Influence of HTR2A polymorphisms and parental rearing on personality traits in healthy Japanese subjects

Personality differences in patients with and without gallstones

OBJECTIVE

Presence of gallstones is associated with a range of risk factors that have previously shown associations with personality traits. Our aim was to assess the differences in personality traits between the patients with and without gallstones.

METHODS

This study used a case-control design with 308 participants from the general population, 68.2% female, mean age 49.2 (SD 9.24) years, of whom 154 (50%) participants had asymptomatic gallstones. Personality was assessed with the Temperament and Character Inventory - Revised - 140 (TCI-R-140) and depression with the Center for Epidemiological Study of Depression Scale (CESD). Cut-off ≥16 on the CES-D was used as an exclusion criterion. Subjects were also checked for metabolic risk factors and sociodemographic characteristics.

RESULTS

The group with gallstones had significantly more pronounced metabolic risk factors and higher prevalence of smoking and alcohol usage in comparison with the group without gallstones. This group also exhibited higher temperament dimension Harm avoidance (HA) and lower character dimension Self-directedness (SD). Metabolic variables differed based on character dimension Cooperativeness (CO), smoking based on temperament dimensions Novelty seeking (NS) and HA, and alcohol usage on dimension NS within the gallstones group. In the logistic regression, controlled for smoking, alcohol usage and metabolic variables, temperament dimension HA was shown to be a significant predictor of the presence of gallstones.

CONCLUSION

Our findings indicate that personality may be associated with the presence of gallstones. Future longitudinal studies addressing the complex interplay of personality traits, psychological mechanisms and the associated behavioral, metabolic and neurobiological factors, are needed.

Associations and interactions of the serotonin receptor genes 5-HT1A, 5-HT2A, and childhood trauma with alexithymia in two independent general-population samples

Previous studies suggested that childhood trauma and a disturbed serotonergic neurotransmission are involved in the pathogenesis of alexithymia. Specifically, genetic polymorphisms of the serotonin receptors 5-HT1A and 5-HT2A were found to be associated with alexithymia. However, it is unclear whether these factors show main or interaction effects with childhood trauma on alexithymia. Data from two independent general-population cohorts of the Study of Health in Pomerania (SHIP-Trend: N=3,706, Age: range=20-83, 51.6% female, SHIP-LEGEND: N=2,162, Age: range=20-80, 52.5% female) were used. The Toronto Alexithymia Scale-20 (TAS-20) and the Childhood Trauma Questionnaire (CTQ) were applied. Genotypes of rs6295 of 5-HT1A and rs6311 of 5-HT2A were determined. Ordinary least-squared regression models with robust standard errors were applied to investigate associations of the main and interaction effects of childhood maltreatment and the polymorphisms with alexithymia. Childhood trauma, but none of the investigated polymorphisms showed main effects on alexithymia. However, childhood trauma showed significant CTQ sum score x rs6295 interactions in male subjects in both samples such that the presence of the G-allele diminished the CTQ associated increase in the TAS-20 sum scores. Our results support a strong role of early life stress and interactions with rs6295 on alexithymic personality features at least in male subjects.

Novelty Seeking and Drug Addiction in Humans and Animals: From Behavior to Molecules

Global treatment of drug addiction costs society billions of dollars annually, but current psychopharmacological therapies have not been successful at desired rates. The increasing number of individuals suffering from substance abuse has turned attention to what makes some people more vulnerable to drug addiction than others. One personality trait that stands out as a contributing factor is novelty seeking. Novelty seeking, affected by both genetic and environmental factors, is defined as the tendency to desire novel stimuli and environments. It can be measured in humans through questionnaires and in rodents using behavioral tasks. On the behavioral level, both human and rodent studies demonstrate that high novelty seeking can predict the initiation of drug use and a transition to compulsive drug use and create a propensity to relapse. These predictions are valid for several drugs of abuse, such as alcohol, nicotine, cocaine, amphetamine, and opiates. On the molecular level, both novelty seeking and addiction are modulated by the central reward system in the brain. Dopamine is the primary neurotransmitter involved in the overlapping neural substrates of both parameters. In sum, the novelty-seeking trait can be valuable for predicting individual vulnerability to drug addiction and for generating successful treatment for patients with substance abuse disorders.

No association between a polymorphism in the serotonin receptor 2B (HTR2B) gene and personality traits in healthy Japanese subjects

AIM

The brain neurotransmitter serotonin affects many aspects of human behavior, including personality traits. Because the serotonin receptor 2B (HTR2B) gene has recently been associated with impulsivity, we investigated the potential association between the rs10194776 and Q20* polymorphism in the HTR2B gene and personality traits in healthy subjects.

METHODS

A total of 1,171 healthy Japanese subjects were enrolled in this study. Their personality traits were evaluated using the Temperament and Character Inventory (TCI), and the rs10194776 and Q20* genotype was determined using real-time polymerase chain reaction.

RESULTS

There was a significant main effect of the rs10194776 polymorphism on harm avoidance and self-directedness in females (p = 0.037 and p = 0.043, respectively). However, these differences were insignificant after a Bonferroni correction. Subjects carrying the minor allele of the Q20* polymorphism were nonexistent.

CONCLUSION

The results of the present study suggest that the HTR2B polymorphism is not likely to be associated with personality traits, including novelty seeking and impulsivity.

Temperament and character in euthymic major depressive disorder patients: the effect of previous suicide attempts and psychotic mood episodes

OBJECTIVE

The purpose of this study was to examine personality traits of patients with major depressive disorder and explore the possible connections between personality and clinical and sociodemographic variables.

METHODS

The sociodemographic and clinical properties of 80 patients with major depression, who were euthymic according to Hamilton Depression Scale scores, were recorded. Their personality was evaluated by using Temperament and Character Inventory and results were compared with 80 age- and sex-matched healthy controls. We used general linear model analysis to evaluate the manner in which the variables contributed to TCI scores.

RESULTS

Remitted depressive patients scored significantly lower on on self-directedness and higher on harm avoidance than HC. Previous suicide attempts had a main effect only on harm avoidance while previous psychotic mood episodes were significantly associated with novelty seeking, self-directedness and cooperativeness. With respect to numeric clinical variables, only duration of illness was significantly and negatively correlated with NS and RD scores.

CONCLUSION

Patients with euthymic major depressive disorder may have significantly different personality traits than the normal population, and patients with different clinical and sociodemographic characteristics may show different personality patterns. In addition, assessment of major depressed patients by means of the Temperament and Character Inventory may be helpful to get a deeper insight into those personality traits underlying suicidality and the emergence of psychotic mood episode.

Serotonin receptor expression in human prefrontal cortex: balancing excitation and inhibition across postnatal development

Serotonin and its receptors (HTRs) play critical roles in brain development and in the regulation of cognition, mood, and anxiety. HTRs are highly expressed in human prefrontal cortex and exert control over prefrontal excitability. The serotonin system is a key treatment target for several psychiatric disorders; however, the effectiveness of these drugs varies according to age. Despite strong evidence for developmental changes in prefrontal Htrs of rodents, the developmental regulation of HTR expression in human prefrontal cortex has not been examined. Using postmortem human prefrontal brain tissue from across postnatal life, we investigated the expression of key serotonin receptors with distinct inhibitory (HTR1A, HTR5A) and excitatory (HTR2A, HTR2C, HTR4, HTR6) effects on cortical neurons, including two receptors which appear to be expressed to a greater degree in inhibitory interneurons of cerebral cortex (HTR2C, HTR6). We found distinct developmental patterns of expression for each of these six HTRs, with profound changes in expression occurring early in postnatal development and also into adulthood. However, a collective look at these HTRs in terms of their likely neurophysiological effects and major cellular localization leads to a model that suggests developmental changes in expression of these individual HTRs may not perturb an overall balance between inhibitory and excitatory effects. Examining and understanding the healthy balance is critical to appreciate how abnormal expression of an individual HTR may create a window of vulnerability for the emergence of psychiatric illness.

Association between DARPP-32 gene polymorphism and personality traits in healthy Chinese-Han subjects

The 32-kDa dopamine- and cAMP-regulated phosphoprotein (DARPP-32) is a key signaling factor in several neurotransmitter pathways (including dopamine and serotonin) that impact personality traits. Therefore, different DARPP-32 alleles may influence the biological determination of distinct personality types. We established an association between the DARPP-32 gene polymorphisms (rs12601930C/T, rs879606A/G, and rs3764352A/G) and personality traits as measured by the Tridimensional Personality Questionnaire in 502 healthy Chinese-Han subjects. Of the three polymorphic sites examined, rs12601930C/T was associated with novelty seeking (χ² = 13.06, P = 0.001), while both rs879606A/G and rs3764352A/G were associated with harm avoidance (rs879606: χ² = 7.74, P = 0.021; rs3764352: χ² = 8.53, P = 0.014). There was no significant association between reward dependence scores and DARPP-32 gene polymorphisms. Our results suggest that polymorphisms in the DARPP-32 gene are involved in the biological mechanisms that confer the traits of novelty seeking and harm avoidance.