Relation among dopamine D(2) receptor binding, obesity and personality in normal human subjects

Molecular Imaging of Central Dopamine in Obesity: A Qualitative Review across Substrates and Radiotracers

Dopamine is a neurotransmitter that plays a crucial role in adaptive behavior. A wealth of studies suggests obesity-related alterations in the central dopamine system. The most direct evidence for such differences in humans comes from molecular neuroimaging studies using positron emission tomography (PET) and single-photon emission computed tomography (SPECT). The aim of the current review is to give a comprehensive overview of molecular neuroimaging studies that investigated the relation between BMI or weight status and any dopamine target in the striatal and midbrain regions of the human brain. A structured literature search was performed and a summary of the extracted findings are presented for each of the four available domains: (1) D2/D3 receptors, (2) dopamine release, (3) dopamine synthesis, and (4) dopamine transporters. Recent proposals of a nonlinear relationship between severity of obesity and dopamine imbalances are described while integrating findings within and across domains, after which limitations of the review are discussed. We conclude that despite many observed associations between obesity and substrates of the dopamine system in humans, it is unlikely that obesity can be traced back to a single dopaminergic cause or consequence. For effective personalized prevention and treatment of obesity, it will be crucial to identify possible dopamine (and non-dopamine) profiles and their functional characteristics.

Personality traits and BMI trends over three years in Japanese university students

In Europe and America, associations between personality traits and body-mass index (BMI) have been reported. However, in Japan, the association between personality traits and BMI (i.e., thinness and obesity) has not been well studied. In this study, we investigated the relationship between Temperament and Character Inventory (TCI) personality traits and changes in BMI status among Japanese students during their university attendance. We measured the height and weight of 5,340 students in a Japanese university during annual medical checkups and calculated their BMI. The students' personality traits were measured using the short Japanese version of the TCI at university admission. The participants were divided into seven groups based on how BMI changed from the first year to the fourth year at university. In men, compared to the group that maintained normal BMI status (N = 2,189) over time (i.e., the control group), the group that maintained thinness status (N = 226) were lower in Reward Dependence, and the group whose status improved from thinness to normal (N = 117) were higher in Harm Avoidance. In women, compared with the control group (N = 1,510), the group that maintained thinness status (N = 302) was lower in Novelty Seeking, and the group whose status worsened from normal to thinness (N = 127) was higher in Harm Avoidance. Weak associations were found between thinness and TCI personality traits among Japanese university students. Further elaboration of the relationship between obesity or thinness and personality traits may help to provide effective preventive interventions in these areas.

Relations Between Sleep and Temperament in Preschool Children With ADHD

Objective: The objective of this study was to assess the links between temperament and sleep in a group of preschoolers with ADHD. Method: Twenty-five ADHD (M = 5.37 years, SD = 1.09) and 22 typically developing (TD; M = 5.10, SD = 1.18) preschoolers participated in the study. Sleep was assessed with the Sleep Disturbance Scale and wrist actigraphy. The Preschool Temperament and Character Inventory (PsTCI) was used to evaluate the child temperament. Results: ADHD children showed a temperamental profile characterized by higher novelty seeking, lower persistence, self-directness, and cooperativeness and marginally lower harm avoidance (HA) compared with controls. HA was associated negatively to wakefulness after sleep onset and sleep fragmentation and positively with sleep efficiency and sleep time. Reward dependence was negatively associated with wake episode length. Conclusion: Sleep and temperament are correlated in preschoolers with ADHD and temperament might represent an intermediate endophenotype underlying the relation between ADHD and sleep disorders.

Associations Among Monoamine Neurotransmitter Pathways, Personality Traits, and Major Depressive Disorder

Major depressive disorder (MDD) is a complex psychiatric disease requiring multidisciplinary approaches to identify specific risk factors and establish more efficacious treatment strategies. Although the etiology and pathophysiology of MDD are not clear until these days, it is acknowledged that they are almost certainly multifactorial and comprehensive. Monoamine neurotransmitter system dysfunction and specific personality traits are independent risk factors for depression and suicide. These factors also demonstrate complex interactions that influence MDD pathogenesis and symptom expression. In this review, we assess these relationships with the aim of providing a reference for the development of precision medicine.

Elevated Dopamine D2/3 Receptor Availability in Obese Individuals: A PET Imaging Study with [11C](+)PHNO

Most prior work with positron emission tomography (PET) dopamine subtype 2/3 receptor (D_2/3R) non-selective antagonist tracers suggests that obese (OB) individuals exhibit lower D_2/3Rs when compared with normal weight (NW) individuals. A D₃-preferring D_2/3R agonist tracer, [¹¹C](+)PHNO, has demonstrated that body mass index (BMI) was positively associated with D_2/3R availability within striatal reward regions. To date, OB individuals have not been studied with [¹¹C](+)PHNO. We assessed D_2/3R availability in striatal and extrastriatal reward regions in 14 OB and 14 age- and gender-matched NW individuals with [¹¹C](+)PHNO PET utilizing a high-resolution research tomograph. Additionally, in regions where group D_2/3R differences were observed, secondary analyses of 42 individuals that constituted an overweight cohort was done to study the linear association between BMI and D_2/3R availability in those respective regions. A group-by-brain region interaction effect (F_{7, 182}=2.08, p=0.047) was observed. Post hoc analyses revealed that OB individuals exhibited higher tracer binding in D₃-rich regions: the substantia nigra/ventral tegmental area (SN/VTA) (+20%; p=0.02), ventral striatum (VST) (+14%; p<0.01), and pallidum (+11%; p=0.02). BMI was also positively associated with D_2/3R availability in the SN/VTA (r=0.34, p=0.03), VST (r=0.36, p=0.02), and pallidum (r=0.30, p=0.05) across all subjects. These data suggest that individuals who are obese have higher D_2/3R availability in brain reward regions densely populated with D₃Rs, potentially identifying a novel pharmacologic target for the treatment of obesity.

Associations between dopamine D2 receptor availability and BMI depend on age

OBJECTIVE

The dopamine D2/3 receptor subtypes (DRD2/3) are the most widely studied neurotransmitter biomarker in research on obesity, but results to date have been inconsistent, have typically involved small samples, and have rarely accounted for subjects' ages despite the large impact of age on DRD2/3 levels. We aimed to clarify the relation between DRD2/3 availability and BMI by examining this association in a large sample of subjects with BMI spanning the continuum from underweight to extremely obese.

SUBJECTS

130 healthy subjects between 18 and 81years old underwent PET with [18F]fallypride, a high affinity DRD2/3 ligand.

RESULTS

As expected, DRD2/3 availability declined with age. Critically, age significantly interacted with DRD2/3 availability in predicting BMI in the midbrain and striatal regions (caudate, putamen, and ventral striatum). Among subjects under 30years old, BMI was not associated with DRD2/3 availability. By contrast, among subjects over 30years old, BMI was positively associated with DRD2/3 availability in the midbrain, putamen, and ventral striatum.

CONCLUSION

The present results are incompatible with the prominent dopaminergic hypofunction hypothesis that proposes that a reduction in DRD2/3 availability is associated with increased BMI, and highlights the importance of age in assessing correlates of DRD2/3 function.

Cloninger's temperament and character traits in medical students of Korea with problem eating behaviors

BACKGROUND AND OBJECTIVE

The personality profiles of patients with eating disorder have been extensively investigated, but those of people in the general population with eating behavior problems need to be evaluated to assess the relationship between personality, health behavior and level of overall well-being in non-clinical samples.

DESIGN

Temperament and character traits, reasons for over-eating, and the negative influence of functional dyspepsia on quality of life were measured by the Temperament and Character Inventory (TCI), Dutch Eating Behavior Questionnaire (DEBQ), and Functional Dyspepsia Quality of Life (FDQOL) inventory, respectively, in 199 Korean medical students. The associations among TCI, FDQOL, DEBQ and body mass index (BMI) were examined by correlational analysis. Multiple regression analysis was carried out to measure how well personality (TCI) accounted for patterns of overeating (DEBQ) and impaired quality of life from functional dyspepsia (FDQOL).

RESULTS

Individual differences in personality (especially harm-avoidance, self-transcendence, and self-directedness) were weakly associated with overeating and impaired quality of life from functional dyspepsia. Gender, social desirability and body mass index also played important roles in predicting eating behavior problems in the nonclinical population.

DISCUSSION AND CONCLUSION

We found that the personality traits observed in clinical patients with eating disorders are also found in people with eating behavior problems in the nonclinical population of Korea. The ways that personality traits affect eating behaviors were discussed along with recommendations for future studies in light of the limitations of available data.

Mean diffusivity of globus pallidus associated with verbal creativity measured by divergent thinking and creativity-related temperaments in young healthy adults

Recent investigations revealed mean diffusivity (MD) in gray matter and white matter areas is correlated with individual cognitive differences in healthy subjects and show unique properties and sensitivity that other neuroimaging tools donot have. In this study, we tested the hypothesis that the MD in the dopaminergic system is associated with individual differences in verbal creativity measured by divergent thinking (VCDT) and novelty seeking based on prior studies suggesting associations between these and dopaminergic functions. We examined this issue in a large sample of right‐handed healthy young adults. We used analyses of MD and a psychological measure of VCDT, as well as personality measures of the Temperament and Character Inventory (TCI). Our results revealed associations between higher VCDT and lower MD in the bilateral globus pallidus. Furthermore, not only higher novelty seeking, but also lower harm avoidance, higher self‐directedness, and higher self‐transcendence were robustly associated with lower MD in the right globus pallidus, whereas higher persistence was associated with lower MD in the left globus pallidus. These personality variables were also associated with VCDT. The globus pallidus receives the dopaminergic input from the substantia nigra and plays a key role in motivation which is critically linked to dopamine. These results suggested the MD in the globus pallidus, underlie the association between VCDT and multiple personalities in TCI including novelty seeking. Hum Brain Mapp 36:1808–1827, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

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 (χ(2) = 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 (χ(2) = 6.997, p = 0.030) scores between the rs6011914C/G genotypes, and in the HA2 (F = 3.177, p = 0.043), total RD (χ(2) = 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.

Personality traits and obesity: a systematic review

Based on a bio-social-ecological systems model of the development and maintenance of obesity, there has been in the last few years a growing research interest in the association of obesity and personality traits. The aim of the present review was a comprehensive and critical evaluation of the existing literature taking into account the methodological quality of studies to enhance our understanding of personality traits associated with body weight, the development of overweight and obesity as well as the effectiveness of weight loss interventions including bariatric surgery. Personality traits play an important role both as risk as well as protective factors in the development of overweight and obesity. While thus in particular 'neuroticism', 'impulsivity' and 'sensitivity to reward' appear as risk factors, 'conscientiousness' and 'self-control' have been shown to have a protective function in relation to weight gain. Conscientiousness is a measure of regulation of internal urges and self-discipline, and may thus provide a potential source of control over impulsive reward-oriented behaviour. The results of the present review suggest that, within the context of therapeutic weight reduction measures, it is meaningful to identify subgroups of patients for whom specific treatment options need to be developed, such as measures for strengthening self-control skills.

Evaluation of temperament and character features as risk factors for depressive symptoms in patients with restless legs syndrome

BACKGROUND AND PURPOSE

Restless legs syndrome (RLS) is a common sleep-related movement disorder that is frequently associated with psychological disturbances. Personality traits are of considerable importance with respect to coping with chronic illness and disease vulnerability. This study assessed the temperament and character traits of RLS patients using an approach that involves the psychobiological model of personality.

METHODS

The personality features of 65 newly diagnosed and untreated RLS patients with no neurological or psychiatric diseases and 109 healthy controls were determined using the Temperament and Character Inventory and compared using covariance analyses. The International RLS Study Group Severity Scale was used to assess the severity of the RLS symptoms, and the Beck Depression Inventory was used to assess the presence and severity of depressive symptoms.

RESULTS

RLS patients scored significantly higher than healthy controls on the temperament dimension of harm avoidance (HA, p=0.02) and significantly lower on self-directedness (SD, p=0.001). No significant difference was observed in terms of the temperament dimension of novelty seeking (p=0.435). HA scores were significantly correlated with the BDI score but not with the RLS severity or duration.

CONCLUSIONS

High HA and low SD scores are the main characterizing personality features of RLS patients. These personality dimensions may be among the factors predisposing patients to development of the depressive symptoms that are frequently associated with RLS.

Personality characteristics and body image in obese individuals

INTRODUCTION

The aim of this study was to determine the personality characteristics of obese and morbidly obese individuals with no psychiatric disorder and the correlation between these characteristics and body image and self-esteem.

METHODS

Sixty-nine obese individuals and 69 healthy controls, matched in age, sex and marital status, were included in the study. Psychiatric disorders were excluded for all participants using SCID-I and II. Obese and healthy volunteers were compared in terms of body image, self-esteem and personality characteristics.

RESULTS

TCI harm avoidance scores were higher in obese individuals compared to healthy controls. Harm avoidance scores were also higher in individuals with morbid obesity compared to non-morbid individuals, while self-directedness and persistence scores were lower. Body image dissatisfaction was higher in obese individuals. There was a negative correlation in obese individuals between body image and self-esteem scale scores and harm avoidance scores, and a positive correlation with self-directedness scores.

DISCUSSION

An elevated harm avoidance temperament characteristic may be correlated with obesity. Furthermore, high harm avoidance, low self-directedness and low persistence may be significant personality characteristics in a process leading to morbid obesity. In addition, harm avoidance temperament and self-directedness personality characteristics may be correlated with body image dissatisfaction and self-esteem in obese individuals.

Harm avoidance is associated with progression of parkinsonism in community-dwelling older adults: a prospective cohort study

Background

We tested the hypothesis that harm avoidance, a trait associated with behavioral inhibition, is associated with the rate of change in parkinsonism in older adults.

Methods

At baseline harm avoidance was assessed with a standard self-report instrument in 969 older people without dementia participating in the Rush Memory and Aging Project, a longitudinal community-based cohort study. Parkinsonism was assessed annually with a modified version of the motor section of the Unified Parkinson’s Disease Rating Scale (mUPDRS).

Results

Average follow-up was 5 years. A linear mixed-effects model controlling for age, sex and education showed that for an average participant (female, 80 years old at baseline, with 14 years of education and a harm avoidance score of 10), the overall severity of parkinsonism increased by about 0.05 unit/ year (Estimate, 0.054, S.E., 0.007, p <0.001) and that the level of harm avoidance was associated with the progression of parkinsonism (Estimate, 0.004, S.E., 0.001, p <0.001). Thus, for an average participant, every 6 point (~1 SD) increase in harm avoidance score at baseline, the rate of progression of parkinsonism increased about 50% compared to an individual with an average harm avoidance score. This amount of change in parkinsonism over the course of the study was associated with about a 5% increased risk of death. The association between harm avoidance and progression of parkinsonism persisted when controlling for cognitive function, depressive symptoms, loneliness, neuroticism, late-life cognitive, social and physical activities and chronic health conditions.

Conclusion

A higher level of the harm avoidance trait is associated with a more rapid progression of parkinsonism in older adults.

Dopamine D(2/3) receptor availability and human cognitive impulsivity: a high-resolution positron emission tomography imaging study with [¹¹C]raclopride

OBJECTIVE

Human impulsivity is a complex multidimensional construct encompassing cognitive, emotional, and behavioural aspects. Previous animal studies have suggested that striatal dopamine receptors play a critical role in impulsivity. In this study, we investigated the relationship between self-reported impulsiveness and dopamine D(2/3) receptor availability in striatal subdivisions in healthy subjects using high-resolution positron emission tomography (PET) with [11C]raclopride.

METHODS

Twenty-one participants completed 3-T magnetic resonance imaging and high-resolution PET scans with [11C]raclopride. The trait of impulsiveness was measured using the Barratt Impulsiveness Scale (BIS-11). Partial correlation analysis was performed between BIS-11 scores and D(2/3) receptor availability in striatal subregions, controlling for the confounding effects of temperament characteristics that are conceptually or empirically related to dopamine, which were measured by the Temperament and Character Inventory.

RESULTS

The analysis revealed that the non-planning (p = 0.004) and attentional (p = 0.007) impulsiveness subscale scores on the BIS-11 had significant positive correlations with D(2/3) receptor availability in the pre-commissural dorsal caudate. There was a tendency towards positive correlation between non-planning impulsiveness score and D(2/3) receptor availability in the post-commissural caudate.

CONCLUSION

These results suggest that cognitive subtrait of impulsivity is associated with D(2/3) receptor availability in the associative striatum that plays a critical role in cognitive processes involving attention to detail, judgement of alternative outcomes, and inhibitory control.

A positive relationship between harm avoidance and brain nicotinic acetylcholine receptor availability

Prior research indicates that disturbance of cholinergic neurotransmission reduces anxiety, leading to the hypothesis that people with heightened cholinergic function have a greater tendency toward anxiety-like and/or harm-avoidant behavior. We sought to determine if people with elevated levels of harm avoidance (HA), a dimension of temperament from the Temperament and Character Inventory (TCI), have high α4β2* nicotinic acetylcholine receptor (nAChR) availability. Healthy adults (n=105; 47 non-smokers and 58 smokers) underwent bolus-plus-continuous infusion positron emission tomography (PET) scanning using the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (abbreviated as 2-FA). During the uptake period of 2-FA, participants completed the TCI. The central study analysis revealed a significant association between total HA and mean nAChR availability, with higher total HA scores being linked with greater nAChR availability. In examining HA subscales, both 'Fear of Uncertainty' and 'Fatigability' were significant, based on higher levels of these characteristics being associated with greater nAChR availabilities. This study adds to a growing body of knowledge concerning the biological basis of personality and may prove useful in understanding the pathophysiology of psychiatric disorders (such as anxiety disorders) that have similar characteristics to HA. Study findings may indicate that heightened cholinergic neurotransmission is associated with increased anxiety-like traits.

The dopamine transporter gene possibly affects personality traits in patients with early-onset major depressive disorder

OBJECTIVE

Comorbid personality pathologies may affect the outcome of patients with major depression (MD). The dopamine transporter gene DAT1 (SLC6A3) has been suggested to play a role in both depression and specific personality traits. The aim of this study was to assess five polymorphisms of the DAT1 gene (rs2550948, rs2975226, rs6347, rs27072, and 3'-VNTR) to determine whether this gene influences personality traits in patients with MD or its subgroups.

METHODS

The DAT1 polymorphisms were analysed in 463 unrelated Han Chinese MD patients. The personality traits, novelty seeking (NS), and harm avoidance (HA), were examined using the Tridimensional Personality Questionnaire. The patients were also divided into four clinical subgroups on the basis of differences in their sex (male or female) and age at disease onset (early or late).

RESULTS

There was no association between the DAT1 gene and either NS or HA in the total MD sample or in the sex-based subgroups. However, early-onset MD patients with the G/G genotype of rs2550948 and the T/T genotype of rs2975226 had lower NS scores than did patients with the other genotypes (p corrected = 0.05 for rs2550948 and p corrected = 0.005 for rs2975226).

CONCLUSION

Our study suggests that DAT1 promoter variants possibly influence specific personality traits in the early-onset subgroup of depressed patients in the Han Chinese population. Further prospective cohort studies are required to verify our preliminary finding and to confirm the effects of personality susceptibility on long-term disease outcomes.

Burnout and behavior-related health risk factors: results from the population-based Finnish Health 2000 study

OBJECTIVE

To explore the relationship between burnout and behavior-related health risk factors.

METHODS

We collected data from a population-based sample (n = 3264) through interviews, questionnaires, and health examinations. Burnout was assessed using the Maslach Burnout Inventory-General Survey. Smoking, alcohol consumption, and leisure-time physical activity were self-reported. Obesity was based on measurements at screening.

RESULTS

Burnout and exhaustion were associated with a higher likelihood of risk factors. More specifically, burnout syndrome was related to low physical activity and obesity, exhaustion dimension to low physical activity and heavy drinking, cynicism dimension to low physical activity, and diminished professional efficacy to low physical activity, obesity, and lower likelihood of heavy drinking.

CONCLUSIONS

Improving working conditions and psychoeducation on recommended ways of coping and recovery could help to prevent negative health consequences of chronic work stress.

Mesomorphy correlates with experiential cognitive style

The purpose of this study was to test for a relationship between mesomorphy and experiential cognitive style (S. Epstein, 1994) in a sample of university students (30 women and 24 men). Anthropometric somatotypes were obtained using the Heath-Carter procedure (J. E. L. Carter, 2002). Experiential cognitive style was operationalized as scores on the experiential scale of the Rational Experiential Inventory for Adolescents (A. D. Marks, D. W. Hine, R. L. Blore, & W. J. Phillips, 2008). Nonparametric bootstrap correlations were calculated using 80% confidence intervals. There were significant correlations between mesomorphy and experiential cognitive style for men (r(s) = .33) and women (r(s) = .25). For men, experiential cognitive style was also correlated with endomorphy (r(s) = .39) and ectomorphy (rs = -.48).

Dopamine D2/D3 receptor availability and venturesomeness

The construct of impulsivity is considered as a major trait of personality. There is growing evidence that the mesolimbic dopamine system plays an important role in the modulation of impulsivity and venturesomeness, the two key components within the impulsivity-construct. The aim of the present study was to explore an association between trait impulsivity measured with self-assessment and the dopaminergic neurotransmission as measured by positron emission tomography (PET) in a cohort of healthy male subjects. In vivo D2/D3 receptor availability was determined with [(18)F]fallypride PET in 18 non-smoking healthy subjects. The character trait impulsivity was measured using the Impulsiveness-Venturesomeness-Empathy questionnaire (I7). Image processing and statistical analysis was performed on a voxel-by-voxel basis using statistical parametric mapping (SPM) software. The I7 subscale venturesomeness correlated positively with the D2/D3 receptor availability within the left temporal cortex and the thalamus. Measures on the I7 subscale impulsiveness and empathy did not correlate with the D2/D3 receptor availability in any brain region investigated. Our results suggest the involvement of extrastriatal dopaminergic neurotransmission in venturesomeness, a component of impulsivity.

Frontostriatal response to set switching is moderated by reward sensitivity

The reinforcement sensitivity theory (RST) relates individual differences in reward sensitivity to the activation of the behavioral approach system (BAS). Dopamine-related brain structures have been repeatedly associated with reward processing, but also with cognitive processes such as task switching. In the present study, we examined the association between reward sensitivity and the event-related fMRI BOLD response with set switching in 31 males. As expected, the right inferior frontal cortex (rIFG) and the striatum (i.e. the left putamen) were involved in set-switching activity for the overall sample. Interindividual differences in Gray's reward sensitivity were related to stronger activity in the rIFG and the ventral striatum. Thus, trait reward sensitivity contributed to the modulation of brain responsiveness in set-switching tasks. Having considered previous research, we propose that higher BAS activity is associated with a stronger reward to process a better implementation of goal-directed tasks and the diminished processing of secondary cues.

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.

Association of harm avoidance with dopamine D2/3 receptor availability in striatal subdivisions: a high resolution PET study

We examined the relationship between the personality trait of harm avoidance (HA) and the dopamine D(2/3) receptor availability in striatal subdivisions using high resolution positron emission tomography (PET) with [(11)C]raclopride. Twenty-one healthy subjects completed 3T magnetic resonance imaging and high resolution PET scans with [(11)C]raclopride in order to measure D(2/3) receptor availability in subregions of the striatum. The D(2/3) receptor availability was obtained on the basis of the Logan graphical method. The Temperament and Character Inventory was used to measure the biogenetic temperament of HA. The analysis revealed that the HA score had significant negative correlations with D(2/3) receptor availability in the pre-commissural dorsal caudate and post-commissural putamen, suggesting that HA is associated with D(2/3) receptor availability in the associative and sensorimotor subdivisions of the striatum, which are mainly involved in cognition and locomotion. Further research is required to determine if pathological states have similar dopaminergic mechanisms in specific striatal subdivisions.

Inter-individual differences in neurobiology as vulnerability factors for affective disorders: implications for psychopharmacology

Susceptibility to affective disorders is individually different, and determined both by genetic variance and life events that cause significant differences in the CNS structure and function between individual subjects. Therefore it is plausible that search for the inter-individual differences in endophenotypes that mediate the effects of causal factors, both genetic and environmental, will reveal the substrates for vulnerability, help to clarify pathogenetic mechanisms, and possibly aid in developing strategies to discover better, more personalized treatments. This review first examines comparatively a number of animal models of human affect and affect-related disorders that rely on persistent inter-individual differences, and then highlights some of the neurobiological findings in these models that are compatible with much of research in human behavioural and personality traits. Many behaviours occur in specific combinations in several models, but often remarkable dissociations are observed, providing a variety of constellations of traits. It is concluded that more systematic comparative experimentation on behaviour and neurobiology in different models is warranted to reveal possible "building blocks" of affect-related personality common in animals and humans. Looking into the perspectives in psychopharmacology the focus is placed on probable associations of inter-individual differences with brain structure and function, personality and coping strategies, and psychiatric vulnerability, highlighting some unexpected interactions between vulnerability endophenotypes, adverse life events, and behavioural traits. It is argued that further studies on inter-individual differences in affect and underlying neurobiology should include formal modeling of their epistatic, hierarchical and dynamic nature.

Gender difference in relationship between anxiety-related personality traits and cerebral brain glucose metabolism

Recent functional neuroimaging studies have suggested that specific brain regions might be associated with the formation of anxiety-related personality traits, which are well known to be influenced by gender. Such anxiety-related personality traits are one of the representative predisposing factors for mood and anxiety disorders, whose incidence is also known to be much influenced by gender. However, little is known about the gender differences in brain function related to anxiety-related personality traits. The aim of the present study was to examine gender-related differences in the pattern of the relationships between an anxiety-related personality trait and cerebral brain glucose metabolism. Regional brain glucose metabolism was measured using [(18)F]fluorodeoxyglucose positron emission tomography in 102 healthy subjects (65 males and 37 females). An anxiety-related trait was assessed using the Temperament and Character Inventory dimension Harm Avoidance (HA). HA was negatively correlated with glucose metabolism in the anterior portion of the ventromedial prefrontal cortex (vmPFC) in females but not in males. The anterior vmPFC may be a possible neural target for the prevention or therapy of emotional disorders, especially in females.

Physique Correlates with Reproductive Success in an Archival Sample of Delinquent Youth

This study examines predictions from evolutionary psychology about relationships between physique and reproductive success using longitudinal data on 200 delinquent youth from Sheldon's (1949) somatotype research. Number of children (offspring count) in 1979 was used as the measure of reproductive success. Nonparametric bootstrap correlations and confidence intervals were calculated between offspring count and 11 measures of physique (endomorphy, mesomorphy, ectomorphy, andromorphy, gynomorphy, primary structural integration, secondary structural integration, general strength, hand strength, height, and weight). There were noteworthy correlations with mesomorphy, andromorphy, gynomorphy, primary structural integration, secondary structural integration, general strength, and hand strength, all in the directions predicted by evolutionary psychology. While no prediction was made for endomorphy, ectomorphy, or weight; height was expected to be correlated with offspring count, but this study did not find support for this relationship.

Specific personality traits and dopamine, serotonin genes in anxiety-depressive alcoholism among Han Chinese in Taiwan

BACKGROUND

Cloninger [Cloninger CR. 1987. Neurogenetic adaptive mechanisms in alcoholism. Science 236: 410-416.] had proposed a psychobiological model suggesting that three main personality dimensions distinguish the alcoholism into two subtypes (type I and type II). However, the classification was equivocal for clinical diagnosis. Recently, anxiety-depressive alcohol dependence (ANX/DEP ALC) has been posited as a genetically specific subtype of alcoholism. Its clinical characteristics were similar to individuals with type I alcoholism [Cloninger, C.R. 1987. Neurogenetic adaptive mechanisms in alcoholism. Science 236: 410-6.] such as having a high comorbidity with mood disorder, late-onset and more anxious/depressed traits. We attempted to investigate whether the dopamine D2 receptor (DRD2) and the serotonin transporter promoter region (5-HTTLPR) genes were involved in Novelty Seeking (NS) and Harm Avoidance (HA) of ANX/DEP ALC.

METHODS

We recruited 46 pure alcohol dependents (Pure ALC) and 87 anxiety-depression alcohol dependents (ANX/DEP ALC). All participants were diagnosed by DSM-IV criteria, genotyped by the PCR method and assessed with Tridimensional Personality Questionnaire (TPQ).

RESULTS

Both NS and HA were high in ANX/DEP ALC (p = 0.021; p = 0.001, respectively). The association between NS and ANX/DEP ALC only existed in subjects with DRD2 TaqI A1(+) allele (A1/A1 or A1/A2 genotypes) (p = 0.004) and in those with S/S genotype of 5-HTTLPR (p = 0.005). With the stratification of DRD2 TaqI A1(+) allele, high NS of ANX/DEP ALC existed only in carriers of 5-HTTLPR S/S genotype (p=0.001). Moreover, ANX/DEP ALC was related to high HA only in samples carrying 5-HTTLPR S/L or L/L genotype (p = 0.02).

CONCLUSIONS

These findings provided the empirical genetic characterization of the specific personality traits in ANX/DEP ALC among Han Chinese population in Taiwan.

Applications of Clinical Dopamine Imaging

Recent technologic advances make it increasingly possible to image neurotransmitter systems in living human brain, The dopamine system has been most intensively studied owing to its involvement in several brain disorders such as Parkinson's disease and Huntington's disease, as well as psychiatric disorders such as schizophrenia, depression, and compulsive behavioral disorders of multiple types. A variety of aspects of dopamine receptor density, function, and dopaminergic terminal status can now be assessed using the minimally invasive neuroimaging techniques of positron emission tomography and single-photon emission computed tomography. Although these techniques are currently used most often in the context of research, clinical applications are rapidly emerging.

The role of extrastriatal dopamine D2 receptors in schizophrenia

Despite numerous studies on extrastriatal regions involved in schizophrenia, studies on the functional implications of dopamine (DA) D2 receptors in the extrastriatal regions, including the cortex and thalamus, are limited. We review postmortem and in vivo human imaging studies as well as animal studies, focusing on the function of extrastriatal DA D2 receptors and their role in the pathophysiology of schizophrenia. Based on recent findings, cortical DA D2 receptors may interact with the gamma-aminobutyric acid system to modulate DA transmission, and thalamic DA D2 receptors are likely to participate in sensory gating function into the prefrontal cortex. We have found decreased DA D2 receptors in the anterior cingulate cortex and thalamic subregions of patients with schizophrenia. These observations may suggest that alterations of extrastriatal DA D2 receptors are involved in dysregulation of DA transmission and sensory signals from the thalamus to the cortex. Excessive excitatory signals from the thalamus might flow into the cortical neurotransmission system, aggravating dysregulation of DA transmission in both the striatal and extrastriatal regions in schizophrenia. These notions suggest the need for future investigations of extrastriatal DA D2 receptor function to gain important clues regarding the pathogenesis and of possible treatments for schizophrenia.

Temperament in childhood predicts body mass in adulthood: the Cardiovascular Risk in Young Finns Study

This study examined associations of temperament at ages 6 to 12 with body-mass index (BMI) and waist circumference (WC) at ages 24 to 30 years. The participants were 619 men and women derived from the population-based Cardiovascular Risk in Young Finns Study. Temperament was operationalized as (negative) emotionality, sociability, and activity. High emotionality predicted increased BMI, independently of WC, and independently of childhood and adulthood risk factors for adult obesity. None of the temperament dimensions had any associations with WC after controlling for BMI. The findings suggest that temperamental difficulty in childhood may be a useful risk indicator for general body mass in adulthood, and the mechanisms relating temperament with body mass should be further explored.

Changes in EEG and autonomic nervous activity during meditation and their association with personality traits

Meditation is the attainment of a restful yet fully alert physical and mental state practiced by many as a self-regulatory approach to emotion management, but the psychophysiological properties and personality traits that characterize this meditative state have not been adequately studied. We quantitatively analyzed changes in psychophysiological parameters during Zen meditation in 20 normal adults, and evaluated the results in association with personality traits assessed by Cloninger's Temperament and Character Inventory (TCI). During meditation, increases were observed in fast theta power and slow alpha power on EEG predominantly in the frontal area, whereas an increase in the normalized unit of high-frequency (nuHF) power (as a parasympathetic index) and decreases in the normalized unit of low-frequency (nuLF) power and LF/HF (as sympathetic indices) were observed through analyses of heart rate variability. We analyzed the possible correlations among these changes in terms of the percent change during meditation using the control condition as the baseline. The percent change in slow alpha EEG power in the frontal area, reflecting enhanced internalized attention, was negatively correlated with that in nuLF as well as in LF/HF and was positively correlated with the novelty seeking score (which has been suggested to be associated with dopaminergic activity). The percent change in fast theta power in the frontal area, reflecting enhanced mindfulness, was positively correlated with that in nuHF and also with the harm avoidance score (which has been suggested to be associated with serotonergic activity). These results suggest that internalized attention and mindfulness as two major core factors of behaviors of mind during meditation are characterized by different combinations of psychophysiological properties and personality traits.

Effect of reduction in endogenous dopamine on extrastriatal binding of [11C]FLB 457 in rat brain—An ex vivo study

Carbon-11 labeled FLB 457 has been used successfully as a selective, high affinity PET ligand for the quantification of extrastriatal D2-like receptors in man. This study was carried out in rats to investigate regional values for maximal binding and ED50 (a measure of apparent K(d)) for the radioligand in vivo in control animals and in a group pretreated with the neuronal impulse flow inhibitor, gamma-butyrolactone. The aims were to obtain further information regarding the specific activity needed to ensure tracer kinetics and to investigate baseline occupancy by dopamine (DA), each relevant to optimal clinical use of the radioligand. Regional B(max) values were consistent with the distribution of D2-like receptors in rat brain. Of interest, 60% of the binding in cerebellum, often used as a low-binding "reference region" for PET quantification, was saturable, with B(max) only 2- to 3-fold less than that in neocortex, hippocampus, and thalamus. ED50 values were in the range 2-3 nmol/kg, confirming minimal receptor occupancy by the tracer in human PET, using high but achievable specific activities. In the majority of extrastriatal tissues, reduction in synaptic DA did not significantly decrease the apparent K(d), except in cortical regions, where the extent of the effect suggested a low ( approximately 10%), but measurable baseline receptor occupancy by DA.

Novelty seeking and harm avoidance in Parkinson's disease: effects of asymmetric dopamine deficiency

OBJECTIVES

Although changes in novelty seeking and harm avoidance have been reported among patients with Parkinson's disease (PD), the findings regarding the neurochemical correlates of such changes are inconsistent. This study was designed to examine the hypothesis that different patterns of motor and neurochemical asymmetry in PD may have contributed to the conflicting results.

METHODS

Forty PD patients (divided into two groups according to initial asymmetry in dopamine deficit: left hemisphere, n = 22; right hemisphere, n = 18) and 17 age matched healthy controls completed the Tridimensional Personality Questionnaire (Cloninger, 1987).

RESULTS

Only patients with greater dopamine loss in the left hemisphere showed reduced novelty seeking, whereas only patients with reduced dopamine in the right hemisphere reported higher harm avoidance than matched healthy controls. Novelty seeking was not associated with disease duration, current motor symptoms, or medication, whereas harm avoidance was significantly correlated only with the severity of bradykinesia and depression.

CONCLUSIONS

Approach and avoidance reflect different patterns of dopaminergic asymmetry. Whereas reduced novelty seeking reflects deficit in the mesolimbic branch of ascending dopamine transmission in the left hemisphere, increased harm avoidance is associated with greater dopamine loss in the right striatum.

Dopamine dysfunction in borderline personality disorder: a hypothesis

Research on the biological basis of borderline personality disorder (BPD) has focused primarily on the serotonin model of impulsive aggression. However, there is evidence that dopamine (DA) dysfunction may also be associated with BPD. Pertinent research and review articles, identified by Medline searches of relevant topics, books, references from bibliographies, and conference proceedings from 1975 to 2003, were reviewed. Evidence of DA dysfunction in BPD derives from the efficacy of traditional and atypical antipsychotic agents in BPD, and from provocative challenges with amphetamine and methylphenidate of subjects with the disorder. In addition, human and animal studies indicate that DA activity plays an important role in emotion information processing, impulse control, and cognition. The results of this review suggest that DA dysfunction is associated with three dimensions of BPD, that is, emotional dysregulation, impulsivity, and cognitive-perceptual impairment. The main limitation of this hypothesis is that the evidence reviewed is circumstantial. There is no study that directly demonstrates DA dysfunction in BPD. In addition, the therapeutic effects of antipsychotic agents observed in BPD may be mediated by non-DA mechanisms of action. If the stated hypothesis is correct, DA dysfunction in BPD may result from genetic, developmental, or environmental factors directly affecting specific DA pathways. Alternatively, DA dysfunction in BPD may be a compensatory response to alterations in the primary neural systems that control emotion, impulse control, and cognition, and that are mediated by the brain's main neurotransmitters, glutamate, and GABA, or in one or more other neuromodulatory pathways such as serotonin, acetylcholine, and norepinephrine.

D2 dopamine receptor gene polymorphism: paroxetine and social functioning in posttraumatic stress disorder

This study examined whether allelic status of the D2 dopamine receptor (DRD2) gene was associated with response to a selective serotonin reuptake inhibitor, paroxetine, in the treatment of posttraumatic stress disorder (PTSD). Sixty-three Caucasian war veterans with combat-related PTSD were treated with paroxetine for 8 weeks. Patients were assessed at baseline and at follow-up using the General Health Questionnaire-28 (GHQ). TaqI A DRD2 alleles were determined by PCR. Before paroxetine treatment, patients with the DRD2 A1+ allele (A1A2 genotype) compared to those with the A1- allele (A2A2 genotype) had higher total GHQ psychopathological scores (P=0.040) and higher GHQ subscale scores for anxiety/insomnia (0.046), social dysfunction (P=0.033) and depression (P=0.011). In an intention-to-treat analysis, paroxetine was associated with significant improvement in total GHQ scores (P=0.014) and in the factor scores of social dysfunction (P=0.033), anxiety (P=0.009) and depression (P=0.026). Furthermore, there was a significant allele by time interaction on the social dysfunction scale, with A1+ allelic patients showing significant improvement in social functioning compared to A1- allelic patients (P=0.031), an effect independent of changes in depression or anxiety. This suggests changes in social functioning induced by paroxetine may be, in part, mediated via D2 dopamine receptors. The DRD2 A1 allele may prove to be a useful marker to assist clinicians in predicting which patients with PTSD are likely to obtain improvements in social functioning with paroxetine treatment.

An Alternative Way to Individualized Medicine: Psychological and Physical Traits of Sasang Typology

BACKGROUND

Disease susceptibility and drug response of individuals are presumed to be different depending on their personality traits. The Sasang typology, a traditional Korean medical typology, explains the individual differences of vulnerability to pathology and proposes guidelines for the safe and effective use of medical herbs depending on individual traits.

OBJECTIVE

The purpose of the present study was to evaluate psychologic and physical characteristics of Sasang types from the perspective of personality theory.

DESIGN

After determining the Sasang type of 79 college students based on the Questionnaire for the Sasang Constitution Classification, the psychologic and physical traits of each type were analyzed by the Meyers-Briggs Type Indicator (MBTI) and Bioelectrical Impedance Analysis, respectively.

RESULTS

Each of the Sasang types showed significantly different profiles based on the MBTI scores (generalized estimation equation, coefficient = 11.88, z = 2.13, p = 0.033) and could be distinctively classified based on their MBTI scores (discriminant analysis Wilks' lambda = 0.611, df = 8, chi(2) = 36.7, p < 0.001). Subjects with the So-Eum type (Introversion and Judging) and the So-Yang type (Extroversion and Perceiving) showed contrasting psychologic features. However, they had similar anthropometric characteristics. Subjects with Tae-Eum type had relatively higher body fat mass.

CONCLUSION

Current results demonstrated distinctive personality traits associated with Sasang types using reproducible psychometric and anthropometric instruments. With further study, the Sasang typology could serve as a scientific tool for individualized and integrative medicine.

Personality traits and striatal 6-[18F]fluoro-L-dopa uptake in healthy elderly subjects

Positron emission tomography (PET) studies have been carried out to examine dopaminergic correlates of human personality traits. In patients with Parkinson's disease, right caudate 6-[(18)F]fluoro-L-dopa ((18)F-dopa) uptake has recently been reported to correlate with a depression/anxiety related-personality trait of harm avoidance. The present study aimed to further study personality and striatal dopaminergic function, now with (18)F-dopa in healthy individuals, and to determine specifically whether the link between harm avoidance and (18)F-dopa uptake is a general phenomenon, seen also in healthy subjects. Twenty-five Caucasian neurologically healthy elderly subjects (mean age=60 years; 13 men, 12 women) were scanned with 3D (18)F-dopa PET, coregistered with magnetic resonance imaging, and each subject filled out the Temperament and Character Inventory (TCI) and the Karolinska Scales of Personality (KSP). The TCI harm avoidance did not correlate with right caudate (18)F-dopa uptake (r=-0.08, P=0.71, uncorrected, effects of age and sex partialled out), or with the (18)F-dopa uptake in any other striatal region (r=-0.07-0.16, P>0.47). Correlations with other personality scales, including the TCI novelty-seeking and the KSP detachment, were also non-significant. The results indicate that the previous positive findings concerning harm avoidance and (18)F-dopa uptake in Parkinson's disease are disease-related, and that they can not be generalized to healthy individuals.

Personality traits and brain dopaminergic function in Parkinson's disease

A distinctive personality type, characterized by introversion, inflexibility, and low novelty seeking, has been suggested to be associated with Parkinson's disease. To test the hypothesis that Parkinson's disease is associated with a specific dopamine-related personality type, the personality structures of 61 unmedicated Parkinson's disease patients and 45 healthy controls were examined. Additionally, in 47 Parkinson's disease patients, the dopaminergic function in the brain was directly measured with 6-[(18)F]fluoro-l-dopa ((18)F-dopa) positron emission tomography (PET) with MRI coregistration. The novelty-seeking personality score, supposedly associated with the parkinsonian personality, was slightly lower in the Parkinson's disease group compared with controls, but it did not have a significant relationship with (18)F-dopa uptake in any of the brain regions studied (r = -0.12 to 0.11, P > 0.15). The harm-avoidance personality score, associated with anxiety and depression, was clearly increased in patients with Parkinson's disease and it had a paradoxical, highly significant positive correlation with the (18)F-dopa uptake in the right caudate nucleus (r = 0.53, P = 0.04, Bonferroni corrected for 220 comparisons). Although the results of this study are not in disagreement with the concept of low-novelty-seeking personality type in Parkinson's disease, the personality type does not seem to be dopamine dependent. The correlation between the personality trait of harm avoidance and (18)F-dopa may reflect a specific feedback circuitry of neurotransmitters that is associated with negative emotionality in Parkinson's disease.

Determinants of food choice: relationships with obesity and weight control

The decision to eat, and to eat particular foods, varies for different individuals and situations. Individual differences in food likes and desires develop throughout life because of differing food experiences and attitudes. There are many internal and external cues, not just stimulation from foods or hunger, which can trigger the immediate desire to eat or orient eating toward certain foods. Food desires and intake are an outcome of interactions between these cues and more stable individual physiological and psychological characteristics. Overweight and obese individuals show a tendency toward greater liking and selection of energy-dense foods, which may contribute to development and maintenance of these conditions. However, although liking (pleasure from eating) is an important part of food choice, it may make only a modest contribution to overall variation in food choice and eating behaviors. Indeed, difficulties of weight control may reflect problems with cues and motivations to eat, rather than with heightened pleasure derived from eating. Paradoxically, individuals highly concerned with food intake and weight control may be particularly susceptible to thoughts, emotions, and situational cues that can prompt overeating and undermine their attempts to restrain eating. Repeat dieting, high day-to-day fluctuations in intakes, and attempts to enforce highly rigid control over eating all seem to be counterproductive to weight control efforts and may disrupt more appropriate food choice behaviors. Longer-term weight maintenance solutions and programs that offer a degree of structuring of the personal food environment, while retaining flexibility in choices, therefore, may be particularly beneficial in weight management.