Masanori Enokido

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.

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.

Parental care influences leukocyte telomere length with gender specificity in parents and offsprings

BackgroundThere have been several reports suggesting that adverse childhood experiences such as physical maltreatment and long institutionalization influence telomere length. However, there has been no study examining the relationship of telomere length with variations in parental rearing. In the present study, we examined the relationship of leukocyte telomere length with parental rearing in healthy subjects.MethodsThe subjects were 581 unrelated healthy Japanese subjects. Perceived parental rearing was assessed by the Parental Bonding Instrument consisting of the care and protection factors. Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene.ResultsIn the multiple regression analyses, shorter telomere length in males was related to lower scores of paternal care (β = 0.139, p < 0.05), while that in females was related to lower scores of maternal care (β = 0.195, p < 0.01).ConclusionThe present study suggests that there is linear relationship between parental care and telomere length which covers both lower and higher ends of parental care, and that the effects of parental care on telomere length are gender-specific in parents and offsprings.

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.

Relationship of the FKBP5 C/T polymorphism with dysfunctional attitudes predisposing to depression

FK506-binding protein 51 (FKBP5) is a co-chaperone of the glucocorticoid receptor, and plays an important role in the negative feedback regulation of the hypothalamic-pituitary-adrenal axis. The C/T single nucleotide polymorphism in the intron 2 of the FKBP5 gene affects cortisol secretion, and has been implicated in the pathophysiology of depression. In this study, the relationship of the FKBP5 C/T polymorphism with dysfunctional attitudes predisposing to depression was examined. The subjects were 300 healthy Japanese. The FKBP5 genotypes were determined by a real-time PCR and cycling probe technology for SNP typing. Dysfunctional attitudes were assessed by the 24-item version of the Dysfunctional Attitude Scale (DAS-24), which has the Achievement, Self-control, and Dependency subscales. DAS-24 total scores were significantly higher in the group with the T allele than in that without this allele (p=0.001). Regarding the subscales, scores of the Achievement (p=0.003) and Self-control (p=0.009) subscales, but not those of the Dependency subscale, were significantly higher in the former group than in the latter group. The present study suggests that the FKBP5 C/T polymorphism is implicated in formation of dysfunctional attitudes, especially those about achievement and self-control.

Interaction effect between the BDNF Val66Met polymorphism and parental rearing for interpersonal sensitivity in healthy subjects

Interpersonal sensitivity is defined as undue and excessive awareness of, and sensitivity to, the behaviour 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 characterised 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 in 725 healthy Japanese subjects. 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 polymerase chain reaction-restriction fragment length polymorphism (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.

Effects of perceived affectionless control parenting on working models of the self and other.

Attachment theory contends that insecure working models of the self and other built through negative attachment experiences are predisposing factors for depression and anxiety disorders. Meanwhile, patients with these psychiatric disorders tend to perceive that they received the affectionless control parenting, which is a combination of lack of care and overprotection. To test the hypothesis that the affectionless control parenting impairs the formation of positive working models, we examined the effects of perceived parenting styles on qualities of working models. The subjects were 691 healthy Japanese volunteers. Working models of the self and other were assessed by the Relationship Scales Questionnaire. Perceived parental rearing was evaluated by the Parental Bonding Instrument, which has the care and protection subscales. Parental rearing was classified into one of the four types defined by combinations of levels of care and protection. In all combinations of recipient sexes and parental sexes, the subjects with the affectionless control parenting (low care/high protection) had lower scores of the self-model and other-model than those with the optimal parenting (high care/low protection). The present study suggests that the affectionless control parenting impairs the formation of positive working models of the self and other.

Implication of P-Glycoprotein in Formation of Depression-Prone Personality: Association Study between the C3435T MDR1 Gene Polymorphism and Interpersonal Sensitivity

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 χ2 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.