cloninger (1994) suggests that persistence might be measured by the partial reinforcement extinction effect (PREE) in which persistent individuals are
356
Y. Osher et al.
more resistant to extinction of previously intermittently rewarded behaviors than control individuals who have been continuously reinforced. In rodents, the integrity of the PREE is dependent on glutaminergic projections from the hippocampal subiculum to the nucleus accumbens (Tai et al., 1991). This connection may be considered to be a short circuit from the behavioral inhibition system to the behavioral activation system, thereby converting a conditioned signal of punishment into a conditioned signal of anticipated reward (Cloninger, 1994). Accordingly, if bipolar patients are low in persistence, it may be hypothesized that they are unusually susceptible to switches between behavioral activation and inhibition when positive reinforcement is intermittent. Ebstein et al. (1996) recently reported TPQ associations with D-4 receptor polymorphisms in a sample of Israeli normals, mostly students. The mean NS in that study was higher than U.S. norms and higher than the present sample of Israeli bipolars. This could be due to the over-representation of young students in the Ebstein et al. (1996) sample, since both youth and education increase NS. While increased NS is anecdotally and intuitively accepted as a characteristic of bipolar patients, systematic studies have not always documented this presumed trait (Goodwin & Jamison, 1990). It is possible that an increased NS in our bipolar sample is masked by lithium treatment. Strakowski et al. (1993) found that bipolars with increased NS at the time of discharge had a poorer prognosis at the 6-month follow-up, but they did not compare bipolar NS scores to controls, nor did they study a euthymic bipolar sample. The slight elevation of HA in our euthymic patients may reflect some residual depression, since depression can cause a significant elevation of HA (Joffee et al. 1993). Young et al. (1995) recently reported TPQ scores in bipolar and unipolar patients after recovery from an affective episode. HA was elevated compared to controls, much more than in our sample. NS was increased in bipolars only. RD was unchanged in the Young et al. (1995) study but was reported as the sum of RD 1, 2, 3 and 4. Thus, decreased persistence scores and increased RD 1, 3 and 4, as found in our study, could be consistent with the finding of Young et al. (1995) of unchanged RD t, 2, 3 and 4. P, unlike NS as discussed above, does not correlate with age or education, and thus our finding of low P is not likely to be due to inadequate matching on these factors. It should be noted that the present sample of euthymic bipolar patients was from a public hospital Lithium Clinic; it is possible that high persistence subjects seek private care and, therefore, we are currently conducting a replication study with privately treated bipolars. One must distinguish between a hypothesis that a personality constellation evolves into manic-depressive illness and the hypothesis that specific personality traits can serve as a phenotypic marker for the genetic-neurochemical diathesis to manic-depressive illness. The latter implies that bipolar illness can develop in numerous different personalities, but that bipolar patients usually share specific traits. It is this latter hypothesis for which we believe we may have found some support. References Akiskal, H. S. (1995). Toward a temperament-based approach to depression: implications for neurobiologic research. In G. Gressa, W. Fratta, L. Pani, & G. Serra (Eds), Depression and Mania: From Neurobiolo~fy to Treatment (pp. 99 112). New York: Raven Press.
TPQ in Euthymic Manic-depressive Patients
357
Belmaker, R. H., & Biederman, J. (1994). Genelic markers, temperament and psychopathology (editorial). Bioloyical Psychiatry, 36, 71 72. Benjamin, J., Press, J., Maoz, B., & Belmaker, R. 1t. (1993). Linkage of a normal personality trait to the colorblindness gene: preliminary evidence. Bioloyical Psychiatry, 34, 581 583. Brewerton, T., [land, L., & Bishop, E. (19933. The TPQ in eating disorder patients, htternationalJournal ~#Eatinc¢ Disorders, 14, 213- 218. Cloninger, C. R. (19873. A systematic method for clinical description and classitication of personality varianls. Archives o/'General Psychiatry, 44, 573 588. Cloninger, C. R. (1994). Temperament and personality. Current Opinion,s in Neurobiology, 4, 266 273. Cloninger, C. R.. Przybeck, T., & Svrakic, D. (1991). The tridimensional personality questionnaire: US normative data. Psychiatric Reports, 69, 1047---1057. Cloninger, C. R., Przybeck, T., Svrakic, D., & Wetzel, R. ( 19933. A psychobiological model of temperament and character. A rchives ql'General PsyehiattT, 50, 975 999 Cloninger, C. R., Przybeck T., Svrakic, D., & Wetzel, R. (19943. The Temperament attd Character bn,entory: A ,quide to its det~elopment and use (pp. 1 184). St Louis: Center for Psychobiology of Personality, Washington University. Ebstein, R. P., Novick, O., Umansky, R., Priel, B., Osher, Y., Blaine, D., Nemanov, L., Katz, M., Bennett, E.. & Belmaker, R. H. (1996). D4DR exon II1 polymorphism associated with personality variation in normals. Natlo'(, Genetics, 12, 78 80. Fossey, M. D. 119953. Assessment of treatment in male anxiety patients and normal male comparison subjects. Behavioral Pharmacoloqy 6, 39 (Abstract). Goodwin, F. K., & Jamison, K. R. (1990). Personality and interpersonal behavior. In Manic D~7)ressire llhu'.~s (pp. 281 317). Oxford: Oxford University Press. Heath, A., Cloninger, C. R., & Martin, N. (19943. Testing a model for the genetic structure of personality', a comparison of the personality systems of Cloninger and Eysenck. Journal ofPersonality and Social Ps'vc'holoqy, 66, 762 775. Jot'fee, R., Bagby, M., Levitt, A., Regan, J., & Parker, J. (19933. The TPQ in major depression. American Journal qlPsvchiatry, 150, 959 960. Kleifield, E., Sunday, S., Hurt, S., & Halmi, K. (1994). The effects of depression and treatment on the tridimensional personality questionnaire. Bioloyieal PsychiatiT, 36, 68 70. Kotler, M., Cohen, H., Matar, M., Amir, M.. Bleich, A., & Kaplan, Z. (in press). The TPQ in post-traum~tic stress disorder patients. Anxiety. Last, U., Mandel, B., Shapiro, E., & Belmaker, R. tt. (19893 In search of psychological markers of bipolar mai~icdepressive illness (BMDI): Some commonalties in psychological functioning between offspring of BMDIaffected parents and adult euthymic BMDI patients. Israeli Journal 01' P~w'hiatry and Related Science, 26, 75 84. Loehlin, J. (19923. Genes and environment h~personality development. Sage Publications.. Mandel, B., Last, U., Belmaker, R., & Rosenbaum, M. (19843. Rorschach markers in euthymic manic-depressive illness. Neuropsychobioloqy, 12, 96- 100. Strakowski, M., Stoll, A., Tohen, M., Faedda, G., & Goodwin. D. (1993). Fhe TPQ as a predictor of six-month outcome in tirst episode mania. Psychiatry Research, 48, 1 8. Tat, C. T.. Clark, A. J. M., Feldon, J., & Rawlins, J. N. P. (19913. Electrolytic lesions of the nucleus accumbens in rats which abolish the PREE enhance the locomotor response to amphetamine. Experimental Brain Research. 86, 333 340. Tellegen. A.. Lykken, D., Bouchard, T., Wilcox, K.. Segal, N., & Rich, S. ~1988). Personality similarity in twins reared apart and together. Journal of Personalio' and Social Psycholoyy, 54, 1031 1038. w)n Zerssen, D., Tauscher, R., & Possl, J. (19943. The relationship of premorbid personality to subtypes of an affective illness. Journal of Affbctive Disorders, 32, 61 72. Wetzel, R., Cloninger, C., Hong, B., & Reich, T. 11980). Personality as a ~ubclinical expression of the affective disorders. Comprehensive Psychiato', 21, 197 205. Young, T. L., Bagby, R. M., Cooke, R. G., Parker. J. D. A., Levitt. A. J., & Joffe, R. T. (1995). A comparisor~ of tridimensional personality questionnaire dimensions in bipolar disorder and unipolar depression. Psvchia!try Research, 58, 139 143.
~-'~ Pergamon
PII: S0022-3956(96)00023-4
T P Q IN E U T H Y M I C
MANIC-DEPRESSIVE
PATIENTS
YAMIMA OSHER,* C. ROBERT CLONINGER-~ and R. H. BELMAKER* *Ministry of Health Mental Health Center, Ben Gurion University of the Negev, Beersheva, Israel: ?Department of Psychiatry, Washington University, School of Medicine, St Louis, U.S.A.
Summary--Researchers using various psychological measures and instruments have concluded that the personality of remitted bipolars and normal controls are essentially similar. We recently suggested that specific personality traits might be genetic markers for manic-depressive illness. The Tridimensional Personality Questionnaire (TPQ) is a personality questionnaire with heritable subscales and hypothesized anchoring in neurochemistry. We studied the personality of euthymic bipolar manic depressive patients using the TPQ. Subjects were volunteers from the out-patient Lithium Clinic. TPQs were individually administered to 50 euthymic bipolar patients. Persistence is significantly reduced, and harm avoidance and reward dependence significantly increased, compared with U.S. norms. These traits may be part of the genetic diathesis for manic-depressive illness. Copyright ~ 1996 Elsevier Science Ltd.
Introduction Researchers using various psychological measures and instruments have usually concluded that the respective personalities of remitted bipolars and normal controls are similar (Goodwin & Jamison, 1990). Manic-depressive illness seems orthogonal to personality type, and the subject has received little systematic attention in recent years. Wetzel et al. (1980) discussed the possibility that cyclothymic personality traits could be a subclinical expression of bipolar manic-depressive illness. Von Zerssen et al. (1994) compared personality'in unipolar vs bipolar patients but did not compare to controls. Akiskal (1995) used personality in affective patients to subtype affective disorder and to predict prognosis and drug response. Mandel et al. (1984) and Last et al. (1989) analysed Rorschach data using Exner's scoring system in 35 Israeli euthymic bipolar manic depressives vs U.S. norms and found some evidence of differences, especially poorer reality testing and afl'ective constriction in ~he euthymic bipolars. Genetic studies of twins and adoptees (Tellegen et al., 1988) suggest that many personality and temperament traits may be heritable to the same degree as schizophrenia and manicdepressive illness. Using various personality tests, traits such as extroversion introversion, dominance--submission, and passiveness activeness have a heritability of about 50% (Loehlin, 1992). Benjamin et al. (1993) reported preliminary data suggesting a linkage between the color-blindness locus and the Q-2 trait on the 16PF, usually called "group adherence" We recently suggested (Belmaker & Biederman. 1994) that specific personality Correspondence to: Ministry of Health Mental Heahh Center, Ben Gurion University of the Negev. Beersheva. Israel (Tel: +972 7 6401 602: Fax: +972 7 6401 621). 353
354
Y. Osher et al.
traits might be markers for manic-depressive illness not in the sense that all bipolar patients have the same personality, but that they may share a specific trait that represents the behavioral expression of a specific genetic neurochemical diathesis to manic-depressive illness. The Tridimensional Personality Questionnaire (TPQ) (Cloninger, 1987; Cloninger et al., 1991) is a personality questionnaire with heritable subscales (Heath et al., 1994) and hypothesized anchoring in neurochemistry. We, therefore, studied the personality ofeuthymic bipolar manic-depressive patients using the TPQ. Methods Subjects were volunteers from the out-patient Lithium Clinic serving a defined catchment area surrounding Beersheva, Israel. TPQs were individually administered to 50 euthymic bipolar patients (DSM-IV), representing all consenting patients with an educational level adequate to complete the questionnaire. Demographic data are summarized in Table 1. TPQ "questionnaire scores are only slightly influenced by socioeconomic factors" (Cloninger et al., 1991). In both our study sample and the U.S. norm sample (Cloninger et al., 1991), females slightly outnumber males; the study sample is slightly younger. Patients were assessed as euthymic by psychiatric interview by the treating psychiatrist (RHB) who had known the patients for a considerable time. The mean blood level of Li was 0.6 mM ( + 0.2 SD; range 0.3-1.3 mM); three patients were on other antibipolar treatments and one was receiving no treatment. For four patients, Li levels were unavailable during the month of TPQ testing. Subjects were instructed to fill out the questionnaire regarding themselves in their "balanced period, as now". Cloninger has shown that the TPQ measures four dimensions of temperament that are inherited independently of one another: harm avoidance (HA), novelty seeking (NS), reward dependence (RD), and persistence (P). RD is measured by the sum of subscales 1, 3, and 4 of the original RD scale, whereas P represents subscale 2 of the original RD scale (Cloninger et al., 1993, Cloninger et al., 1994). Results For analysis, two-tailed t-tests comparing sample- to population (U.S. norms) means were performed. Table 2 summarizes the results. Persistence (P) is significantly reduced in Table 1 Sample DemographicData
Age Education Married (%) Ashkenazi (%) Working (%)
Females N=28
Males N=22
36.1 _+12.5 Range 20~65 12.5_+2.3 years Range 8-20 46 39 75*
39.2_+12.2 Range 22 70 12.6_+2.7years Range 8-20 73 45 68
*Includes womenfunctioningas homemakers.
TPQ in Euthymic Manic-depressivePatients
355
Table 2 Major Scales o[" Tridimensional Personality Questionnaire in Bipolar Patients and U.S. Norms
NS (novelty seeking) HA (harm avoidance) RD (1, 3, 4) (reward dependence) P (RDJ (persistence)
Bipolars N= 50
U.S. norms+ N= 1019
x -+SD
x-+ SD
13.7_+3.9 14.8_+6.7" 14.7_+3.2" 3.5 _+1.5"*
13.0_+5.0 12.0_+5.9 13.4_+3.4 5.5 _+1.9
tFrom Cloninger et al. (1994). *p < 0.0! (t-test). **p<0.001 (t-test). the manic depressive sample (p<0.001). Within the bipolar sample, P does not differ significantly by sex (p = 0.21), ethnic group (Ashkenazi vs non-Ashkenazi) (p = 0.79), work status (working out of home, functioning homemakers and students vs those with major work disability) (p = 0.19), or type of last episode (depressive vs manic) (p = 0.29). Neither the age at onset (r = - 0 . 1 0 , p = 0.49), nor the number of previous hospitalizations (r = 0.2~4, p = 0.09) was correlated with persistence score, nor were blood levels of lithium correlat+d with persistence scores ( r = - 0 . 0 6 , p =0.71). P scores of the 14 subjects with the highest ki blood levels (above 0.80 m M ) compared to the P scores of the 10 subjects with the lowest Li blood levels (at or below 0.40 m M ) showed no significant difference (p = 0.29). EducatiOn does not correlate with P in our sample (r=0.10, p = 0 . 5 0 ) , nor does age ( r : - 0 . 1 ! 6 , p=0.25). Married bipolars had somewhat lower P scores than did unmarried bipol'Srs i x = 3 . 1 vs x =3.9, p=0.04). The euthymic bipolar patients have a statistically significant elevation of HA and RiD relative to U.S. normals ( p : 0.0 1), but the actual differences in mean scores are small (lass than 1/2 S D in both cases) and there is a very large overlap between groups. There is no significant difference in NS. Discussion Most personality traits of this euthymic bipolar manic-depressive group overlap U!S. norms. This confirms the concept that manic-depressive illness is not a specific outcome o f a defined overall personality constellation. However, persistence is significantly reduced iin this group of patients. Fifty per cent of the bipolar patients score below 1 S D below the normal mean. Low persistence was not found in depression (Kleifield et al., 1994), anxiety disorders (Fossey, 1995) or post-traumatic stress disorder (Kotler et al., in press): among anorectics, P is significantly elevated (Brewerton et al., 1993). This suggests that chro~ic illness is not enough to cause low P scores. Low persistence is characterized by a tendency to become discouraged and to give up when expectations are not quickly satisfied, rather than persevering despite frustration (Cloninger et al., 1993, 1994). Cloninger (1994) suggests that persistence might be measured by the partial reinforcement extinction effect (PREE) in which persistent individuals are
356
Y. Osher et al.
more resistant to extinction of previously intermittently rewarded behaviors than control individuals who have been continuously reinforced. In rodents, the integrity of the PREE is dependent on glutaminergic projections from the hippocampal subiculum to the nucleus accumbens (Tai et al., 1991). This connection may be considered to be a short circuit from the behavioral inhibition system to the behavioral activation system, thereby converting a conditioned signal of punishment into a conditioned signal of anticipated reward (Cloninger, 1994). Accordingly, if bipolar patients are low in persistence, it may be hypothesized that they are unusually susceptible to switches between behavioral activation and inhibition when positive reinforcement is intermittent. Ebstein et al. (1996) recently reported TPQ associations with D-4 receptor polymorphisms in a sample of Israeli normals, mostly students. The mean NS in that study was higher than U.S. norms and higher than the present sample of Israeli bipolars. This could be due to the over-representation of young students in the Ebstein et al. (1996) sample, since both youth and education increase NS. While increased NS is anecdotally and intuitively accepted as a characteristic of bipolar patients, systematic studies have not always documented this presumed trait (Goodwin & Jamison, 1990). It is possible that an increased NS in our bipolar sample is masked by lithium treatment. Strakowski et al. (1993) found that bipolars with increased NS at the time of discharge had a poorer prognosis at the 6-month follow-up, but they did not compare bipolar NS scores to controls, nor did they study a euthymic bipolar sample. The slight elevation of HA in our euthymic patients may reflect some residual depression, since depression can cause a significant elevation of HA (Joffee et al. 1993). Young et al. (1995) recently reported TPQ scores in bipolar and unipolar patients after recovery from an affective episode. HA was elevated compared to controls, much more than in our sample. NS was increased in bipolars only. RD was unchanged in the Young et al. (1995) study but was reported as the sum of RD 1, 2, 3 and 4. Thus, decreased persistence scores and increased RD 1, 3 and 4, as found in our study, could be consistent with the finding of Young et al. (1995) of unchanged RD t, 2, 3 and 4. P, unlike NS as discussed above, does not correlate with age or education, and thus our finding of low P is not likely to be due to inadequate matching on these factors. It should be noted that the present sample of euthymic bipolar patients was from a public hospital Lithium Clinic; it is possible that high persistence subjects seek private care and, therefore, we are currently conducting a replication study with privately treated bipolars. One must distinguish between a hypothesis that a personality constellation evolves into manic-depressive illness and the hypothesis that specific personality traits can serve as a phenotypic marker for the genetic-neurochemical diathesis to manic-depressive illness. The latter implies that bipolar illness can develop in numerous different personalities, but that bipolar patients usually share specific traits. It is this latter hypothesis for which we believe we may have found some support. References Akiskal, H. S. (1995). Toward a temperament-based approach to depression: implications for neurobiologic research. In G. Gressa, W. Fratta, L. Pani, & G. Serra (Eds), Depression and Mania: From Neurobiolo~fy to Treatment (pp. 99 112). New York: Raven Press.
TPQ in Euthymic Manic-depressive Patients
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