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Background: The μ-opioid receptor (MOR) plays an important role in social bonding behaviors, while it is implicated in the pathophysiology of depression. It is shown that the A118G polymorphism (rs1799971) of the MOR gene (OPRM1) causes amino-acid exchange from Asn to Asp, and that this polymorphism is associated with altered mu-opioid receptor function. Meanwhile, sociotropy/autonomy and interpersonal sensitivity are personality vulnerabilities to depression characterized by distinctive interpersonal styles. The present study tested the hypothesis that the functional A118G OPRM1 polymorphism influences these personality traits., Methods: The subjects were 402 physically and mentally healthy Japanese volunteers. Sociotropy and autonomy were measured by the Sociotropy-Autonomy Scale, and interpersonal sensitivity was evaluated by the Interpersonal Sensitivity Measure. The A118G polymorphism of the OPRM1 was determined by the PCR method., Results: In one factor analysis of covariance, there were differences in scores of sociotropy (uncorrected p < .001, corrected p < .003) and interpersonal sensitivity (uncorrected p = .015, corrected p = .045), but not autonomy, among the A/A, A/G, and G/G genotypes. Post hoc LSD tests showed that sociotropy scores were higher in the A/A group than in the A/G (p = .029) and G/G (p < .001) groups, and higher in the A/G group than in the G/G group (p = .004). Interpersonal sensitivity scores were higher in the A/A group than in the A/G (p = .023) and G/G (p = .009) groups., Conclusion: This study suggests that the A118G OPRM1 polymorphism is associated with sociotropy and interpersonal sensitivity, interpersonal vulnerabilities to depression., (© 2022 The Authors. Brain and Behavior published by Wiley Periodicals LLC.)

Aims: The diacylglycerol kinase η gene (DGKH) is one of the few replicated risk genes for bipolar disorder. Meanwhile, specific personality traits, especially openness to experience, have been suggested as premorbid personality traits of the disorder. The aim of the present study was to examine the relation of the DGKH genotype with broad dimensions of personality, to obtain further evidence for its implication in the etiology of bipolar disorder., Methods: The subjects were 319 Japanese healthy volunteers. Personality was assessed by the NEO Personality Inventory-Revised, which has the neuroticism, extraversion, openness to experience, agreeableness and conscientiousness dimensions. The A/G polymorphism of DGKH (rs9525580) was detected by a PCR-RFLP method. The subjects were divided into two groups with respect to the presence or absence of the A allele, which is a putative risk allele for bipolar disorder., Results: The group with the A allele had significantly (p < 0.05) higher scores of openness to experience compared to that without this allele. Scores of other dimensions were not different between the two groups., Limitations: The subjects had a homogeneous but rather specific background, and we did not employ a longitudinal design., Conclusions: The present study shows that a bipolar-risk allele of DGKH is associated with higher openness to experience, providing further evidence for the implication of this gene in the etiology of bipolar disorder., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Telomeres are repetitive DNA sequences located at the ends of chromosomes, and telomere length represents a biological marker for cellular aging. Interpersonal sensitivity, excessive sensitivity to the behavior and feelings of others, is one of the vulnerable factors to depression. In the present study, we examined the effect of interpersonal sensitivity on telomere length in healthy subjects., Methods: The subjects were 159 unrelated healthy Japanese volunteers. Mean age ± SD (range) of the subjects was 42.3 ± 7.8 (30-61) years. Interpersonal sensitivity was assessed by the Japanese version of the Interpersonal Sensitivity Measure (IPSM). Leukocyte telomere length was determined by a quantitative real-time PCR method., Results: Higher scores of the total IPSM were significantly (β = -0.163, p = 0.038) related to shorter telomere length. In the sub-scale analysis, higher scores of timidity were significantly (β = -0.220, p = 0.044) associated with shorter telomere length., Conclusions: The present study suggests that subjects with higher interpersonal sensitivity have shorter leukocyte telomere length, implying that interpersonal sensitivity has an impact on cellular aging.

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., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

The present study examined the associations of working models of the self and other, one of the key concepts of Bowlby's attachment theory, with the seven dimensions of Cloninger's personality model. The subjects were 542 healthy Japanese volunteers. Working models of the self and other were assessed by the Relationship Scales Questionnaire, and the seven dimensions of personality were evaluated by the Temperament and Character Inventory. In the correlation analysis, the self-model was correlated most strongly with self-directedness (SD) (r=0.50, P<0.001) and second strongly with harm avoidance (HA) (r=-0.43, P<0.001), while the other-model was correlated most strongly with cooperativeness (C) (r=0.43, P<0.001) and second strongly with reward dependence (RD) (r=0.41, P<0.001). In the principal component analysis, the self-model formed a group with SD and HA, while the other-model formed a group with C and RD. The present study suggests that the self-model is reflected in SD and HA, while the other-model is reflected in C and RD., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Beck's cognitive theory of depression postulates personality vulnerability factors termed sociotropy and autonomy, which are accompanied by characteristic interpersonal styles. Meanwhile, Bartholomew contends that negative working models of the self and other built through insecure attachment relationships are externalized as distinctive interpersonal styles. The present study examined the relationships of sociotropy and autonomy with the self- and other-models, and attempted to promote understanding of the two personality traits from an attachment perspective., Methods: The subjects were 510 healthy Japanese medical students or hospital staffs. Sociotropy and autonomy were assessed by the Sociotropy-Autonomy Scale, and working models of the self and other were evaluated by the Relationship Scales Questionnaire., Results: The sociotropy score was correlated negatively with the self-model score (β=-0.52, p<0.001) and positively with the other-model score (β=0.11, p<0.01). The autonomy score was correlated positively with the self-model score (β=0.10, p<0.05) and negatively with the other-model score (β=-0.33, p<0.001)., Limitations: It may be risky to generalize the present results to general populations or other ethnic groups., Conclusions: The present study suggests that both sociotropy and autonomy are associated with attachment insecurity, but the marked difference in their correlation patterns with the self- and other-models leads to the distinctive interpersonal styles of the two personality orientations., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Aim: Interpersonal sensitivity is defined as undue and excessive awareness of, and sensitivity to, the behavior and feelings of others. Previous studies suggested that interpersonal sensitivity is one of the vulnerable factors to depression, and that genetic factors and cortisol are involved in the formation of interpersonal sensitivity. On the other hand, P-glycoprotein, which is encoded by the multidrug resistance 1 (MDR1) gene, serves as a barrier to entry and as an active eliminator for xenobiotics and cellular metabolites including cortisol, which is implicated in multiple brain functions. In the present study, we examined the effects of the MDR1 C3435T polymorphism (rs1045642) on interpersonal sensitivity in healthy subjects., Methods: The subjects were 842 healthy Japanese volunteers (mean age = 26.7 years, male/female ratio = 490/352). The C3435T polymorphism of MDR1 gene was detected by a PCR method, and interpersonal sensitivity was assessed by the Interpersonal Sensitivity Measure (IPSM)., Results: The 2-factor analysis of covariance (ANCOVA) showed a significant main effect of the MDR1 genotype on the IPSM scores with a significant interaction between the genotype and gender. The subsequent 1-factor ANCOVA showed that in females the C/C genotype group had higher IPSM scores than the C/T genotype group (p < 0.001) and the T/T genotype group (p < 0.001), and the C/T genotype group had higher IPSM scores than the T/T genotype group (p = 0.014). In males no significant association was found between the MDR1 genotype and the IPSM scores. In allelic analyses using the χ(2) tests, the C allele frequency in females was significantly higher (p < 0.001) in the high IPSM group than in the low IPSM group, while there was no significant difference in the C allele frequency between the high and low IPSM groups in total subjects and males., Conclusion: The present study suggests that the C3435T polymorphism of the MDR1 gene affects the formation of a depression-prone personality trait in Japanese females.

Interpersonal sensitivity is a depression-prone personality trait closely related to anxious attachment, whereas sociotropy and autonomy are personality vulnerability factors in the cognitive theory of depression. In the present study, the relationships of interpersonal sensitivity with sociotropy and autonomy were studied in 362 healthy subjects. Interpersonal sensitivity was assessed using the Interpersonal Sensitivity Measure (IPSM), whereas sociotropy and autonomy were evaluated using the Sociotropy and Autonomy subscales, respectively, of the Sociotropy-Autonomy Scale. The IPSM was significantly correlated with the Sociotropy subscale (β = 0.61, p < 0.001) but not with the Autonomy subscale. All subscales of the IPSM correlated significantly with the Sociotropy subscale, and the correlation for the Separation Anxiety subscale (β = 0.56, p < 0.001) was strongest. The present study suggests that interpersonal sensitivity is correlated with sociotropy but not with autonomy 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., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

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 Beck's concepts of these personality traits, that is, the orientation toward interpersonal relationships of sociotropy, and that toward mastery and independence of autonomy., (Copyright © 2011 Elsevier Inc. All rights reserved.)

There is a growing body of data suggesting that gene-environment interaction is critical in the characterization of personality traits; however, previous studies have not taken into consideration variability in parental rearing as an environmental factor. In this study, we examined the effects of the interaction between the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and parental rearing on personality traits in 710 healthy Japanese subjects. Perceived parental rearing was assessed by the Parental Bonding Instrument (PBI), which consists of the care and protection factors. Assessment of personality traits was performed by the temperament and character inventory (TCI), which has seven dimensions, i.e. novelty seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness and self-transcendence. Parental rearing has significant main effects on some TCI dimensions, but 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, and for both personality traits the partial correlation coefficient was highest in the Met/Met genotype group and lowest in the Val/Val genotype group and the value of the Val/Met genotype group was in the middle. Data from this study suggest that the BDNF Val66Met polymorphism modulates the effects of parental rearing, especially maternal care, on harm avoidance and self-directedness in healthy subjects., (© 2011 The Authors. Genes, Brain and Behavior © 2011 Blackwell Publishing Ltd and International Behavioural and Neural Genetics Society.)

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., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

According to the Cloninger's 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., (Copyright 2009 Elsevier B.V. All rights reserved.)

There have been several studies showing the relationship between sex hormones and personality traits. Cytochrome P450 19 (CYP 19, aromatase) is the rate-limiting enzyme for the conversion of androgens into estrogens, and it has been reported that the C/T single nucleotide polymorphism in the 3'-untranslated region (3'UTR) of CYP19 gene (rs10046) affects dispositions of estradiol and testosterone. Therefore, it is hypothesized that this polymorphism affects personality traits. In the present study, the association of this polymorphism with personality traits was examined in 633 healthy Japanese subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the CYP19 genotype was detected by a PCR-RFLP method. In males, the group with the T allele predictive of elevated levels of estradiol and decreased levels of testosterone had lower scores of harm avoidance than that without the T allele (p=0.015). In females, none of the seven TCI dimensions was different between the two genotype groups. The present study thus suggests that the C/T polymorphism in the 3'UTR of CYP19 gene affects personality trait of harm avoidance in healthy males.

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.

Dopamine and norepinephrine are implicated in the characterization of personality traits. Dopamine-beta-hydroxylase (DBH) is the enzyme responsible for conversion of dopamine to norepinephrine, and thus plays an important role in controlling dispositions of these neurotransmitters. Previous studies have shown that the -1021C/T polymorphism of the DBH gene promoter influences plasma DBH activity. Therefore, we examined the association between the -1021C/T DBH polymorphism and personality traits in 627 Japanese healthy volunteers. The DBH genotypes were identified by a PCR-RFLP method, and personality traits were assessed by the Temperament and Character Inventory (TCI). 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. The present study suggests that the -1021C/T DBH polymorphism affects the personality trait of harm avoidance in healthy females.

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.

There have been several studies suggesting that sex hormones are involved in characterization of human mental function and behaviour. Recently, it has been reported that the -34T/C polymorphism of cytochrome P450 17 (CYP17) gene affects sex hormone dispositions. Therefore, it is possible that the CYP17 -34T/C polymorphism affects personality traits. In the present study, the association of this genetic polymorphism with personality traits was examined in 595 healthy Japanese. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the CYP17 -34T/C polymorphism was detected by a PCR-RFLP method. In males, the scores of novelty seeking, cooperativeness, and self-transcendence were higher in the group with the C allele than in that without this allele. In females, none of the seven TCI dimensions was different between the two genotype groups. The present study thus suggests that the -34T/C polymorphism of the CYP17 gene affects personality traits of healthy males, but not females, and this gender-dependent effect may be mediated by the action of sex hormones such as estradiol and testosterone.

There have been some animal and human data suggesting that excitatory amino acid transporter (EAAT)-2, the major subtype of EAAT, is involved in human mental function and behavior. Recently, it has been shown that the -181 A/C polymorphism in the EAAT2 gene promoter affects plasma glutamate concentrations in humans. In the present study, the association of this genetic polymorphism with personality traits was examined in 575 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character Inventory, and the EAAT2 polymorphism was detected by a PCR-RFLP method. The scores of reward dependence were significantly (p=0.017) lower in the group with the A allele (A/A and A/C) than in that without this allele (C/C). When males and females were analyzed separately, the significant difference between the two genotype groups was observed in females (p=0.021) but not in males. The present study thus suggests that the -181 A/C polymorphism in the EAAT2 gene promoter affects the personality trait of reward dependence in healthy subjects.

There have been several data suggesting that norepinephrine neurotransmission is involved in the characterization of personality traits. Recently, the -3081A/T polymorphism in the promoter region of the norepinephrine transporter (NET) gene affecting promoter activity has been reported. In the present study, we studied the association between this NET polymorphism and personality traits in 553 Japanese healthy subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the NET genotypes were identified by a PCR-RFLP method. Multivariate two-factor analysis of covariance with genotype and gender as factors and with age as a covariate showed no association between the NET genotypes and the TCI dimension scores. The present study thus suggests that the -3081A/T polymorphism in the NET gene promoter is not involved in the characterization of personality traits in healthy subjects.

Influences of parental rearing on the personality traits of healthy subjects were studied in 323 Japanese volunteers. Perceived parental rearing was assessed with the use of the Parental Bonding Instrument, which consists of the factors of care and protection, whereas personality traits were assessed with the use of the Temperament and Character Inventory, which has 7 dimensions. In male subjects, all personality dimensions except for novelty seeking were influenced by parental rearing; in female subjects, only the harm avoidance (HA) and self-directedness (SD) dimensions were affected by parenting. Paternal rearing influenced 3 dimensions in male subjects and 1 dimension in female subjects, whereas maternal rearing influenced 5 dimensions in male subjects and 2 dimensions in female subjects. In male subjects, higher HA was related to higher paternal protection (P < .05), whereas in female subjects, it was related to higher maternal protection (P < .01). In male subjects, lower SD was related to higher paternal protection (P < .05) and lower maternal care (P < .01), whereas in female subjects, it was related to lower paternal care (P < .05) and higher maternal protection (P < .01). These results suggest that parental rearing influences the personality traits of healthy subjects, especially HA and SD, with sex specificity in parents and recipients.

It has been suggested that the central serotonergic activity is implicated in personality traits. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in serotonin synthesis. In the present study, the association between the TPH A218C polymorphism and personality traits assessed by the Temperament and Character Inventory (TCI) was examined in 345 Japanese healthy subjects. The TPH A218C polymorphism was determined by a PCR-RFLP method. There were no significant differences in the seven dimension scores of TCI among the A/A, A/C, and C/C genotype groups by the one-way ANOVA. There was a significant negative correlation between age and the NS scores. Females showed significantly higher scores of HA, RD, and ST, and significantly lower scores of SD than males. The multiple regression analysis using age, gender, and the TPH genotype as independent variables also showed no significant association between any dimension score and the genotype. The present study thus suggests that the TPH A218C polymorphism does not affect personality traits in Japanese healthy subjects.

It has been suggested that personality traits are heritable. The polymorphic cytochrome P450 (CYP) 2C19 metabolizes sex hormones and 5-hydroxytryptamine, which are involved in multiple brain functions. In the present study, the relationship between the CYP2C19 polymorphism and personality traits was examined in 487 Japanese healthy volunteers. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the two mutated alleles causing absent CYP2C19 activity were identified by a PCR-RFLP method. In females, the scores of reward dependence (p=0.026), cooperativeness (p=0.001), and self-transcendence (ST) (p=0.049) were significantly lower in poor metabolizers (PMs) than in extensive metabolizers (EMs). In males, none of the seven TCI dimensions was significantly different between EMs and PMs. The present study thus suggests that the CYP2C19 polymorphism affects personality traits of Japanese females.

It has been suggested that monoamine oxidase A plays an important role in the characterization of personality. Previous studies on the association between the polymorphism of variable number tandem repeat in the promoter region of the monoamine oxidase A gene and personality traits have, however, been unproductive. In the present study, the association between the monoamine oxidase A variable number tandem repeat polymorphism and personality traits assessed by the Temperament and Character Inventory was examined in 324 Japanese volunteers without psychiatric disorders. The low activity allele with three repeats (allele 3) and high activity allele with four repeats (allele 4) were determined by a polymerase chain reaction method. The carriers of allele 3 in males and the homozygotes of allele 3 in females were classified as the low activity group, the heterozygotes of alleles 3 and 4 in females as the medium activity group, and the carriers of allele 4 in males and the homozygotes of allele 4 in females as the high activity group. One-way analysis of variance showed that the scores of novelty seeking (P=0.006) and reward dependence (P=0.013) were significantly higher in the high activity group than in the low activity group. Multiple regression analysis demonstrated that the excess in the high activity allele was significantly associated with higher scores of novelty seeking (P=0.004) and reward dependence (P=0.003). The present study thus suggests that the monoamine oxidase A variable number tandem repeat polymorphism affects novelty seeking and reward dependence in healthy study participants.

Keisuke Noto,1 Akihito Suzuki,1 Toshinori Shirata,1 Yoshihiko Matsumoto,1 Nana Takahashi,1 Kaoru Goto,2 Koichi Otani1 1Department of Psychiatry, Yamagata University School of Medicine, Yamagata 990-9585, Japan; 2Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585, JapanCorrespondence: Toshinori Shirata Email white_gregory000@yahoo.co.jpPurpose: Attachment research shows that attachment experiences with parents in childhood influence the characterization of personality traits. Meanwhile, it is known that mu-opioid receptor function is involved in human attachment. Furthermore, a few studies suggest that the A118G polymorphism of the mu-opioid receptor gene (OPRM1) is associated with altered mu-opioid receptor function. Thus, we examined if the OPRM1 polymorphism moderates the sensitivity to parental behaviors and thereby contributes to the characterization of personality traits.Materials and Methods: Participants were 725 healthy Japanese. Parenting practices of their parents were evaluated by the Parental Bonding Instrument (PBI) with the care and protection subscales. Personality was evaluated using the Temperament and Character Inventory (TCI). The OPRM1 A118G polymorphism was detected by a PCR method.Results: Multiple regression analyses revealed significant effects of the interaction between the OPRM1 genotype and maternal protection on scores of the self-directedness and cooperativeness dimensions, while significant main effects of the OPRM1 genotype on scores of the TCI were not found. Further analyses showed that there were significant negative correlations between maternal protection scores and the two dimensional scores in the A/A and A/G genotypes with higher correlation coefficients in the former, but not in the G/G genotype.Conclusion: The present study suggests that the OPRM1 polymorphism contributes to the characterization of personality traits by moderating the sensitivity to parental behaviors, especially maternal protection.Keywords: OPRM1, attachment, personality, PBI, TCI, gene–environment interaction

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]

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]

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]