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Bipolar disorder
Journal of Affective Disorders 82 (2004) 131 – 134 www.elsevier.com/locate/jad
Brief report
Bipolar disorder I. Temperament and character Christer Engstro¨m a, Sven Bra¨ndstro¨m a, So¨ren Sigvardsson b, Robert Cloninger c, Per-Olof Nylander a,d,* a
Department of Neuroscience and Locomotion, University of Linko¨ping, Sweden b Department of Social Medicine, University of Umea˚, Sweden c Department of Psychiatry, School of Medicine, Washington University, St Louis, USA d Department of Psychiatry, 393 59 Kalmar, Sweden Received 25 February 2002; received in revised form 18 September 2003; accepted 22 September 2003
Abstract Background: The nature of the relationship between personality and bipolar affective disorders is an important but unanswered question. Methods: We have studied personality in bipolar patients by using the Temperament and Character Inventory (TCI). TCI were administered to 100 euthymic bipolar patients and 100 controls from the normal population. Results: Bipolar patients were significantly higher in harm avoidance (HA) and lower in reward dependence (RD), self-directedness (SD), and cooperativeness (CO) than controls. Bipolar patients are more fatigable, less sentimental, more independent, less purposeful, less resourceful, less empathic, less helpful, less pure-hearted, and have less impulse control than controls. Bipolar II patients are more impulsive, more fatigable, less resourceful, and have less impulse control than bipolar I patients. Limitations: Our results are limited to euthymic bipolar patients and cannot be generalized to affective disorders. Conclusions: Even when clinically euthymic on lithium maintenance, bipolar patients continue to have a characteristic cognitive deficit. This is in agreement with cognitive theories about cognitive deficits in depression that are regarded as important vulnerability factors in mood disorders. D 2003 Elsevier B.V. All rights reserved. Keywords: Personality; Temperament; Character; Bipolar
1. Introduction The nature of the relationship between personality and bipolar disorder is an important but unanswered question. Personality may predispose to bipolar disorder or may modify the natural history of illness and * Corresponding author. Department of Psychiatry, 393 59 Kalmar, Sweden. Tel.: +46-480-81000; fax: +46-480-448991. E-mail address: [email protected] (P.O. Nylander). 0165-0327/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2003.09.004
response to treatment. Alternatively, personality traits may be subclinical expressions of the underlying vulnerability or may be altered by current or past mood state. Others have concluded that the respective personalities of remitted bipolar patients and normal controls are similar (Goodwin and Jamison, 1990; Cloninger, 1999; Cloninger et al., 1998). Tridimensional Personality Questionnaire (TPQ) has been used in several studies of personality in bipolar affective disorder. High harm avoidance (HA)
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C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
and high novelty seeking (NS) has been found in patients with mixed form of the disease (Strakowski et al., 1992). They also found no difference in personality between manic patients and controls. Strakowski et al. (1993) found that high NS predicted poorer prognoses in patients with mania. A study (Young et al., 1995) of bipolar and unipolar patients after recovery from an affective episode found elevated HA, increased NS and unchanged reward dependence (RD). Osher et al. (1996) reported low persistence (PS), high HA and high RD in a study of euthymic bipolar patients. Another study (Osher et al., 1999) found low NS and low PS in euthymic bipolar patients. There is much information available on temperament factors in bipolar disorder, but little information on character factors. Our hypothesis is that personality is an important factor with influence on the clinical expression of bipolar disorder. Therefore, the aim of this study is to examine both the temperament and character of euthymic bipolar patients using the Temperament and Character Inventory (TCI).
2. Material and methods Bipolar patients (40 females and 60 males; age 55.8 F 14.3 years) were recruited from the lithium dispensaries of Umea˚, Sundsvall and Ha¨rno¨sand Hospitals in Sweden. One hundred controls matched for age (54.8 F 14.7 years) and gender were chosen from a sample consisting of randomly recruited volunteers from the normal population (Richter et al., 1999). No patient met the criteria for rapid cyclers (Stancer et al., 1970). All cases have been continuously followed from age of onset to death or to the time of investigation. Patients were interviewed by PSE-10 (Wing et al., 1990) and data checked by OPCRIT (Farmer et al., 1992). Diagnosis and an affective episode were established or defined according to DSM-IV (American Psychiatric Association, 1987). Informed consent was obtained from all participants and the Ethical Committee approved the study. Lithium treatment was used alone, i.e. not in combination with any other psychotropic drug, except for hypnotics, anxiolytics, and acute recurrences after which additional medication again was discontinued. Mean serum lithium was 0.60 F 0.11 mmol/l and mean length of treatment was 12.8 F 7.9 years.
TCI was used for measuring personality (Cloninger et al., 1994). The temperament dimensions are novelty seeking (NS), harm avoidance (HA), reward dependence (RD), and persistence (PS). The character dimensions are self-directedness (SD), cooperativeness (CO), and self-transcendence (ST). All patients were at time of administration of TCI outpatients, in a stable phase, and clinically euthymic. Mann – Whitney rank sum test for independent samples was used for comparing bipolar groups. Ttest for dependent samples were used for comparing bipolar groups with controls. Two-tailed p-values were used for all tests. Effect size was used to compare differences (Cohen et al., 1988). Because the scale scores within each TCI dimension are correlated and thus not independent measures, we did not make a Bonferoni or other correction for multiple comparisons.
3. Results Overall the differences in personality between bipolar groups and controls (Table 1) were weak in effect size except for CO in bipolar II, which was moderate. The total bipolar group was higher in HA ( p = 0.020) and lower in RD ( p = 0.012), SD ( p = 0.027) and CO ( p = 0.003) compared to controls. Bipolar I patients were lower in RD ( p = 0.040) and CO ( p = 0.020) while bipolar II patients were lower in CO ( p = 0.042). The bipolar groups were compared to controls on the individual subscales for temperament and character. The total group was higher in rapid fatigability (HA4; p < 0.001) and lower in sentimentality (RD1; p = 0.035), dependence (RD4; p = 0.043) resourcefulness (SD3; p = 0.001), impulse control (SD5; p = 0.045), empathy (CO2; p = 0.003), helpfulness (CO3; p = 0.004), and pure hearted (CO5; p = 0.020). Effect sizes were weak except for rapid fatigability (moderate). Both bipolar I ( p = 0.001) and II ( p = 0.003) patients were higher in rapid fatigability compared to controls, and the differences were moderate and strong. Bipolar I patients were lower in resourcefulness ( p = 0.008), empathy ( p = 0.010), and helpfulness ( p = 0.009). Effect size was moderate in resourcefulness but weak in the others. Further, bipolar II patients
C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
133
Table 1 Higher order dimensions of temperament and character in bipolar, controls and effect size of bipolar patient Bipolar (I and II) (N = 100)
Bipolar I (N = 75)
Mean
Bipolar II (N = 25)
Controls (N = 100)
Bipolar (I and II) vs. controls
Bipolar I vs. controls
Bipolar II vs. controls
Bipolar I vs. bipolar II
d/s
d/s
d/s
S.D.
Mean S.D. Mean S.D. Mean S.D. d/s
P
Temperament NS 18.1 HA 16.8 RD 13.9 PS 3.4
P
5.5 7.1 3.5 1.9
17.8 16.1 13.8 3.6
5.0 7.1 3.4 1.9
19.0 18.8 14.0 2.8
6.9 7.1 4.0 1.7
18.1 14.5 15.1 3.7
5.3 6.2 3.6 1.7
0.00 0.34 0.34 0.19
ns 0.020 0.012 ns
0.14 0.30 0.34 0.22
Character SD 31.1 CO 32.1 ST 11.9
6.7 4.8 6.5
31.7 32.3 12.0
6.7 5.0 6.2
29.4 31.7 11.8
6.6 4.2 7.4
33.1 34.2 12.8
6.4 4.2 5.9
0.29 0.45 0.14
0.044 0.003 ns
0.22 ns 0.40 0.020 0.01 ns
ns ns 0.040 ns
0.38 0.48 0.37 0.11
P ns ns ns ns
0.50 ns 0.67 0.042 0.58 ns
P
0.20 0.39 0.07 0.40
ns ns ns ns
0.35 0.12 0.03
ns ns ns
NS = novelty seeking; HA = harm avoidance; RD = reward dependence; PS = persistence; SD = self-directedness; CO = cooperativeness; ST = self-transcendence. d/s = effect size; ns = nonsignificant.
were lower in purposeful (SD2; p = 0.018), impulse control ( p = 0.034), and pure hearted ( p = 0.028). Overall the differences were moderate. Bipolar I patients were lower in impulsivity (NS2; p = 0.044) and rapid fatigability ( p = 0.001), while they were higher in resourcefulness ( p = 0.048) and impulse control ( p = 0.028) compared to bipolar II patients. The differences were strong in rapid fatigability, respectively, moderate in the others.
4. Discussion Even when clinically euthymic, bipolar patients continue to describe themselves as more fatigable, less sentimental, more independent, less purposeful, less resourceful, less empathic, less helpful, less purehearted, and have less impulse control than controls. Since all subjects had previously been ill, we cannot determine whether these reflect premorbid personality traits rather than sequelae of previous illness. Bipolar I and II patients are similar in personality on the higher dimensions of temperament and character, but on lower dimensions bipolar II patients are more impulsive, fatigable, less resourceful, and have less impulse control. Lithium has been found to decrease neuroticism, and altered habitual patterns of personality in bipolar patients. Our study and other studies (Strakowski et al., 1992; Young et al., 1995; Osher et al., 1996, 1999)
of bipolar patients with and without lithium treatment have found similar results in temperament. Our results can therefore not be explained by a side effect from lithium treatment. These results indicate that bipolar patients who are apparently euthymic on lithium maintenance continue to have a characteristic cognitive deficit. These findings are consistent with cognitive theories about cognitive deficits in depression in which beliefs that ‘‘I am helpless’’ and ‘‘I am unlovable’’ are regarded as important vulnerability factors in mood disorders (Beck, 1999).
Acknowledgements We thank Barbro Nordqvist-Karlsson for his help in collecting data. References American Psychiatric Association, 1987. Diagnostic and Statistical Manual of Mental Disorders, 3rd ed. rev. American Psychiatric Press, Washington, DC. Beck, A.T., 1999. Cognitive aspects of personality disorders and their relation to syndromal disorders: a psychoevolutionary approach. In: Cloninger, C.R. (Ed.), Personality and Psychopathology. American Psychiatric Press, Washington, D.C, pp. 411 – 430. Cloninger, C.R., 1999. Personality and Psychopathology. American Psychiatric Press, Washington, D.C. Cloninger, C.R., Przybeck, T.R., Svrakic, D.M., Wetzel, R.D.,
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C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
1994. The Temperament and Character Inventory (TCI): A Guide to its Development and Use. Center for Psychobiology of Personality, Washington University, St. Louis, MO. Cloninger, C.R., Bayon, C., Svrakic, D.M., 1998. Measurement of temperament and character in mood disorders: a model of fundamental states as personality types. J. Affect. Disord. 51 (1), 21 – 32. Cohen, J., 1988. Statistical Powers Analysis for the Behavioral Sciences, 2nd ed. Lawrence Earlbaum Associates, Hillsdale, NJ. Farmer, A.E., Wessely, S., Castle, D., McGuffin, P., 1992. Methodological issues in using a polydiagnostic approach to define psychotic illness. Br. J. Psychiatry 161, 824 – 830. Goodwin, F.K., Jamison, K., 1990. Personality and interpersonal behaviour. In: Goodwin, F.K., Jamison, K. (Eds.), Manic Depressive Illness. Oxford Univ. Press, Oxford, pp. 281 – 317. Osher, Y., Cloninger, C.R., Belmaker, R.H., 1996. TPQ in euthymic manic depressive patients. J. Psychol. Res. 30 (5), 353 – 357. Osher, Y., Lefkifer, E., Kotler, M., 1999. Low persistence in euthymic manic-depressive patients: a replication. J. Affect. Disord. 53, 87 – 90. Richter, J., Bra¨ndstro¨m, S., Przybeck, T., 1999. Assessing perso-
nality: the temperament and character in a cross-cultural comparison between Germany, Sweden and the USA. Psychol. Rep. 84, 1315 – 1330. Stancer, H.C., Furlong, F.W., Godse, D.D., 1970. A longitudinal investigation of lithium as a prophylactic agent for recurrent depressions. Can. Psychiatr. Assoc. J. 15, 29 – 40. Strakowski, S.M., Faedda, G.I., Thoen, M., Goodwin, D.C., Stoll, A.L., 1992. Possible affective-state dependence of the tridimensional personality questionnaire. Psychol. Res. 41 (3), 215 – 226. Strakowski, S.M., Stoll, A.L., Thoen, M., Faedda, G.L., Goodwin, D.C., 1993. The tridimensional personality questionnaire a predictor of six month outcome in first episode mania. Psychol. Res. 48, 1 – 8. Wing, J.K., Babor, T., Brugha, T., Burke, J., Cooper, J.E., Giel, R., Jablenski, A., Regier, D., Sartorius, N., 1990. SCAN: schedules for clinical assessment in neuropsychiatry. Arch. Gen. Psychiatry 47, 589 – 593. Young, T.L., Bagby, R.M., Cooke, R.G., Parke, J.D.A., Levitt, A.J., Joffe, R.T., 1995. A comparison of tridimensional personality questionnaire dimensions in bipolar disorder and unipolar depression. Psychol. Res. 58, 139 – 143.
Brief report
Bipolar disorder I. Temperament and character Christer Engstro¨m a, Sven Bra¨ndstro¨m a, So¨ren Sigvardsson b, Robert Cloninger c, Per-Olof Nylander a,d,* a
Department of Neuroscience and Locomotion, University of Linko¨ping, Sweden b Department of Social Medicine, University of Umea˚, Sweden c Department of Psychiatry, School of Medicine, Washington University, St Louis, USA d Department of Psychiatry, 393 59 Kalmar, Sweden Received 25 February 2002; received in revised form 18 September 2003; accepted 22 September 2003
Abstract Background: The nature of the relationship between personality and bipolar affective disorders is an important but unanswered question. Methods: We have studied personality in bipolar patients by using the Temperament and Character Inventory (TCI). TCI were administered to 100 euthymic bipolar patients and 100 controls from the normal population. Results: Bipolar patients were significantly higher in harm avoidance (HA) and lower in reward dependence (RD), self-directedness (SD), and cooperativeness (CO) than controls. Bipolar patients are more fatigable, less sentimental, more independent, less purposeful, less resourceful, less empathic, less helpful, less pure-hearted, and have less impulse control than controls. Bipolar II patients are more impulsive, more fatigable, less resourceful, and have less impulse control than bipolar I patients. Limitations: Our results are limited to euthymic bipolar patients and cannot be generalized to affective disorders. Conclusions: Even when clinically euthymic on lithium maintenance, bipolar patients continue to have a characteristic cognitive deficit. This is in agreement with cognitive theories about cognitive deficits in depression that are regarded as important vulnerability factors in mood disorders. D 2003 Elsevier B.V. All rights reserved. Keywords: Personality; Temperament; Character; Bipolar
1. Introduction The nature of the relationship between personality and bipolar disorder is an important but unanswered question. Personality may predispose to bipolar disorder or may modify the natural history of illness and * Corresponding author. Department of Psychiatry, 393 59 Kalmar, Sweden. Tel.: +46-480-81000; fax: +46-480-448991. E-mail address: [email protected] (P.O. Nylander). 0165-0327/$ - see front matter D 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2003.09.004
response to treatment. Alternatively, personality traits may be subclinical expressions of the underlying vulnerability or may be altered by current or past mood state. Others have concluded that the respective personalities of remitted bipolar patients and normal controls are similar (Goodwin and Jamison, 1990; Cloninger, 1999; Cloninger et al., 1998). Tridimensional Personality Questionnaire (TPQ) has been used in several studies of personality in bipolar affective disorder. High harm avoidance (HA)
132
C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
and high novelty seeking (NS) has been found in patients with mixed form of the disease (Strakowski et al., 1992). They also found no difference in personality between manic patients and controls. Strakowski et al. (1993) found that high NS predicted poorer prognoses in patients with mania. A study (Young et al., 1995) of bipolar and unipolar patients after recovery from an affective episode found elevated HA, increased NS and unchanged reward dependence (RD). Osher et al. (1996) reported low persistence (PS), high HA and high RD in a study of euthymic bipolar patients. Another study (Osher et al., 1999) found low NS and low PS in euthymic bipolar patients. There is much information available on temperament factors in bipolar disorder, but little information on character factors. Our hypothesis is that personality is an important factor with influence on the clinical expression of bipolar disorder. Therefore, the aim of this study is to examine both the temperament and character of euthymic bipolar patients using the Temperament and Character Inventory (TCI).
2. Material and methods Bipolar patients (40 females and 60 males; age 55.8 F 14.3 years) were recruited from the lithium dispensaries of Umea˚, Sundsvall and Ha¨rno¨sand Hospitals in Sweden. One hundred controls matched for age (54.8 F 14.7 years) and gender were chosen from a sample consisting of randomly recruited volunteers from the normal population (Richter et al., 1999). No patient met the criteria for rapid cyclers (Stancer et al., 1970). All cases have been continuously followed from age of onset to death or to the time of investigation. Patients were interviewed by PSE-10 (Wing et al., 1990) and data checked by OPCRIT (Farmer et al., 1992). Diagnosis and an affective episode were established or defined according to DSM-IV (American Psychiatric Association, 1987). Informed consent was obtained from all participants and the Ethical Committee approved the study. Lithium treatment was used alone, i.e. not in combination with any other psychotropic drug, except for hypnotics, anxiolytics, and acute recurrences after which additional medication again was discontinued. Mean serum lithium was 0.60 F 0.11 mmol/l and mean length of treatment was 12.8 F 7.9 years.
TCI was used for measuring personality (Cloninger et al., 1994). The temperament dimensions are novelty seeking (NS), harm avoidance (HA), reward dependence (RD), and persistence (PS). The character dimensions are self-directedness (SD), cooperativeness (CO), and self-transcendence (ST). All patients were at time of administration of TCI outpatients, in a stable phase, and clinically euthymic. Mann – Whitney rank sum test for independent samples was used for comparing bipolar groups. Ttest for dependent samples were used for comparing bipolar groups with controls. Two-tailed p-values were used for all tests. Effect size was used to compare differences (Cohen et al., 1988). Because the scale scores within each TCI dimension are correlated and thus not independent measures, we did not make a Bonferoni or other correction for multiple comparisons.
3. Results Overall the differences in personality between bipolar groups and controls (Table 1) were weak in effect size except for CO in bipolar II, which was moderate. The total bipolar group was higher in HA ( p = 0.020) and lower in RD ( p = 0.012), SD ( p = 0.027) and CO ( p = 0.003) compared to controls. Bipolar I patients were lower in RD ( p = 0.040) and CO ( p = 0.020) while bipolar II patients were lower in CO ( p = 0.042). The bipolar groups were compared to controls on the individual subscales for temperament and character. The total group was higher in rapid fatigability (HA4; p < 0.001) and lower in sentimentality (RD1; p = 0.035), dependence (RD4; p = 0.043) resourcefulness (SD3; p = 0.001), impulse control (SD5; p = 0.045), empathy (CO2; p = 0.003), helpfulness (CO3; p = 0.004), and pure hearted (CO5; p = 0.020). Effect sizes were weak except for rapid fatigability (moderate). Both bipolar I ( p = 0.001) and II ( p = 0.003) patients were higher in rapid fatigability compared to controls, and the differences were moderate and strong. Bipolar I patients were lower in resourcefulness ( p = 0.008), empathy ( p = 0.010), and helpfulness ( p = 0.009). Effect size was moderate in resourcefulness but weak in the others. Further, bipolar II patients
C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
133
Table 1 Higher order dimensions of temperament and character in bipolar, controls and effect size of bipolar patient Bipolar (I and II) (N = 100)
Bipolar I (N = 75)
Mean
Bipolar II (N = 25)
Controls (N = 100)
Bipolar (I and II) vs. controls
Bipolar I vs. controls
Bipolar II vs. controls
Bipolar I vs. bipolar II
d/s
d/s
d/s
S.D.
Mean S.D. Mean S.D. Mean S.D. d/s
P
Temperament NS 18.1 HA 16.8 RD 13.9 PS 3.4
P
5.5 7.1 3.5 1.9
17.8 16.1 13.8 3.6
5.0 7.1 3.4 1.9
19.0 18.8 14.0 2.8
6.9 7.1 4.0 1.7
18.1 14.5 15.1 3.7
5.3 6.2 3.6 1.7
0.00 0.34 0.34 0.19
ns 0.020 0.012 ns
0.14 0.30 0.34 0.22
Character SD 31.1 CO 32.1 ST 11.9
6.7 4.8 6.5
31.7 32.3 12.0
6.7 5.0 6.2
29.4 31.7 11.8
6.6 4.2 7.4
33.1 34.2 12.8
6.4 4.2 5.9
0.29 0.45 0.14
0.044 0.003 ns
0.22 ns 0.40 0.020 0.01 ns
ns ns 0.040 ns
0.38 0.48 0.37 0.11
P ns ns ns ns
0.50 ns 0.67 0.042 0.58 ns
P
0.20 0.39 0.07 0.40
ns ns ns ns
0.35 0.12 0.03
ns ns ns
NS = novelty seeking; HA = harm avoidance; RD = reward dependence; PS = persistence; SD = self-directedness; CO = cooperativeness; ST = self-transcendence. d/s = effect size; ns = nonsignificant.
were lower in purposeful (SD2; p = 0.018), impulse control ( p = 0.034), and pure hearted ( p = 0.028). Overall the differences were moderate. Bipolar I patients were lower in impulsivity (NS2; p = 0.044) and rapid fatigability ( p = 0.001), while they were higher in resourcefulness ( p = 0.048) and impulse control ( p = 0.028) compared to bipolar II patients. The differences were strong in rapid fatigability, respectively, moderate in the others.
4. Discussion Even when clinically euthymic, bipolar patients continue to describe themselves as more fatigable, less sentimental, more independent, less purposeful, less resourceful, less empathic, less helpful, less purehearted, and have less impulse control than controls. Since all subjects had previously been ill, we cannot determine whether these reflect premorbid personality traits rather than sequelae of previous illness. Bipolar I and II patients are similar in personality on the higher dimensions of temperament and character, but on lower dimensions bipolar II patients are more impulsive, fatigable, less resourceful, and have less impulse control. Lithium has been found to decrease neuroticism, and altered habitual patterns of personality in bipolar patients. Our study and other studies (Strakowski et al., 1992; Young et al., 1995; Osher et al., 1996, 1999)
of bipolar patients with and without lithium treatment have found similar results in temperament. Our results can therefore not be explained by a side effect from lithium treatment. These results indicate that bipolar patients who are apparently euthymic on lithium maintenance continue to have a characteristic cognitive deficit. These findings are consistent with cognitive theories about cognitive deficits in depression in which beliefs that ‘‘I am helpless’’ and ‘‘I am unlovable’’ are regarded as important vulnerability factors in mood disorders (Beck, 1999).
Acknowledgements We thank Barbro Nordqvist-Karlsson for his help in collecting data. References American Psychiatric Association, 1987. Diagnostic and Statistical Manual of Mental Disorders, 3rd ed. rev. American Psychiatric Press, Washington, DC. Beck, A.T., 1999. Cognitive aspects of personality disorders and their relation to syndromal disorders: a psychoevolutionary approach. In: Cloninger, C.R. (Ed.), Personality and Psychopathology. American Psychiatric Press, Washington, D.C, pp. 411 – 430. Cloninger, C.R., 1999. Personality and Psychopathology. American Psychiatric Press, Washington, D.C. Cloninger, C.R., Przybeck, T.R., Svrakic, D.M., Wetzel, R.D.,
134
C. Engstro¨m et al. / Journal of Affective Disorders 82 (2004) 131–134
1994. The Temperament and Character Inventory (TCI): A Guide to its Development and Use. Center for Psychobiology of Personality, Washington University, St. Louis, MO. Cloninger, C.R., Bayon, C., Svrakic, D.M., 1998. Measurement of temperament and character in mood disorders: a model of fundamental states as personality types. J. Affect. Disord. 51 (1), 21 – 32. Cohen, J., 1988. Statistical Powers Analysis for the Behavioral Sciences, 2nd ed. Lawrence Earlbaum Associates, Hillsdale, NJ. Farmer, A.E., Wessely, S., Castle, D., McGuffin, P., 1992. Methodological issues in using a polydiagnostic approach to define psychotic illness. Br. J. Psychiatry 161, 824 – 830. Goodwin, F.K., Jamison, K., 1990. Personality and interpersonal behaviour. In: Goodwin, F.K., Jamison, K. (Eds.), Manic Depressive Illness. Oxford Univ. Press, Oxford, pp. 281 – 317. Osher, Y., Cloninger, C.R., Belmaker, R.H., 1996. TPQ in euthymic manic depressive patients. J. Psychol. Res. 30 (5), 353 – 357. Osher, Y., Lefkifer, E., Kotler, M., 1999. Low persistence in euthymic manic-depressive patients: a replication. J. Affect. Disord. 53, 87 – 90. Richter, J., Bra¨ndstro¨m, S., Przybeck, T., 1999. Assessing perso-
nality: the temperament and character in a cross-cultural comparison between Germany, Sweden and the USA. Psychol. Rep. 84, 1315 – 1330. Stancer, H.C., Furlong, F.W., Godse, D.D., 1970. A longitudinal investigation of lithium as a prophylactic agent for recurrent depressions. Can. Psychiatr. Assoc. J. 15, 29 – 40. Strakowski, S.M., Faedda, G.I., Thoen, M., Goodwin, D.C., Stoll, A.L., 1992. Possible affective-state dependence of the tridimensional personality questionnaire. Psychol. Res. 41 (3), 215 – 226. Strakowski, S.M., Stoll, A.L., Thoen, M., Faedda, G.L., Goodwin, D.C., 1993. The tridimensional personality questionnaire a predictor of six month outcome in first episode mania. Psychol. Res. 48, 1 – 8. Wing, J.K., Babor, T., Brugha, T., Burke, J., Cooper, J.E., Giel, R., Jablenski, A., Regier, D., Sartorius, N., 1990. SCAN: schedules for clinical assessment in neuropsychiatry. Arch. Gen. Psychiatry 47, 589 – 593. Young, T.L., Bagby, R.M., Cooke, R.G., Parke, J.D.A., Levitt, A.J., Joffe, R.T., 1995. A comparison of tridimensional personality questionnaire dimensions in bipolar disorder and unipolar depression. Psychol. Res. 58, 139 – 143.