Nobuhiko Kijima

Is the genetic structure of human personality universal? A cross-cultural twin study from North America, Europe, and Asia.

This study examined whether universality of the 5-factor model (FFM) of personality operationalized by the Revised NEO Personality Inventory is due to genetic influences that are invariant across diverse nations. Factor analyses were conducted on matrices of phenotypic, genetic, and environmental correlations estimated in a sample of 1,209 monozygotic and 701 dizygotic twin pairs from Canada, Germany, and Japan. Five genetic and environmental factors were extracted for each sample. High congruence coefficients were observed when phenotypic, genetic, and environmental factors were compared in each sample as well as when each factor was compared across samples. These results suggest that the FFM has a solid biological basis and may represent a common heritage of the human species.

GENETIC AND ENVIRONMENTAL STRUCTURE OF CLONINGER'S TEMPERAMENT AND CHARACTER DIMENSIONS

The multivariate genetic and environmental structure of Cloningers Temperament and Character Inventory (TCI) was investigated in a sample of 617 pairs of adolescent and young adult twins from Japan. Additive genetic factors accounted for 22% to 49% of the variability on all TCI temperament scales. Although the theory predicts lower heritability for the character scales, all character subscales had a substantial genetic contribution, and nonshared environmental influences accounted for the remainder. Multivariate genetic analyses showed that several subscales used to define one dimension shared a common genetic basis with subscales defining others. Using the degree of shared genetic influence as the basis to rearrange the TCI subscales into new dimensions, it was possible to create genetically independent scales. The implications for personality measurement, theory, and molecular genetic research are discussed.

Reliability and validity of the Japanese version of the Temperament and Character Inventory.

The Temperament and Character Inventory was translated into Japanese, and, to confirm the psychometric properties of the inventory, three samples were recruited from a nonpatient population. In nonpatient population A (N = 555), the full version (240 items) of the inventory with dichotomous measuring, along with the General Health Questionnaire and the Social Desirability Scale, were distributed to the subjects. Factor analyses of the subscales showed that the factor structure of the inventory was consistent with Cloningers theory. Correlations of the scale scores with the General Health Questionnaire and the Social Desirability Scale scores were almost negligible, indicating that the scale is resistant to the current psychopathology and response bias. In this and the other two university student samples (ns = 395 and 377), Cronbach coefficients α of the scale scores were substantially high except for the short version (125 items) of the inventory with dichotomous measures. The Japanese version of the inventory appears to have internal reliability and content and construct validity in a Japanese population.

Temperament and Character Inventory (TCI) as predictors of depression among Japanese college students.

To examine the predictive power of Cloningers psychobiology model of depression, 167 Japanese college students were studied on two occasions, with an interval of approximately three months. At Time 1 (T1), the Temperament and Character Inventory (TCI) and Self-rating Depression Scale (SDS) were distributed. At Time 2 (T2), the SDS was distributed again. The T2 SDS score was positively correlated with Harm Avoidance and negatively correlated with Reward Dependence and Self-directedness at T1. However, after controlling for the T1 SDS score, the T2 SDS score was predicted only by T1 Self-directedness. These data suggest that lower Self-directedness can be predictive of depression, whereas higher Harm Avoidance and lower Reward Dependence are state-dependent.

Factor structures of the Zung Self-Rating Depression Scale (SDS) for undergraduates

In order to categorize the items of the Zung Self-Rating Depression Scale (SDS) so as to allow the construction of subscales, the Japanese version of the SDS was administered to a total of 2,258 undergraduates. Principal-component analyses of the SDS extracted three factors interpretable as cognitive, affective, and somatic symptoms. The SDS was then administered to 597 undergraduates in order to cross-validate the factor structures. The coefficient of congruence and the goodness-of-fitness index generated by a confirmatory factor analysis showed good cross-validity of the factor structures.

Correlations between the temperament and character inventory and the self-rating depression scale among Japanese students

The Temperament and Character Inventory measures four dimensions of temperament and three of character. The 125-item short version and the Self-rating Depression Scale were administered to 306 Japanese students. Their scores on the latter were significantly highly correlated with the scores on both temperament and character scales, positively correlated with Harm-Avoidance score, and negatively correlated with Self-directedness and Cooperativeness scores. It is suggested that scores on depression were related to Harm-Avoidance, particularly to fatigability, and immaturity of the autonomous self and cooperative interpersonal relationship.

Different personalities between depression and anxiety

We examined the different personality dimensions between depression and anxiety with Cloningers seven-factor model of temperament and character. The Temperament and Character Inventory (TCI), which measures four temperament and three character dimensions of Cloningers personality theory (125-item short version), the Self-rating Depression Scale (SDS), and the State-Trait Anxiety Inventory (STAI) were administered to 223 Japanese students. With hierarchical regression analysis, the SDS score was predicted by scores of Harm-Avoidance, Self-Directedness, and Self-Transcendence, even after controlling for the STAI score. The STAI score was predicted by scores of Self-Directedness and Cooperativeness, even after controlling for the SDS score. More importance should be attached to these dimensions of character because they might contribute to both depression and anxiety.

Genetic and Environmental Etiology of Effortful Control

We examined whether effortful control (EC), a temperament proposed by Rothbart and Bates (1998), has genetically coherent structure. A self-report measure of EC was administered to 450 Japanese twins (151 males and 299 females, ages 17 to 32 years) including 152 monozygotic and 73 dizygotic pairs. Univariate genetic analysis revealed that AE model fit best for the total EC as well as its subscales. The heritability estimate for total EC was 49%, and the estimates for subscales ranged between 32% and 45%. Multivariate genetic analysis revealed that the subscales of EC were genetically correlated to a high degree and environmentally correlated to a moderate degree. These results suggest that EC has substantial genetic basis and genetically coherent structure, supporting the validity of the construct. The implications to molecular genetic study and study of psychopathology were discussed.

Precedents of perceived social support: Personality and early life experiences

In order to examine the effects of personality and early life experiences on perceived social support, a total of 97 young Japanese women were investigated. Current interpersonal relationships were measured by an interview modified from Henderson et al.’s Interview Schedule for Social Interaction (ISSI). Personality was measured by Cloninger et al.’s Temperament and Character Inventory. Early life experiences at home and outside of home were also identified in the interview. The number of sources of perceived support was correlated with self‐directness, while satisfaction with perceived support was correlated with novelty seeking and with low harm avoidance. No early life experiences — early loss of a parent, perceived parenting, childhood abuse experiences, experiences of being bullied and/or other life events — showed significant correlations with the number or satisfaction of supportive people. The quantity and quality of perception of social support differ in their link to personality, and perceived social support may, to some extent, be explainable in terms of personality.

Frequencies of Child Abuse in Japan: Hidden but Prevalent Crime

A total of 98 women newly employed by a company in Tokyo were interviewed and asked to recall the frequency of abuse they experiences as children. If the abuse is defined as an act occurring at least several times a month, the rates of the fathers’emotional neglect, threat, shaming the children, slapping, punching with a fist, kicking, hitting with an object, and burning were 5%, 3%, 1%, 4%, 3%, 0%, 0%, and 0%, respectively, whereas the corresponding rates of the mothers’ acts were 9%, 5%, 2%, 0%, 1%, 0%, 1%, and 0%, respectively. None of the children who had been abused at least several times a month reported having sought other people’s help. This study suggests that child abuse in Japan is no less prevalent than in the Western countries and that most abuse cases are unidentified and therefore go unrelieved by intervention.