In order to evaluate the hypothesis that one set of genetic risk factors may be common to disorders and dimensions of temperament, whereas environmental risk factors are disorder specific, we have conducted a genetic analysis of dimensions of temperament and symptoms of depression in about 201 pairs of monozygotic and dizygotic twins. Dimensions of temperament associated with novelty seeking, harm avoidance, reward dependence, and persistence were measured by using the Temperament and Character Instruments developed by Cloninger, and depressive symptoms were measured using the Hospital Anxiety and Depression Scale. Differences among individuals on these measures can be explained by differences in their genes and in their environmental experiences. There are no differences between the sexes in gene action affecting temperament. Each dimension of temperament is genetically dependent, and genetic variations in symptoms of depression are largely dependent on the same factors that affect the temperament. Temperament is closely associated with vulnerability to depressive symptoms. Molecular Psychiatry (2002) 7, 948-953.

Dimensional approaches have been used to describe the fundamental dimensions that underlie the entire domain of normal and pathological personality. We tested the five factor model of personality structure in a sample of Japanese twins, to clarify the contributions of genetic and envi ronment. The revised NEO personality inventory (NEO-PI-R) was administered to 251 twin pairs, ranging in age from 15 to 27 years of age. The NEO-PI-R is a 240-item questionnaire which was developed to assess the dimensions of personality. Univariate genetic analysis showed that the AE model in which phenotypic covariances are explained only by additive genetic (A) and nonshared environment (E) is still a plausible model, and that the relative proportion of genetic influence was comparable to that reported by Loehlin (1992). Multivariate genetic analysis of the Japanese data suggested/revealed that the five factors are genetically dependent on each other and one common genetic factor mediates their interdependence. Previous studies have assumed that they are pheno typically independent and robust. Although there are sampling biases in the present study, it is note worthy that the results for all five factors depicted by the NEO-PI-R were comparable to those reported by Western researchers, and the genetic structure of the five-factor model is complex.

Theoretical assumptions regarding the genetic and environmental structure of personality proposed in Cloninger's seven-factor model of temperament and character were verified in a Japanese sample by using the twin method. The Temperament and Character Inventory (TCI) was administered to 296 twin pairs ranging in age from 14 to 28 years old. Among four temperament dimensions (novelty seeking [NS], harm avoidance [HA], reward dependence [RD], and persistence [PS]), HA and PS showed significant additive genetic contributions and no shared environmental effect, supporting the original theoretical assumption. NS and RD could be explained by either genetic or shared environmental factors with nonshared environment. All three character dimensions (cooperativeness [CO], self-directedness [SD], and self-transcendence [ST]) could be explained exclusively by additive contributions and no shared environmental effect. Multivariate genetic analysis indicated that there were no significant associations between NS, HA, and RD, as the theory predicts, and the genetic components of PS, SD, and CO were derived from those of the temperament dimensions. The fourth genetic component, which had a substantial load specifically on ST and overlapped with PS, was identified. Although most of the nonshared environmental effects were trait-specific, the phenotypic correlation between NS and HA could be explained by nonshared environmental overlap.

Patients with treatment-refractory depression (TRD) have significantly great losses in work productivity and employment. Interpersonal psychotherapy (IPT) is considered an approach for the treatment of TRD. However, the effectiveness of IPT in patients with TRD remains unclear. In this study, we report cases of TRD patients who underwent IPT after a detailed evaluation, along with their employment status. Of 112 patients who experienced 1-week examination administration for TRD at Kyorin University Hospital, which aimed to determine appropriate diagnosis and treatment approaches for each patient, four patients who met the criteria for major depressive disorder according to DSM-IV-TR and were determined suitable for IPT were included in this report. Two patients had moderate, one had mild, and one had remission levels of depressive symptoms according to the Montgomery-Asberg Depression Rating Scale at the time of admission. All four patients completed the scheduled sessions of IPT (6–16 sessions) in the outpatient clinic and achieved remission. All four patients attained full-time employment within 6 months after receiving IPT. This study suggests that the appropriate selection of IPT might be effective for TRD patients, possibly leading to positive outcomes, including work productivity and employment status.