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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. [ABSTRACT FROM AUTHOR]

P-glycoprotein, which is encoded by the multidrug resistance 1 (MDR1) gene, serves as a barrier to entry and as an active elimination for xenobiotics and cellular metabolites including cortisol, which is implicated in multiple brain functions. Meanwhile, previous studies suggested that genetic factors and cortisol are involved in formation of interpersonal sensitivity, a personality trait predisposing to depression. In the present study, we examined the effects of the C3435T MDR1 polymorphism on interpersonal sensitivity. The subjects were 842 healthy Japanese volunteers. The mean age ±SD of the subjects was 26.7±8.1 (490 males and 352 females). The C3435T polymorphism of MDR1 gene was detected by a PCR method, and interpersonal sensitivity was assessed by the Interpersonal Sensitivity Measure (IPSM). In total subjects, the C allele of the C3435T MDR1 polymorphism was associated with higher scores of the IPSM. In females the C/C genotype group had higher IPSM scores than the C/T genotype group and the T/T genotype group, and the C/T genotype group had higher IPSM scores than the T/T genotype group. In males no significant association was found between the MDR1 genotype and the IPSM scores. The present study suggests that the C3435T polymorphism of the MDR1 gene affects formation of a depression-prone personality trait in Japanese females. [ABSTRACT FROM AUTHOR]

Interpersonal sensitivity is defined as undue and excessive awareness of, and sensitivity to, the behavior and feelings of others and is one of the vulnerable factors to depression. In a twin study, it was suggested that this personality trait was characterized by both genetic and environmental factors. In the present study, we examined the effects of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on interpersonal sensitivity. The subjects were 725 unrelated healthy Japanese volunteers (mean age±SD=27.1±8.5, 405 males and 320 females). Assessment of interpersonal sensitivity was performed by the Japanese version of the Interpersonal Sensitivity Measure (IPSM). Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. The BDNF polymorphism was detected by the PCR-RFLP method. There was no main effect of the BDNF genotype on the IPSM score, while the PBI factors except maternal care had significant main effect on the IPSM score. There was significant interaction effect between the BDNF genotype and maternal care of the PBI on the IPSM score. Post-hoc analysis of simple slopes showed that the negative relationship between the IPSM score and maternal care was strongest and significant in the Met/Met genotype group, intermediate in the Val/Met genotype group, and weakest in the Val/Val genotype group. The present study suggests that the interaction between the BDNF Val66Met polymorphism and parental rearing, especially maternal care, influences interpersonal sensitivity in healthy subjects. [ABSTRACT FROM AUTHOR]

It has been reported 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. The subjects were 209 unrelated physically healthy Japanese who were recruited from medical students at 4th-5th grade. None had psychiatric disorders. 128 subjects were males, and 81 were females. The mean±SD (range) of age was 23.3±1.7 (20-30) years. Personality traits were assessed 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. In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of Neuroticism (β=0.208, p<0.01) and Conscientiousness (β=0.146, p<0.05) of the NEO-PI-R, and lower scores of Harm avoidance (β=0.144, p<0.05) and Reward dependence (β=0.170, p<0.05) of the TCI. 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. [Copyright &y& Elsevier]

Aims: There is a growing body of data suggesting the gene-environment interaction in the characterization of personality traits, but variation in ordinary parental rearing among environmental factors has not been focused yet. We examined the effects of the interaction between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on personality traits. Methods: Subjects were 710 Japanese healthy volunteers. Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. Personality assessment was performed by the Temperament and Character Inventory (TCI), which has 7 dimensions, i.e., novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness, and self-transcendence. The BDNF Val66Met polymorphism was detected by the PCR-RFLP method. Results: Parental rearing has significant main effects on all TCI dimensions except novelty seeking, while no significant main effects of the BDNF genotype on the TCI scores were found. The interaction between the BDNF genotype and maternal care of the PBI had significant effects on harm avoidance and self-directedness of the TCI. Post-hoc analyses showed that decreased maternal care was correlated with increased harm avoidance and decreased self-directedness in most of the genotype groups, and for both personality traits the correlation was highest in the Met/Met genotype and lowest in the Val/Val genotype and that for the Val/Met genotype was in between the two values. Conclusion: The present study suggests that the BDNF Val66Met polymorphism moderates the effects of parenting rearing, especially maternal care, on harm avoidance and self-directedness in healthy subjects. [ABSTRACT FROM AUTHOR]

Introduction: Dopamine and norepinephrine are implicated in the characterization of personality traits. Dopamine-β-hydroxylase (DBH) is the enzyme responsible for conversion of dopamine to norepinephrine. Previous studies have shown that the -1021C/T polymorphism of the DBH gene promoter influences plasma DBH activity. Few studies investigated the association between this polymorphism and personality traits. Aim: To examine the association between the -1021C/T DBH polymorphism and personality traits in healthy volunteers. Methods: The participants were 627 Japanese unrelated volunteers. The subjects with present psychiatric disorders or past history of psychiatric disorders according to the DSM-IV were excluded. The DBH genotypes were identified by a PCR-RFLP method, and personality traits were assessed by the Temperament and Character Inventory (TCI). The study protocol was approved by the Ethics Committee of Yamagata University School of Medicine, and all subjects provided written informed consent to participate. Results: In the two-factor analysis of covariance with the DBH genotype and sex as factors and with age as a covariate, there was no main effect of the DBH genotype on any TCI score, while the interaction between the factors was significant in harm avoidance. In the post-hoc analysis, the group with the T allele predictive of lower DBH activity had higher scores of harm avoidance than that without the T allele in females (p=0.006), but not in males. Conclusion: The present study suggests that the -1021C/T DBH polymorphism affects the personality trait of harm avoidance in healthy females. [ABSTRACT FROM AUTHOR]

Aims: 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 healthy subjects. Methods: Subjects were 826 Japanese healthy volunteers. 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. Results: 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 (p=0.043) and lower scores of cooperativeness (p=0.019) compared to that without the T allele. The T allele was associated with higher scores of harm avoidance in females (p=0.020) and lower scores of cooperativeness in males (p=0.015). Conclusion: The present study thus suggests that the FKBP5 polymorphism affects harm avoidance and cooperativeness in healthy subjects, with gender specificity. [ABSTRACT FROM AUTHOR]

Aims: Previous studies have shown that the function of hypothalamic-pituitary-adrenal (HPA) axis is involved in the characterization of personality traits. Glucocorticoid receptor (GR) is the most important regulator of the HPA axis negative feedback system, and several polymorphisms of the GR gene are associated with altered glucocorticoid sensitivity. In the present study, we examined the associations between the GR polymorphisms and personality traits in healthy subjects. Methods: Subjects were 880 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character Inventory (TCI). Two polymorphisms of the GR gene, i.e., G/C SNP in the intron 2 (BcII polymorphism, rs41423247) and A/G SNP in the exon 9β (9β polymorphism, rs6198), were detected by a real-time PCR and cycling probe technology for SNP typing. Results: The genotype distributions were G/G=614, G/C=240, and C/C=26 for the BcII polymorphism, and A/A=879 and A/G=1 for the 9β polymorphism, respectively. There were no significant associations between the BcII genotype groups in any TCI dimension score. Conclusion: The present study suggests that these two GR polymorphisms (BcII and 9β polymorphism) are not involved in the characterization of personality traits in healthy subjects. [ABSTRACT FROM AUTHOR]