title: Effect of month of birth on personality traits of healthy Japanese.
abstract: The effect of month of birth on personality traits was investigated in 595 healthy Japanese. Personality traits were evaluated by the Temperament and Character Inventory (TCI). Statistical analyses were conducted in two steps. Firstly, months of the year were divided according to ambient temperature or photoperiod, and TCI scores were compared between month groups by analysis of covariance (ANCOVA) with age as a covariate. Secondly, multiple regression analysis was performed with TCI scores as dependent variables and ambient temperature and photoperiod at birth month and age as independent variables. Both analyses showed that higher ambient temperature at birth month was related to higher scores of self-directedness and persistence in females. Also, higher ambient temperature at birth month was related to lower body mass index (BMI) in females. These results suggest that month of birth affects self-directedness and persistence in healthy Japanese females, and these effects may be mediated by BMI changes associated with ambient temperature at birth month.
authors.affiliation: Health Administration Center, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan. mkamata@med.id.yamagata-u.ac.jp
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kamata
authors.forename: Akihito
authors.initials: A
authors.lastname: Suzuki
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Togashi
authors.forename: Koichi
authors.initials: K
authors.lastname: Otani
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D002910:Chronology as Topic; D004777:Environment; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010551:Personality / Q000502:physiology*; D010555:Personality Inventory / Q000706:statistics & numerical data*; D012016:Reference Values; D017678:Sex Distribution; D013694:Temperament; D013696:Temperature; D055815:Young Adult