Naoshi Shibuya

Association study between a functional polymorphism of FK506-binding protein 51 (FKBP5) gene and personality traits in healthy subjects

Previous studies have shown that the function of hypothalamic-pituitary-adrenal (HPA) axis is involved in the characterization of personality traits. FK506-binding protein 51 (FKBP51 or FKBP5) is a co-chaperone of heat-shock protein 90, and plays an important role in the negative feedback regulation of HPA axis function. It has been reported that a C/T single nucleotide polymorphism in the intron 2 of FKBP5 gene (rs1360780) affects FKBP5 protein levels and cortisol response to dexamethasone and psychological stress tests. Therefore, it is hypothesized that the FKBP5 polymorphism affects personality traits. In the present study, we studied the association between this polymorphism and personality traits in 826 Japanese healthy subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the FKBP5 genotype was detected by a real-time PCR and cycling probe technology for SNP typing. In total subjects, the group with the T allele predictive of impaired negative feedback regulation of the HPA axis had higher scores of harm avoidance (HA) (p=0.043) and lower scores of cooperativeness (CO) (p=0.019) compared to that without the T allele. The T allele was associated with higher scores of HA in females (p=0.020) and lower scores of CO in males (p=0.015). The present study thus suggests that the FKBP5 polymorphism affects HA and CO in healthy subjects, with gender specificity.

Relationship between leukocyte telomere length and personality traits in healthy subjects

BACKGROUND It has been shown that certain personality traits are related to mortality and disease morbidity, but the biological mechanism linking them remains unclear. Telomeres are tandem repeat DNA sequences located at the ends of chromosomes, and shorter telomere length is a predictor of mortality and late-life disease morbidity. Thus, it is possible that personality traits influence telomere length. In the present study, we examined the relationship of leukocyte telomere length with personality traits in healthy subjects. SUBJECTS AND METHODS The subjects were 209 unrelated healthy Japanese who were recruited from medical students at 4th-5th grade. Assessment of personality traits was performed by the Revised NEO Personality Inventory (NEO-PI-R) and the Temperament and Character Inventory (TCI). Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene. RESULTS In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of neuroticism (P<0.01) and conscientiousness (P<0.05) of the NEO-PI-R, and lower scores of harm avoidance (P<0.05) and reward dependence (P<0.05) of the TCI. CONCLUSIONS The present study suggests that leukocyte telomere length is associated with some personality traits, and this association may be implicated in the relationship between personality traits and mortality.

Parental overprotection engenders dysfunctional attitudes about achievement and dependency in a gender-specific manner

BackgroundIt has been suggested that dysfunctional attitudes, cognitive vulnerability to depression, have developmental origins. The present study examined the effects of parental rearing on dysfunctional attitudes in three areas of life with special attention to gender specificity.MethodsThe subjects were 665 Japanese healthy volunteers. Dysfunctional attitudes were assessed by the 24-item Dysfunctional Attitude Scale, which has the Achievement, Dependency and Self-control subscales. Perceived parental rearing was assessed by the Parental Bonding Instrument, which has the Care and Protection subscales.ResultsHigher scores of the Achievement (β = 0.293, p < 0.01) and Dependency (β = 0.224, p < 0.05) subscales were correlated with higher scores of the Protection subscale in the combination of mother and daughter, but not in other combinations of parents and recipients. Scores of the Self-control subscale were not correlated with paternal or maternal rearing scores.ConclusionsThe present study suggests that parental overprotection engenders dysfunctional attitudes about achievement and dependency in a gender-specific manner.

Parental overprotection increases sociotropy with gender specificity in parents and recipients

BACKGROUND There have been few studies which examined the developmental origins of cognitive vulnerability of depression. The purpose of the present study was to examine the effects of parental rearing on sociotropy and autonomy, the personality vulnerability factors in the cognitive theory of depression. METHODS The subjects were 416 healthy subjects. Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which has care and protection factors, and sociotropy and autonomy were assessed by the Sociotropy-Autonomy Scale. RESULTS In males, neither sociotropy nor autonomy was affected by paternal rearing or maternal rearing. In females, higher levels of sociotropy were related to higher maternal protection (β=0.308, p<0.01), while autonomy was affected neither by paternal rearing nor by maternal rearing. LIMITATIONS Parental behaviors not covered by the PBI may affect formation of autonomy. CONCLUSIONS The present study suggests that parental overprotection increases sociotropy with gender specificity in parents and recipients.

The −67 A/T promoter polymorphism in the dopamine transporter gene affects personality traits of Japanese healthy females

Dopamine transporter (DAT) plays a major role in terminating dopamine neurotransmission, which may be involved in the characterization of personality traits. Recently, polymorphisms of the promoter region (-67 A/T) and intron 8 (40-bp variable number of tandem repeats, VNTRs) in the DAT gene were reported to affect DAT expression. In the present study, we examined the associations of these polymorphisms with personality traits in 654 healthy Japanese. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the DAT polymorphisms were identified by PCR-based methods. Regarding the -67 A/T promoter polymorphism, the females without the A allele predictive of high DAT activity had lower scores of self-directedness (p=0.005) and cooperativeness (p=0.038) than those with the A allele. In males, none of the TCI scores was different between the two genotype groups. The intron 8 VNTR polymorphism did not affect any TCI score either in males or in females. The present study thus suggests that the -67 A/T promoter polymorphism, but not intron 8 VNTR polymorphism, in the DAT gene affects personality traits of Japanese healthy females.

Functional polymorphism of the GTP cyclohydrolase 1 gene affects the personality trait of novelty seeking in healthy subjects

GTP cyclohydrolase 1 (GCH1) is the initial and rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin, which is an essential cofactor for biosynthetic enzymes of dopamine, serotonin, and nitric oxide. In the present study, the association of functional polymorphism of the GCH1 gene (C+243T, rs841) with personality traits was examined in 902 healthy Japanese subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the GCH1 genotype was detected by a PCR-RFLP method. There were no significant main effects of the GCH1 genotype on the seven TCI dimension scores, but significant interaction effects between the GCH1 genotype and gender were found on the scores of novelty seeking. Post-hoc analysis revealed that males with the C/C genotype had higher scores of novelty seeking than those with the C/T genotype or those with the T/T genotype, while in females the scores of novelty seeking were not different among the genotype groups. The present study thus suggests that the C+243T polymorphism of the GCH1 gene affects the personality trait of novelty seeking in males.

Dysfunctional parenting styles increase interpersonal sensitivity in healthy subjects.

The effects of dysfunctional parenting styles on interpersonal sensitivity were studied in 640 Japanese volunteers. Interpersonal sensitivity was assessed by the Interpersonal Sensitivity Measure (IPSM), and perceived parental rearing was evaluated by the Parental Bonding Instrument (PBI), which is consisted of care and protection factors. Parental rearing was classified into 4 types, i.e., optimal parenting (high care/low protection), affectionate constraint (high care/high protection), neglectful parenting (low care/low protection), and affectionless control (low care/high protection). Males with paternal affectionless control showed higher total IPSM scores than those with paternal optimal parenting (p = 0.022). Females with maternal affectionate constraint (p = 0.001), neglectful parenting (p = 0.022), and affectionless control (p = 0.003) showed higher total IPSM scores than those with maternal optimal parenting. In males and females, dysfunctional parenting styles by the opposite-sex parents did not affected total IPSM scores. The present study suggests that in both males and females interpersonal sensitivity is increased by dysfunctional parenting styles by the same-sex parents.

Relationship of the 24-item Dysfunctional Attitude Scale with the Temperament and Character Inventory in healthy subjects

Abstract Background: The 24-item Dysfunctional Attitude Scale (DAS-24) has three subscales to evaluate dysfunctional attitudes predisposing to depression in the areas of achievement, dependency and self-control. Aim: The purpose of the present investigation was to characterize the three subscales in relation to broad dimensions of personality. Methods: The subjects were 528 healthy Japanese volunteers. Personality assessment was conducted by the Temperament and Character Inventory (TCI), which has seven dimensions. The correlations of the DAS-24 subscales with the TCI dimensions were examined by the multiple regression analysis. Results: All DAS-24 subscales had negative correlations with the self-directedness dimension. However, the three subscales had differential patterns of correlations with the reward dependence, persistence, cooperativeness and harm avoidance dimensions. Conclusions: The present study suggests that dysfunctional attitudes measured by the DAS-24 are closely related to low self-directedness of the TCI. Also, the differential patterns of correlations with some TCI dimensions support the content-specificity of the three subscales.

Association study between a functional polymorphism of tyrosine hydroxylase gene promoter and personality traits in healthy subjects.

According to the Cloningers theory, personality consists of temperaments, which are automatic emotional reactions and habits, and characters, which are the self-concepts about goals and values. It has been suggested that temperaments are highly heritable and related to catecholaminergic neurotransmission. Tyrosine hydroxylase (TH) is the initial and rate-limiting enzyme in the biosynthesis of catecholamines such as dopamine and norepinephrine, which are deeply involved in human mental functions and behaviors. It has recently been reported that the C-824T single nucleotide polymorphism in the promoter region of the TH gene (rs10770141) affects promoter activity of the TH gene and urinary catecholamine levels. In the present study, the association of this polymorphism with personality traits was examined in 740 healthy Japanese subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the TH genotype was detected by a PCR-RFLP method. In total subjects, there were no significant differences in the seven TCI dimension scores between the TH genotype groups. In males, the subjects with the T allele predictive of elevated levels of dopamine and norepinephrine had lower scores of novelty seeking than those without this allele, while in females none of the TCI scores was different between the two genotype groups. The present study thus suggests that the C-824T polymorphism in the TH gene promoter may affect the personality trait of novelty seeking in healthy males. However, taken the effects of multiple comparisons into account, the present result should be interpreted with caution, necessitating a replication in a different sample.

Relationships of sociotropy and autonomy with dimensions of the Temperament and Character Inventory in healthy subjects

The relationships of sociotropy and autonomy, the 2 personality traits postulated as vulnerability factors for depression, with 7 dimensions of the Temperament and Character Inventory, a comprehensive measure of personality, were studied in 305 healthy subjects. Sociotropy and autonomy were assessed by the sociotropy and autonomy subscales, respectively, of the original 60-item Sociotropy-Autonomy Scale. In multiple regression analysis, sociotropy was significantly correlated with higher harm avoidance, reward dependence (RD), and self-transcendence (ST), and lower self-directedness; and the correlation was strongest with higher RD (β = 0.27) and second strongest with lower self-directedness (β = -0.25). Meanwhile, autonomy was significantly correlated with higher persistence and ST, and lower RD; and the correlations were especially strong with higher ST (β = 0.37) and lower RD (β = -0.28). These results support Becks concepts of these personality traits, that is, the orientation toward interpersonal relationships of sociotropy, and that toward mastery and independence of autonomy.