Personality Trait Of Novelty Seeking Research Articles

Detecting Novelty Seeking From Online Travel Reviews: A Deep Learning Approach

Travel online reviews is important experience related information for understanding an inherent personality trait, novelty seeking (NS), which influences tourism motivation and the choice of tourism destinations. Manual classification of these reviews is challenging due to their high volume and unstructured nature. This paper aims to develop a classification framework and deep learning model to overcome these limitations. A multi-dimensional classification framework was created for NS personality trait that includes four dimensions synthesized from prior literature: relaxation seeking, experience seeking, arousal seeking and boredom alleviation. Based on 30 000 reviews from TripAdvisor we propose a deep learning model using Bidirectional Encoder Representations from Transformers (BERT)- Bidirectional Gated Recurrent Unit (BiGRU) to recognize NS automatically from the reviews. The classifier based on BERT-BiGRU and NS multi-dimensional scales achieved precision and F1 scores of 93.4% and 93.3% respectively, showing that NS personality trait can be relatively accurately recognized. This study also demonstrates that the classifier based on multi-dimensional NS scales can produce satisfactory results using the deep learning model. The findings also indicate that the BERT- BiGRU model achieves the best effect compared to the same kind of deep learning models. Moreover, it proves that personality traits can be automatically identified from travel reviews based on computational techniques. For practical purposes, this study provides a comprehensive classification framework for NS, which can be used in marketing and recommendation systems operating in the tourism industry.

Progress on novelty in tourism: An integration of personality, attitudinal and emotional theoretical foundations

Novelty is often depicted as the essence of travelling and is gaining attention in the tourism literature. However, the understanding of novelty is diverse, with multiple theoretical perspectives and a lack of consensus regarding its definition and conceptualisation. This study integrates different theoretical perspectives and presents an extended analysis of the progress of novelty in tourism, both chronologically and thematically. The findings indicate three thematic clusters categorised based on the core of novelty, its antecedents, and consequences, evolving through different time periods. The results show that the core is mostly based on emotional appraisal attributes, is influenced by novelty-seeking personality traits, and can drive consequences including tourist satisfaction, loyalty, and value. Future research can explore an integrated theoretical perspective based on defining novelty in tourism as an attitudinal belief with varying degrees of valence, extremity, and arousal in the evaluative space, which connects novelty to other relevant antecedents and consequences.

The Cortico-basal-cerebellar Neurocircuit is Linked to Personality Trait of Novelty Seeking

Previous neuroimaging studies have highlighted the role of the prefrontal-subcortical circuits in personality trait of novelty seeking (NS), thought to be mediated by the dopaminergic system. However, it remains largely unknown whether cortico-basal-cerebellar connections, heavily influenced by dopamine, are implicated in this temperament dimension as well. The present study aimed to further investigate the relationship between the NS trait and the cortico-basal-cerebellar pathways by using structural covariance network analysis. Ninety-five healthy female volunteers were included in this work, and NS was assessed with the Temperament and Character Inventory (TCI). Our results showed that NS scores were associated with structural connections between the cerebellum and the cerebral cortex, thalamus, and basal ganglia, substantiating the implication of the cortico-basal-cerebellar circuits in the NS construct. In addition, structural connections between visual and sensorimotor regions were also associated with NS scores, indicating that sensory and motor information processing may contribute to NS-related behaviors. Overall, the current findings may deepen our understanding of brain structural circuits related to this temperament dimension.

Effects of active exploration on novelty-related declarative memory enhancement

Exploration of novel environments has reliably been shown to enhance learning in rodents. More recently, these effects have been replicated in humans using virtual reality: Memory is enhanced after exploration of novel compared to familiar virtual environments. However, exploration of a novel versus familiar environment differs in another aspect. Navigating familiar territory can rely more on habits, while navigating new territory requires active decision-making. This difference in choices could contribute to the positive effects of novelty exploration on memory. In this study, we aimed to investigate this possibility. Participants familiarized with a virtual environment (day 1) and were exposed to this environment again (day 2 or 3) and to a novel environment (day 2 or 3). Participants either actively explored the environments or were passively exposed to the exploration behavior of another participant in virtual reality. After exposure to the environment, participants performed a word-learning task and filled out questionnaires regarding virtual presence and the novelty seeking personality trait. Mixed models suggested that memory performance was higher after participants actively explored versus were passively exposed to a novel environment, while these effects were reversed for a familiar environment. Bayesian statistics provided further weak evidence that memory performance was influenced by the interaction between novelty and exposure type. Taken together, our findings suggest that active exploration may contribute to novelty-induced memory benefits, but future studies need to confirm this finding.

Relationship of Temperament and Character Traits, Emotional Regulation and Perceived Parenting With Self-harming Behaviors in Adolescents

Objectives: The current study aims to provide a structural modeling of self-harm behaviors in adolescents based on their temperament and character traits, emotion regulation strategies, and perceived parenting. Methods: This is a descriptive/correlational study. The study population consists of all high school students (1-3th grade) during 2017-2018 in Tehran, Iran. Of these, 159 with a mean age of 15±0.75 years were selected by using a cluster sampling technique. they were assessed by Temperament and Character Inventory (TCI), Parenting Styles and Dimensions Questionnaire (PSDQ), Cognitive Emotion Regulation Questionnaire (CERQ), and Deliberate Self-Harming Inventory (DSHI). For data analysis, Pearson correlation test and structural equation modeling were conducted in LISREL v. 8.8 and SPSS v. 20 applications. Results: Novelty seeking dimension of TCI and maladaptive cognitive emotion regulation strategies had a direct and positive relationship with self-harming behavior. Although harm avoidance dimension of TCI and authoritarian parenting had no direct effect on self-harming behaviors, they became effective after mediation by maladaptive cognitive emotion regulation strategies. Maladaptive emotion regulation strategies and novelty seeking together were able to predict 22% of the variance in self- harming behavior Conclusion: Novelty seeking personality trait and authoritarian parenting can affect and predict self-harming behaviors of the adolescents.Sirwan Karimi

No association between craving levels, personality traits, and treatment outcomes in patients with methamphetamine use disorder under deferred prosecution status

Objective: Few studies have examined the outcome predictors in methamphetamine (MA) use disorder patients referred from the justice system. Craving and personality trait, such as novelty seeking (NS) and harm avoidance (HA), have important roles in developing and sustaining addiction. Therefore, we investigated whether craving severity and personality traits are correlated with the MA use disorder treatment outcomes in those under the deferred prosecution status. Methods: We measured craving levels and personality traits of NS and HA at the beginning of a one-year treatment program for MA use disorder. We monitored urinary MA/amphetamine results during the one-year treatment program. Multiple linear regressions were used to examine the correlation between craving severity, personality traits, and MA use disorder treatment outcomes. Results: We first enrolled 98 patients, but only 56 patients completed the end-of-treatment assessments. We did not find any association between craving severity, personality traits, and MA treatment outcomes in those populations. But we found that age and percentage of positive urine MA/amphetamine results were significantly related to treatment completion (p ＜ 0.05). Higher percentages of positive urine MA/amphetamine results were also significantly associated with shorter treatment duration (p = 0.01). In addition, positive urine results at baseline were significantly associated with higher percentages of positive urine tests in the following treatment course (p = 0.001). Conclusion: Our study data did not find that craving severity and personality traits were associated treatment outcomes in this special population. But urine MA/amphetamine results were more related with completion of programs. Further studies to evaluate the treatment outcomes and other potential outcome predictors in those were referred from the justice system are needed.

An analysis of genetic association in opioid dependence susceptibility.

Drug addiction is a novelty-seeking personality trait that is associated with the candidate genes OPRD1 (opioid delta receptors), OPRK1 (opioid kappa receptors) and PDYN (prodynorphin). However, associations between single nucleotide polymorphisms (SNPs) rs1042114 (80G>T) of the OPRD1 gene, rs702764 (843 A>G) of the OPRK1 gene, and rs910080 (3' UTR _743T>C), rs1997794 (5' UTR -381A>G) and rs1022563 (3' UTR) of the PDYN gene and novelty seeking remain controversial as reported results have not been reproducible. The goal of this study was to determine the frequencies of SNPs rs1042114, rs702764, rs1997794, rs1022563 and rs910080 in the Malaysian population and to study their association with opioid dependence in Malaysian Malays. A total of 459 Malay male with opioid dependence and 543 healthy male (controls) subjects were included in this study. SNPs were genotyped using the TaqMan SNP genotyping assay. Statistical analysis was performed using Golden Helix SVS software suite to identify the distribution of allele and genotype frequencies, and SNP-SNP interactions were also analysed in this study. SNP rs1042114 in the OPRD1 gene is strongly associated with opiate addiction (P=.0001). In individuals homozygous for this risk allele, the likelihood of opiate addiction is increased by a factor 1.62 (95% confidence interval (CI) 1.412-1.875). Polymorphic alleles at SNP rs702764 of OPRK1 were not associated with opioid dependence. A significant association between opioid dependence and SNP rs910080 of PDYN (P=.0217) was detected, but there was no association for SNPs rs199774 and rs1022563. A significant interaction was also identified between homozygous wild-type genotype TT of rs702764 with the risk genotypes TG/GG of rs1042114 (odds ratio (OR)=2.111 (95% CI 1.227-3.631), P=.0069) and with the risk genotypes GA/AA of rs910080 (OR=1.415 (95% CI 1.04-1.912), P=.0239). The results indicate that SNPs rs1042114 and rs910080 contribute to vulnerability to opioid dependence in the Malaysian Malay population. These results will help us to understand the effect of the SNPs and the SNP-SNP interaction on opioid dependence and may assist in efforts to screen vulnerable individuals and match them with individually tailored prevention and treatment strategies.

Genetic and Environmental Basis of the Relationship Between Dissociative Experiences and Cloninger’s Temperament and Character Dimensions – Pilot Study

Abstract Dissociation is commonly regarded as a disruption in the normally integrated functions of memory, knowledge, affect, sensation or behavior. The present study utilized behavioral genetics’ methodology to investigate genetic and environmental basis of the relationship between dissociation and Cloninger’s temperament and character traits. A sample of 83 monozygotic and 65 dizygotic twins were administered self-report measures which assessed dissociative experiences along with personality dimensions. Significant correlations and high loads of common genetic variance between dissociative experiences and personality traits of novelty seeking, self-directedness, cooperativeness and self-transcendence were identified. Heritability of dissociative experiences was estimated at 62%. The study shows that there exists a considerable amount of genetic variance overlap between dissociation and personality dimensions. It also supports the hypothesis that propensity to dissociate is highly heritable

The Relation ofToxoplasmaInfection and Sexual Attraction to Fear, Danger, Pain, and Submissiveness

Behavioral patterns, including sexual behavioral patterns, are usually understood as biological adaptations increasing the fitness of their carriers. Many parasites, so-called manipulators, are known to induce changes in the behavior of their hosts to increase their own fitness. Such changes are also induced by a parasite of cats, Toxoplasma gondii. The most remarkable change is the fatal attraction phenomenon, the switch of infected mice’s and rat’s native fear of the smell of cats toward an attraction to this smell. The stimuli that activate fear-related circuits in healthy rodents start to also activate sex-related circuits in the infected animals. An analogy of the fatal attraction phenomenon has also been observed in infected humans. Therefore, we tried to test a hypothesis that sexual arousal by fear-, violence-, and danger-related stimuli occurs more frequently in Toxoplasma-infected subjects. A cross-sectional cohort study performed on 36,564 subjects (5,087 Toxoplasma free and 741 Toxoplasma infected) showed that infected and noninfected subjects differ in their sexual behavior, fantasies, and preferences when age, health, and the size of the place where they spent childhood were controlled ( F(24, 3719) = 2.800, p < .0001). In agreement with our a priori hypothesis, infected subjects are more often aroused by their own fear, danger, and sexual submission although they practice more conventional sexual activities than Toxoplasma-free subjects. We suggest that the later changes can be related to a decrease in the personality trait of novelty seeking in infected subjects, which is potentially a side effect of increased concentration of dopamine in their brain.

Compulsive Buying Behavior: Clinical Comparison with Other Behavioral Addictions.

Compulsive buying behavior (CBB) has been recognized as a prevalent mental health disorder, yet its categorization into classification systems remains unsettled. The objective of this study was to assess the sociodemographic and clinic variables related to the CBB phenotype compared to other behavioral addictions. Three thousand three hundred and twenty four treatment-seeking patients were classified in five groups: CBB, sexual addiction, Internet gaming disorder, Internet addiction, and gambling disorder. CBB was characterized by a higher proportion of women, higher levels of psychopathology, and higher levels in the personality traits of novelty seeking, harm avoidance, reward dependence, persistence, and cooperativeness compared to other behavioral addictions. Results outline the heterogeneity in the clinical profiles of patients diagnosed with different behavioral addiction subtypes and shed new light on the primary mechanisms of CBB.

The cortical surface area of the insula mediates the effect of DBH rs7040170 on novelty seeking

Novelty seeking (NS) is a personality trait important for adaptive functioning, but an excessive level of NS has been linked to psychiatric disorders such as ADHD and substance abuse. Previous research has investigated separately the neural and genetic bases of the NS trait, but results were mixed and neural and genetic bases have yet to be examined within the same study. In this study, we examined the interrelationships among the dopamine beta-hydroxylase (DBH) gene, brain structure, and the NS trait in 359 healthy Han Chinese subjects. We focused on the DBH gene because it encodes a key enzyme for dopamine metabolism, NS is believed to be related to the dopaminergic system and has been reported associated with DBH variation. Results showed a significant positive association between the cortical surface area of the left insula and NS score. Furthermore, the DBH genetic polymorphism at the SNP rs7040170 was strongly associated with both the surface area of the left insula and NS score, with G carriers having a larger left insula surface area and a higher NS score than AA homozygotes. Subsequent path analysis suggested that the insula partially mediated the association between the DBH gene and the NS trait. Our data provided the first evidence for the involvement of the insula in the dopamine–NS relationship. Future studies of molecular mechanisms underlying the NS personality trait and related psychiatric disorders should consider the mediation effect of the neural structure.

The dopamine transporter gene may not contribute to susceptibility and the specific personality traits of amphetamine dependence

BackgroundA substantial amount of evidence suggests that dysfunction of the dopamine transporter may be involved in the pathophysiology of amphetamine dependence (AD). The aim of this study was to examine whether the dopamine transporter gene (DAT1, SLC6A3) is associated with development of AD and whether this gene influences personality traits in patients with AD. MethodsEighteen polymorphisms of the DAT1 gene were analyzed in a case-control study that included 909 Han Chinese men (568 patients with AD and 341 control subjects). The patients fulfilled the DSM-IV-TR criteria for AD. The Tridimensional Personality Questionnaire (TPQ) was used to assess personality traits and to examine the association between these traits and DAT1 gene variants. ResultsA weak association was found between the rs27072 polymorphism and development of AD, but these borderline associations were unconfirmed by logistic regression and haplotype analysis. Although harm avoidance and novelty seeking scores were significantly higher in patients than in controls, DAT1 polymorphisms did not influence these scores. ConclusionsThis study suggests that high harm avoidance and novelty seeking personality traits may be a risk factor for the development of AD. However, the DAT1 gene may not contribute to AD susceptibility and specific personality traits observed in AD among Han Chinese men.

Do Parkinson's Disease Patients Have Deficits in Sequential Sampling Tasks?

The aim of this study was to assess the neuropsychological behavior of Parkinson's disease (PD) patients with addictive behaviors. Characteristically, these patients have younger onset of PD, higher novelty-seeking personality traits, jump to conclusions, and often make irrational choices. We assessed whether PD patients with and without addictive behaviors have deficits in a sequential sampling task, often called the secretary problem. In this task, participants needed to pick the best out of multiple offers. Critically, once participants rejected a deal, this option became unavailable. Thus, decisions needed to be balanced not to stop too soon or sample for too long and miss the best deal. We tested 13 PD patients with and 13 patients without addictive behaviors. Results were compared to healthy volunteers. We found that all patients declined fewer options before committing to a deal. There was, however, no difference between the two patient groups. Furthermore, there was no difference in overall choice rank between patients and controls. These results suggest that, compared to controls, PD patients gather less evidence before committing to an offer, but have no deficits in recognizing the best deal out of many options, regardless of whether or not they have addictive behaviors.

Higher sensitivity to the conditioned rewarding effects of cocaine and MDMA in High-Novelty-Seekers mice exposed to a cocaine binge during adolescence.

Exposure to drugs during adolescence can induce alterations in the central nervous system. The novelty-seeking personality trait influences differences observed among individuals exposed to drugs of abuse. Long-term effects of intensive pre-treatment with cocaine during adolescence or adulthood were evaluated in High- and Low-Novelty Seeker (HNS and LNS) mice. It was hypothesized that a cocaine binge during adolescence would increase sensitivity to the rewarding effects of cocaine and MDMA, especially in HNS animals, and modify the spontaneous behaviour of adult animals. Adolescent (PND 33) and adult (PND 60) mice were identified as HNS or LNS according to their performance in the hole-board test. Subsequently, they received pre-treatment with cocaine (three injections per day of an increasing dose for 10 days) or saline. Three weeks later, the mice performed the hole-board, elevated plus maze, spontaneous locomotor activity and cocaine- (1 mg/kg) or MDMA- (1.25 mg/kg) induced conditioning place preference (CPP) tests. In another set of mice, the effects of pre-treatment of cocaine during adulthood on MDMA- or cocaine-induced CPP were also evaluated 3 weeks later. Only HNS mice treated with cocaine during adolescence acquired MDMA- or cocaine-induced CPP in adulthood. Moreover, pre-exposure to cocaine during adolescence caused subsequent behavioural alterations, including reduced exploratory behaviour and increased locomotor reactivity. Cocaine binge administration during adolescence induces a higher sensitivity to the rewarding effects of MDMA and cocaine in HNS mice in adulthood. This may explain the greater vulnerability often seen among individuals exposed early in life to drugs of abuse.

Role of personality traits in cocaine craving throughout an outpatient psychosocial treatment program

Cocaine dependence is a major international public health concern. Its chronically relapsing nature is possibly related to craving intensity, which can be influenced by diverse biological and psychological aspects. This study aimed to evaluate the role of different personality traits in craving measured throughout a psychosocial treatment program. The sample comprised 66 cocaine-dependent outpatients who were enrolled in an individual and manualized cognitive-behavioral therapy program. The influence of personality traits on craving intensity, frequency, and duration was analyzed using a generalized estimating equations model with an autoregressive correlation structure. Craving varied during treatment. The personality traits of novelty seeking, reward dependence, and harm avoidance interacted with craving intensity, and the personality trait of persistence interacted with craving duration throughout the treatment period. Furthermore, there were significant interactions between drug use and craving intensity, and between different routes of administration and craving intensity. Participants who used cocaine/crack while in treatment and concurrent users of crack (i.e., freebase) cocaine and powder cocaine also had a higher craving intensity. The extent of craving variation can depend on certain personality styles. This study shows that craving is influenced by personality traits, and this may presumably change clinical expression involved in disease.

Neurotensin Receptor 1 Gene Polymorphisms Are Associated with Personality Traits in Healthy Chinese Individuals

Aims: Neurotensin receptor 1 (NTR1) is a neurotensin (NT) receptor subtype with a high affinity for NT. NT and NTR1 signaling are involved in modulating the dopamine system. Individual variations in the dopamine system have been demonstrated to determine certain dimensions of personality, but no studies have thus far investigated the involvement of the NTR1 in the biological determination of personality. We therefore examined this link in a Chinese Han population. Methods: We genotyped 3 single nucleotide polymorphisms (SNPs) (rs6090453C/G, rs6011914C/G, and rs2427422A/G) of the NTR1 gene and collected the data about the personality traits of novelty seeking (NS), harm avoidance (HA), and reward dependence (RD), as well as their subscales (measured by the Tridimensional Personality Questionnaire), in 575 healthy Chinese Han subjects. Then we examined the association between the 3 NTR1 gene polymorphisms and each personality trait. Results: There were significant differences in the HA2, HA3 and RD1 scores between rs6090453C/G genotypes (F = 3.425, 5.651, 4.054, p = 0.033, 0.004, 0.018, respectively), in the HA2 and total RD scores between rs6011914C/G genotypes (F = 4.080, 3.712, p = 0.017, 0.025, respectively), and in the total RD (χ² = 7.301, p = 0.026) and RD3 (F = 4.119, p = 0.017) scores between the rs2427422A/G genotypes. There were significant male-specific differences in the RD1 scores between the rs6090453C/G genotypes (F = 3.334, p = 0.037), in the total HA (F = 3.043, p = 0.049), HA2 (F = 4.472, p = 0.012) and RD3 (χ² = 6.997, p = 0.030) scores between the rs6011914C/G genotypes, and in the HA2 (F = 3.177, p = 0.043), total RD (χ² = 7.032, p = 0.030), and RD3 (F = 4.563, p = 0.011) scores between the rs2427422A/G genotypes. We also demonstrated a significant female-specific difference in the total RD scores between the rs6011914C/G genotypes (F = 3.677, p = 0.026). There was no significant difference in the total NS and subscale scores between the genotypes of all 3 SNPs (all p > 0.05). Conclusions: The variations in the NTR1 gene were involved in the biological mechanisms of HA and RD personality traits; however, the effect is influenced by gender.

The boundaries of the internalizing and externalizing genetic spectra in men and women

The distribution and co-morbidity of common psychiatric disorders can be largely explained as manifestations of two broad psychopathological spectra of internalizing and externalizing disorders. Twin studies suggest that these spectra arise from genetic factors. Structural equation twin modeling was applied to interview and questionnaire data on personality traits and lifetime psychiatric disorders on more than 5300 members of male-male (MM) and female-female (FF) twin pairs. The best-fitting models for both the externalizing and internalizing spectra differed significantly in males and females. In males, the externalizing genetic common factor was best indexed by four disorders in the following order: antisocial personality disorder (ASPD), drug abuse/dependence (DAD), alcohol abuse dependence (AAD) and conduct disorder (CD). In females, the four disorders most closely related to the externalizing common factor were, in order: DAD, AAD, nicotine dependence (ND) and ASPD. Personality traits of novelty seeking (NS) and extraversion (E) better indexed the genetic externalizing spectrum in females than in males. In both males and females, major depression (MD) and generalized anxiety disorder (GAD) best indexed the genetic internalizing common factor. Panic disorder (PD) and agoraphobia (AgP) better reflected the internalizing genetic common factor in women, and neuroticism (N) in men. Genetic correlations between the two spectra were estimated at + 0.53 in males and + 0.52 in females. The disorders that optimally index the genetic liability to externalizing and internalizing disorders in the general population differ meaningfully in men and women. In both sexes, these genetic spectra are better assessed by psychiatric disorders than by personality traits.

Impulse Control Disorders in Parkinson’s Disease: A Review

The development of Impulse Control Disorders (ICDs) in Parkinson’s disease (PD) is a recognised iatrogenic complication associated with the use of dopamine agonists. The prevalence of ICDs has been reported to be as high as 14% in studies conducted in Europe and North America. Early case reports and recent large-scale studies have shown that clinical features associated with the development of PD-related ICDs include novelty-seeking personality traits, early onset PD and a past history of psychiatric conditions. More recent studies have also suggested that ICDs may be associated with deep brain stimulation and dyskinesias. Moreover, there is heterogeneity in the clinical features associated with the range of ICDs, with studies pointing out that compulsive sexual behaviours and binge eating have fewer clinical features in common than compulsive buying and pathological gambling. The recent increase in the number of functional neuroimaging studies on patients with PD and ICDs, particularly those with pathological gambling, has provided a unique opportunity to understand the neurobiology of the disorder, and has indicated an abnormality in the meso-limbic dopaminergic pathways. Further studies directly comparing ICD sufferers with and without PD will provide valuable knowledge to aid in the management of both patient groups. This review will provide a clinical overview of impulse control behaviours in PD, including both commonly reported ICDs and other related impulsive-compulsive behaviours observed in PD. Keywords: Dopamine dysregulation syndrome, Binge eating, Compulsive buying, Compulsive sexual behaviour, Functional imaging, Impulse control disorder, Parkinson disease, Pathological gambling, Phenomenology, Compulsive Sexual Behaviour

Association between the dopamine D2 receptor (DRD2) polymorphism and the personality traits of healthy Japanese participants

Dopamine neurotransmitter systems have been associated with reward-related and novelty-seeking personality traits. We investigated the possible relationship between the personality traits measured by the Temperament and Character Inventory (TCI) and the TaqI A and -141C Ins/Del polymorphisms in the dopamine D2 receptor gene (DRD2). The sample consisted of 1084 healthy Japanese medical students and medical staff (age=29.0±9.7 years), each of whom completed the TCI. Their genomic DNA was isolated from whole blood and genotyped using the TaqMan allele-specific assay method. The associations between gene polymorphisms and the scores for TCI were statistically analyzed by one-way analysis of covariance (ANCOVA) adjusting age. Males and females were analyzed separately. Epstatis was assesses using two-way ANCOVA between the DRD2 and ANKK1 genes. Men with the Ins/Del genotype of the -141C Ins/Del polymorphism had significantly higher self-directedness scores than those with the Ins/Ins genotype (p=0.021). None of the TCI scores differed among women with regard to the three genotype groups of the -141C Ins/Del polymorphism. The DRD2/ANKK1 Taq1 A polymorphism did not affect any TCI factor for either men or women. An epistatic analysis did not reveal main effects of the two genes with regard to TCI scores, but an ANKK1×DRD2 interaction significantly predicted TCI scores. These findings suggest the possibility that the -141C Ins/Del polymorphism and the DRD2/ANKK1 Taq1 A polymorphism are not strongly linked to personality traits directly, but influences them under the interaction between the DRD2 and ANKK1 genes.

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.