D4 dopamine receptor gene exon III polymorphism and obesity risk

Underlying Susceptibility to Eating Disorders and Drug Abuse: Genetic and Pharmacological Aspects of Dopamine D4 Receptors

The dopamine D4 receptor (DRD4) has a predominant expression in the prefrontal cortex (PFC), brain area strictly involved in the modulation of reward processes related to both food and drug consumption. Additionally, the human DRD4 gene is characterized by a variable number of tandem repeats (VNTR) in the exon 3 and, among the polymorphic variants, the 7-repeat (7R) allele appears as a contributing factor in the neurobiological mechanisms underlying drug abuse, aberrant eating behaviors and related comorbidities. The 7R variant encodes for a receptor with a blunted intracellular response to dopamine, and carriers of this polymorphism might be more tempted to enhance dopamine levels in the brain, through the overconsumption of drugs of abuse or palatable food, considering their reinforcing properties. Moreover, the presence of this polymorphism seems to increase the susceptibility of individuals to engage maladaptive eating patterns in response to negative environmental stimuli. This review is focused on the role of DRD4 and DRD4 genetic polymorphism in these neuropsychiatric disorders in both clinical and preclinical studies. However, further research is needed to better clarify the complex DRD4 role, by using validated preclinical models and novel compounds more selective for DRD4.

Examining the Impact of Maternal Individual Features on Children's Behavioral Problems in Adoptive Families: The Role of Maternal Temperament and Neurobiological Markers

The first year after adoption constitutes a sensitive period for both strengthening the new emotional bond in the family and checking its appropriate development by adoption services. A key variable for children’s catch-up are adoptive parents’ socioemotional and individual features. The aim of this study is to investigate links between adoptive mothers’ individual features and behavioral problems in their children in the first year after adoption placement, by testing the moderating role of both age at adoption and maternal genetic polymorphisms. Seventy-eight adoptive mothers completed temperament and genetic measures. Mothers showed a specific pattern of interaction between basic temperament traits and genetic markers in their assessment of children’s behavioral problems; dopamine D4 receptor gene and children’s age at adoption are two moderators in the association in which mothers’ temperament was affecting the evaluation of their children’s behavioral problems. Findings highlight a still undervalued area of parenting resources in the process of post-institutionalized children’s catch-up after adoption placement, by showing how individual features count in the commonly measured variable of children’s behavioral and emotional problems. This could help in orienting identification and choice of key variables for family assessment after adoption placement, thus contributing in fostering children’s healthy development.

Gene and environment interaction: Is the differential susceptibility hypothesis relevant for obesity?

The differential susceptibility model states that a given genetic variant is associated with an increased risk of pathology in negative environments but greater than average resilience in enriched ones. While this theory was first implemented in psychiatric-genetic research, it may also help us to unravel the complex ways that genes and environments interact to influence feeding behavior and obesity. We reviewed evidence on gene vs. environment interactions that influence obesity development, aiming to support the applicability of the differential susceptibility model for this condition, and propose that various environmental "layers" relevant for human development should be considered when bearing the differential susceptibility model in mind. Mother-child relationship, socioeconomic status and individual's response are important modifiers of BMI and food intake when interacting with gene variants, "for better and for worse". While only a few studies to date have investigated obesity outcomes using this approach, we propose that the differential susceptibility hypothesis is in fact highly applicable to the study of genetic and environmental influences on feeding behavior and obesity risk.

Is there a bi-directional relationship between depression and obesity among adult men and women? Systematic review and bias-adjusted meta analysis

The rapidly increasing prevalence of both obesity and depression represent two major public health concerns worldwide. But the evidence regarding the direction and strength of the association between these two disorders, for both adult men and women, are remain inconclusive. We systematically reviewed publications from five different databases: Pubmed, Embase, BIOSIS, CINAHL and PsychINFO. A total of 21 articles were included for the systematic review and 19 of them for the meta-analysis using a bias-adjusted (quality effect) model. This resulted in the inclusion of approximately 226,063 (33.7% men) participants. Those who were depressed had a 37% (RR: 1.37, 95% CI: 1.17, 1.48) increased risk of being obese, and who were obese had an 18% increased risk of being depressed (RR: 1.18, 95% CI: 1.04, 1.35). Those who were depressed had a 2% (RD: 0.02, 95% CI: 0.01, 0.03) excess risk of obesity, however, the reciprocal associations were not significant. The association between overweight and depression was not found significant in either direction. Both men and women were at risk of obesity and depression bi-directionally. In sensitivity analyses bi-directional associations were more pronounced among young and middle aged adults and in studies with longer follow-up. The findings of this study suggest that the strength of the association is greater for the direction leading from depression to obesity and this link was more pronounced for young and middle aged women.

Attention deficit hyperactivity disorder symptomatology and pediatric obesity: Psychopathology or sleep deprivation?

The relationship between attention deficit hyperactivity disorder (ADHD) and obesity in children has received considerable attention in recent years. However, the literature currently overlooks the potential causal and maintaining role that sleep problems may play in this relationship. Using a biopsychosocial framework, this article highlights how sleep problems impact the biological, psychological, and social aspects of both ADHD symptomatology and obesity. An in-depth examination of this model illustrates the imperative need for future research and clinical practice to recognize and explore the role sleep has in the link between obesity and ADHD symptomatology.

Blocking alpha2A adrenoceptors, but not dopamine receptors, augments bupropion-induced hypophagia in rats

OBJECTIVE

Anti-obesity drugs have adverse effects which limit their use, creating a need for novel anti-obesity compounds. We studied effects of dopamine (DA) and norepinephrine (NE) reuptake inhibitor bupropion (BUP), alone and after blocking α1- or α2-adrenoceptors (AR), D1/5, D2/3, or D4 receptors, to determine which receptors act downstream of BUP.

DESIGN AND METHODS

Effects on caloric intake, meal patterning and locomotion were assessed, using an automated weighing system and telemetry in male rats with 18-h access to Western Human style diet.

RESULTS

BUP (30 mg/kg) induced hypophagia by reducing meal size and postponing meal initiation. WB4101 (α1-AR; 2 mg/kg) and imiloxan (α2B-AR; 5 mg/kg) attenuated BUP's effect on meal size, while WB4101 and BRL 44408 (α2A/D-AR; 2 mg/kg) counteracted effect on meal initiation. Atipamezole (α2-AR; 1 mg/kg) and imiloxan further postponed initiation of meals. SKF 83566 (D1/5; 0.3 mg/kg), raclopride (D2/3; 0.5 mg/kg) and to a lesser extent FAUC 213 (D4; 0.5 mg/kg), attenuated BUP-induced hypophagia. BUP stimulated locomotion, which was blocked by all antagonists, except FAUC 213 or BRL 44408.

CONCLUSIONS

Alpha1-, α2A/D- and α2B-ARs, and DA receptors underlie BUP's effects on size and initiation of meals, while blocking pre-synaptic α2-ARs enhanced BUP-induced hypophagia. An inverse agonist of (pre-synaptic) α2A-ARs could enhance BUP-induced anorexia and treat eating disorders and obesity.

Prevalence of obesity and overweight among Chinese children with attention deficit hyperactivity disorder: a survey in Zhejiang Province, China

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is often comorbid with psychiatric and developmental disorders. This study aimed to investigate the prevalence of obesity and overweight among Chinese children with ADHD, and to explore which subtypes of the disorder may specifically be associated with obesity/overweight.

METHODS

Children meeting the DSM-IV criteria for ADHD were enrolled in the study. Weight, weight z-score, height, height z-score, BMI, and BMI z-score were used to evaluate growth status. Obesity and overweight were determined using the National Growth Reference for Chinese Children and Adolescents. Relations between the prevalence of obesity/overweight and different ADHD subtypes and pubertal development were analyzed.

RESULTS

A total of 158 children with ADHD (mean age: 9.2 years) were recruited for the study. The prevalences of obesity, overweight, and combined obesity/overweight were 12.0%, 17.1%, and 29.1%, respectively, which were significantly higher than in the general Chinese population (2.1%, 4.5%, and 6.6%, respectively). Multivariable analysis showed that the children with the combined subtype of ADHD and the onset of puberty were at a higher risk of becoming obese or overweight.

CONCLUSIONS

The prevalence of obesity in Chinese children with ADHD is higher than that of the general population. Children with the ADHD combined subtype who were at the onset of puberty were more likely to be overweight or obese.

Reduction of bulimia nervosa symptoms after psychostimulant initiation in patients with comorbid ADHD: five case reports

Studies reveal a higher occurrence of bulimia nervosa (BN) in patients with attention deficit/hyperactivity disorder (ADHD) compared to controls. Due to this high degree of comorbidity, some clinicians have used psychostimulants in this population. The goal of this article is to describe five patients with comorbid BN and ADHD and their responses to a course of psychostimulants. After medication initiation, all five patients experienced a decrease in binge/purging and an improvement in ADHD symptoms. Overall, the medications were well tolerated. Possible mechanisms underlying the relationship between ADHD and BN, and words of caution are discussed. The need for clinical trials to further evaluate the efficacy of psychostimulants in this population is warranted.

Factors associated with attention deficit/hyperactivity disorder among US children: results from a national survey

Background

The purpose of this study was to investigate the association between Attention Deficit/Hyperactivity Disorder (ADHD) and various factors using a representative sample of US children in a comprehensive manner. This includes variables that have not been previously studied such as watching TV/playing video games, computer usage, family member’s smoking, and participation in sports.

Methods

This was a cross-sectional study of 68,634 children, 5–17 years old, from the National Survey of Children’s Health (NSCH, 2007–2008). We performed bivariate and multivariate logistic regression analyses with ADHD classification as the response variable and the following explanatory variables: sex, race, depression, anxiety, body mass index, healthcare coverage, family structure, socio-economic status, family members’ smoking status, education, computer usage, watching television (TV)/playing video games, participation in sports, and participation in clubs/organizations.

Results

Approximately 10% of the sample was classified as having ADHD. We found depression, anxiety, healthcare coverage, and male sex of child to have increased odds of being diagnosed with ADHD. One of the salient features of this study was observing a significant association between ADHD and variables such as TV usage, participation in sports, two-parent family structure, and family members’ smoking status. Obesity was not found to be significantly associated with ADHD, contrary to some previous studies.

Conclusions

The current study uncovered several factors associated with ADHD at the national level, including some that have not been studied earlier in such a setting. However, we caution that due to the cross-sectional and observational nature of the data, a cause and effect relationship between ADHD and the associated factors can not be deduced from this study. Future research on ADHD should take into consideration these factors, preferably through a longitudinal study design.

Obesity and ADHD: clinical and neurobiological implications

Although quite overlooked, increasing evidence points to a significant association between attention-deficit/hyperactivity disorder (ADHD) and obesity. Here, we present an updated systematic review and a critical discussion of studies on the relationship between ADHD and obesity, with a particular emphasis on the possible behavioral, neurobiological, and genetics underlying mechanisms. Available empirically based studies indicate that the prevalence of ADHD in clinical samples of patients seeking treatment for their obesity is higher than that in the general population. Moreover, although still limited, current evidence shows that individuals with ADHD have higher-than-average body mass index z-scores and/or significantly higher obesity rates compared with subjects without ADHD. Three mechanisms underlying the association between ADHD and obesity have been proposed: (1) obesity and/or factors associated with it (such as sleep-disordered breathing and deficits in arousal/alertness) manifest as ADHD-like symptoms; (2) ADHD and obesity share common genetics and neurobiological dysfunctions, involving the dopaminergic and, possibly, other systems (e.g., brain-derived neurotropic factor, melanocortin-4-receptor); and (3) impulsivity and inattention of ADHD contribute to weight gain via dysregulated eating patterns. With regards to the possible clinical implications, we suggest that it is noteworthy to screen for ADHD in patients with obesity and to look for abnormal eating behaviors as possible contributing factors of obesity in patients with ADHD. If further studies confirm a causal relationship between ADHD and obesity, appropriate treatment of ADHD may improve eating patterns and, as a consequence, weight status of individuals with both obesity and ADHD.

Comorbidity between ADHD and obesity: exploring shared mechanisms and clinical implications

Recent studies suggest an association between attention-deficit/hyperactivity disorder (ADHD) and obesity. In this article, we systematically review and critically discuss evidence on the prevalence of ADHD in obese patients as well as the weight status of individuals with ADHD. Relevant articles were searched in PubMed, PsychInfo, and ISI Web of Science (January 1980 to June 2010). We found that current evidence indicates a high prevalence of ADHD in clinical samples of patients seeking treatment for their obesity. Moreover, available studies show that individuals with ADHD have higher-than-average body mass index z scores and/or a significantly higher prevalence of obesity compared with subjects without ADHD. Three mechanisms underlying the association between ADHD and obesity have been proposed: 1) it is possible that obesity and/or factors associated with it (such as sleep-disordered breathing) manifest as ADHD-like symptoms; 2) ADHD and obesity share common biological dysfunctions; and 3) ADHD contributes to obesity. With regards to the possible clinical implications, our findings suggest that it is noteworthy to screen for ADHD in patients with obesity and to look for abnormal eating behaviors as possible contributing factors of obesity in patients with ADHD. Based on preliminary findings, appropriate treatment of ADHD may improve the weight status of individuals with both obesity and ADHD.

Depression and obesity: do shared genes explain the relationship?

BACKGROUND

Studies have found a modest association between depression and obesity, especially in women. Given the substantial genetic contribution to both depression and obesity, we sought to determine whether shared genetic influences are responsible for the association between these two conditions.

METHODS

Data were obtained from 712 monozygotic and 281 dizygotic female twin pairs who are members of the community-based University of Washington Twin Registry. The presence of depression was determined by self-report of doctor-diagnosed depression. Obesity was defined as body mass index of > or =30 kg/m(2), based on self-reported height and weight. Generalized estimating regression models were used to assess the age-adjusted association between depression and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental influences.

RESULTS

We found a modest phenotypic association between depression and obesity (odds ratio=1.6, 95% confidence interval=1.2-2.1). Additive genetic effects contributed substantially to depression (57%) and obesity (81%). The best-fitting bivariate model indicated that 12% of the genetic component of depression is shared with obesity.

CONCLUSIONS

The association between depression and obesity in women may be in part due to shared genetic risk for both conditions. Future studies should examine the genetic, environmental, social, and cultural mechanisms underlying the relationship between this association.

Dopamine D4 receptor (D4R) deletion in mice does not affect operant responding for food or cocaine

In this study we examined the genetic contribution of the D4R in food and cocaine self-administration using D4R mice. Mice were examined for operant responding to food pellets or intravenous cocaine. Compared to wild-type mice (D4R(+/+)), both heterozygous (D4R(+/-)) and knockout (D4R(-/-)) mice showed no difference in responding for food or cocaine. Our findings suggest that the D4R is not directly involved in mediating operant response behaviors for food or cocaine.

Minor genetic variants of the dopamine D4 receptor (DRD4) polymorphism are associated with novelty seeking in healthy Japanese subjects

Although an association between the dopamine receptor D4 (DRD4) gene and personality traits had been previously investigated, results from previous studies were not conclusive. This may be due to the method of grouping used, which categorized the gene population into two groups based on the length of the variable number of tandem repeats (VNTR) in exon 3. In the present study, we categorized 616 healthy Japanese subjects into more than two groups by further subdividing the DRD4 48-bp VNTR polymorphism, and compared Temperament and Character Inventory (TCI) scores among the groups. A significant difference was found between the DRD4 48-bp VNTR polymorphism and novelty seeking (p=0.016). The novelty-seeking scores in the subjects carrying the 5/5 genotype were significantly higher than in those carrying the 2/2 genotype (p=0.002) or the 4/4 genotype (p=0.005). However, when the conventional method of grouping was used (i.e., short alleles vs. long alleles), there were no significant associations between the DRD4 VNTR polymorphism and any TCI scores. Our results suggest that minor 5-repeat allele is associated with high novelty-seeking scores in healthy Japanese subjects.

Role of shared genetic and environmental factors in symptoms of depression and body composition

BACKGROUND

Both obesity and lean mass have been correlated with symptoms of depression.

OBJECTIVE

To investigate the contribution of genetic and environmental factors in the co-occurrence of obesity and lean mass with symptoms of depression.

METHODS

Individuals were 2383 participants of the Erasmus Rucphen Family study. Symptoms of depression were assessed using the Center for Epidemiologic Studies Depression Scale and the Hospital Anxiety and Depression Scale. Anthropometric and dual-energy X-ray absorptiometry total body scans were obtained for the assessment of body composition. The role of shared genetic and shared environmental factors was quantified by estimating genetic and environmental correlations between symptoms of depression and measures of body composition.

RESULTS

Phenotypic correlations between body composition and symptoms of depression ranged from -0.08 to 0.08. Heritability estimates for body composition ranged from 0.40 to 0.46 (P<0.001) in women and from 0.35 to 0.51 (P<0.001) in men, and heritability estimates for depression scores were higher in women (0.34 and 0.37) than in men (0.13 and 0.21). No consistent genetic correlations between measures of body composition and symptoms of depression were found. We did find a significant consistent environmental correlation between depression scores and lean mass index (environmental correlation=-0.23 for Center for Epidemiologic Studies Depression Scale and -0.31 for Hospital Anxiety and Depression Scale).

CONCLUSION

In our study, there is no evidence that the co-occurrence of symptoms of depression and body composition result from a common genetic pathway.

Obesity is Associated with Genetic Variants That Alter Dopamine Availability

Human and animal studies have implicated dopamine in appetite regulation, and family studies have shown that BMI has a strong genetic component. Dopamine availability is controlled largely by three enzymes: COMT, MAOA and MAOB, and by the dopamine transporter SLC6A3, and each gene has a well-characterized functional variant. Here we look at these four functional polymorphisms together, to investigate how heritable variation in dopamine levels influences the risk of obesity in a cohort of 1150, including 240 defined as obese (BMI > or = 30). The COMT and SLC6A3 polymorphisms showed no association with either weight, BMI or obesity risk. We found, however, that both MAOA and MAOB show an excess of the low-activity genotypes in obese individuals (MAOA:chi2= 15.45, p = 0.004; MAOB:chi2= 8.05, p = 0.018). Additionally, the MAOA genotype was significantly associated with both weight (p = 0.0005) and BMI (p = 0.001). When considered together, the 'at risk genotype'--low activity genotypes at both the MAOA and MAOB loci--shows a relative risk for obesity of 5.01. These results have not been replicated and, given the experience of complex trait genetics, warrant caution in interpretation. In implicating both the MAOA and MOAB variants, however, this study provides the first indication that dopamine availability (as opposed to other effects of MAOA) is involved in human obesity. It is therefore a priority to assess the associations in replication datasets.

Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data

BACKGROUND

Two variants in the dopamine D4 receptor (DRD4) gene have been reported to be associated with human approach-related traits such as novelty seeking and extraversion. However, the strength of evidence for this association remains uncertain.

METHODS

We conducted a meta-analysis of published studies of the association between the DRD4 gene variable number of tandem repeats (VNTR) and C-521T polymorphisms and human approach-related personality traits, including novelty seeking, extraversion, and impulsivity, restricted to adult samples recruited from nonpsychiatric populations, and extended on this literature by attempting to confirm any evidence of association in a replication sample (n = 309) selected for extreme scores on the extraversion subscale of the Eysenck Personality Questionnaire from a large (n = 40,090) population-based sample.

RESULTS

Our initial meta-analysis supported the association of the DRD4 C-521T polymorphism, but not the VNTR polymorphism, with approach-related traits. This conclusion was qualified by evidence of significant publication bias and the failure to detect association in a replication sample comprising individuals at the extremes of the trait distribution. The association of the C-521T polymorphism observed in our initial meta-analysis was robust to the inclusion of these new data, but our revised meta-analysis indicated that the association was present for measures of novelty seeking and impulsivity but not for measures of extraversion.

CONCLUSIONS

The DRD4 gene may be associated with measures of novelty seeking and impulsivity but not extraversion. The association of the C-521T variant with these measures, if genuine, may account for up to 3% of phenotypic variance.

Does dopaminergic reward system contribute to explaining comorbidity obesity and ADHD?

Some recent studies have reported a strong link between obesity and attention-deficit/hyperactivity disorder (ADHD). However, to date, the factors underlying this newly described comorbidity are still unclear and unexplored. In the present article, we proposed that the dopamine system and implicate dopamine genes contribute to explaining the association between ADHD and obesity. The background for this hypothesis comes from studies on the association between ADHD and dopamine, as well as from investigations on dopamine in obese individuals. There is strong evidence that indicate catecholamines dopamine is very important in the pathophysiology of ADHD, as well as in the mechanism of therapeutic action of stimulant drugs. Furthermore, increasing evidence indicated that dopaminergic reward system is significantly associated with obesity. With regard to the therapeutic implications, recent studies indicate that methylphenidate (MPH) - a drug widely used for ADHD reduced overall energy intake with a selective reduction in dietary fat. Findings are consistent with a reward deficiency model of obesity whereby low brain dopamine predicts overeating and obesity, and administering agents that increase dopamine results in reduced feeding behavior. Given the above background, we hypothesize that the increased prevalence of ADHD in obese individual could be explained by the imbalance of dopaminergic reward system.

Anorexia nervosa, perfectionism, and dopamine D4 receptor (DRD4)

The dopamine D4 receptor (DRD4), a well-characterized, polymorphic gene, is an attractive candidate for contributing risk to disordered eating and anorexia nervosa (AN). We tested association using UNPHASED for 5 DRD4 polymorphic loci, 3 promoter region SNPs (C-521T, C-616G, A-809G), the 120 bp promoter region tandem duplication and the exon III repeat, in 202 AN trios and 418 control families. Since perfectionism characterizes AN, we tested these five loci for association with the Child and Adolescent Perfectionism Scale (CAPS) in the AN and control groups. Single locus analysis showed significant association between the 'C' C-521T allele and AN. Haplotype analysis also showed significant association, particularly a 4-locus haplotype (exon III&120 bp repeat&C-521T&A-809G). Association was also observed between DRD4 and CAPS scores both for AN and control subjects. The insulin-like growth factor 2 (IGF2) and the arginine vasopressin 1a receptor (AVPR1a), previously shown to be associated with disordered eating, were also associated with CAPS scores. Three genes associated with AN were also associated with perfectionism. Personality traits are potential endophenotypes for understanding the etiology of eating disorders and one of the several pathways to eating pathology may be mediated by the impact of DNA sequences on perfectionism.

Gene-environment contributions to young adult sexual partnering

To date, there has been relatively little work on gene-environment contributions to human sexuality, especially molecular analyses examining the potential contributions of specific polymorphisms in conjunction with life experiences. Using Wave III data from 717 heterozygous young adult sibling pairs included in the National Longitudinal Study of Adolescent Health, this article examined the combined contributions of attendance at religious services and three genetic polymorphisms (in the dopamine D4 receptor [DRD4]), dopamine D2 receptor [DRD2]), and the serotonin transporter promoter [5HTT]) to sensation seeking, a personality construct related to sexual behavior, and the number of vaginal sex partners participants had in the year before interview. Data analyses used an Allison mixed model approach to account for population stratification and correlated observations. DRD4 was unrelated to sensation seeking and to the number of sex partners in tests of both main effects and in interaction with religious attendance. Contrary to hypothesis, presence of the A1 DRD2 allele was associated with having had fewer sex partners in the past year. Associations between the 5HTT allele and sex partners varied by religious attendance, but again the patterns of associations were contrary to hypothesized relationships and were small in magnitude. These findings underscore the necessity of using more comprehensive multiple gene-multiple life experience approaches to investigations of complex behaviors such as sexual patterns.

Obesity and ADHD may represent different manifestations of a common environmental oversampling syndrome: a model for revealing mechanistic overlap among cognitive, metabolic, and inflammatory disorders

Obesity and attention-deficit hyperactivity disorder (ADHD) are both increasing in prevalence. Childhood exposure to television has shown linkage to both ADHD and obesity with the former ascribed to dysfunctional cognitive hyperstimulation and the latter to altered patterns of diet and exercise. Empirical evidence has contradicted prior presumptions that the hyperactivity of ADHD would decrease the risk of obesity. Instead, obesity and ADHD demonstrate significant comorbidity. We propose that obesity and ADHD represent different manifestations of the same underlying dysfunction, a phenomenon we term environmental oversampling syndrome. Oversupply of information in the form of nutritional content and sensory content may independently predispose to both obesity and ADHD. Moreover, the pathogenic mechanisms of these conditions may overlap such that nutritional excess contributes to ADHD and cognitive hyperstimulation contributes to obesity. The overlapping effects of medications provide further evidence towards the existence of shared etiologic pathways. Metabolism and cognition may represent parallel systems of intelligence, and oversampling of content may constitute the source of parallel dysfunctions. The emerging association between psychiatric and metabolic disorders suggests a fundamental biologic link between these two systems. In addition, the immune system may represent yet another form of intelligence. The designation of syndrome X subsumes seemingly unrelated metabolic and inflammatory entities. Environmental oversampling syndrome may represent an even more inclusive concept that encompasses various metabolic, inflammatory, and behavioral conditions. Apparently disparate conditions such as insulin resistance, diabetes, hypertension, syndrome X, obesity, ADHD, depression, psychosis, sleep apnea, inflammation, autism, and schizophrenia may operate through common pathways, and treatments used exclusively for one of these conditions may prove beneficial for the others.

Smoking cessation, weight gain, and DRD4 -521 genotype

We investigated change in body mass index following long-term smoking cessation in a representative cohort of treatment-seeking heavy smokers in the United Kingdom, to determine the extent of long-term weight gain in successful quitters versus continuing smokers. We further investigated whether DRD4 genotype moderated any weight gain in either group. Smoking cessation was associated with an increase in BMI, and persisted up to 8 years after smoking cessation. Ex-smokers at 8-year follow-up weighed over 2.5 kg/m(3) more on average than they did at baseline, while participants who were smokers at both baseline and 8-year follow-up did not demonstrate any change in BMI. We did not observe an interaction between smoking status and DRD4 genotype. However, independently of the weight gain among those who stopped smoking during the course of the study, DRD4 genotype was significantly associated with BMI, with possession of the -521 C-allele associated with increased BMI. The magnitude of increase in BMI following smoking cessation, and the persistence of this change at 8-year follow-up, suggests that health benefits associated with smoking cessation may to some extent be negated by the detrimental effects on health of associated weight gain. Smoking cessation programmes should therefore consider incorporating follow-up support to promote weight loss among those who successfully stop smoking.

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.

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.

Characterization and mapping of bovine dopamine receptors 1 and 5

A cDNA encoding the bovine dopamine receptor 1 (DRD1) was isolated from a bovine cDNA library, cloned and completely sequenced. The coding region showed 93 and 91% sequence identity on DNA level and 96 and 94% on protein level with its respective porcine and human orthologs. The bovine DRD1 and dopamine receptor 5 (DRD5) were mapped, respectively, to BTA10 and 6 by radiation hybrid mapping. One SNP was found in DRD1 and four in DRD5. Using polymerase chain reaction-restriction fragment length polymorphism, 11 different European cattle breeds were screened for the presence of the DRD1 and DRD5 substitutions. Allele frequencies for DRD1 and DRD5 alleles were very similar across all the breeds examined. Allele frequency discrepancies were found between Belgian Blue beef breed and the other breeds.

Toward a molecular architecture of personality

Epidemiological studies provided a large body of evidence that personality dimensions are influenced by genetic factors and that the genetic component is highly complex, polygenic, and epistatic. However, consistent findings on the genetic basis of personality have yet remained sparse. In recent years, molecular genetics has begun to identify specific genes coding in particular for components of the serotonergic and dopaminergic neurotransmitter systems representing quantitative trait loci (QTLs) for behavioral traits. The QTL concept suggests that complex traits are not attributable to single genes. According to this polygenic model, the genetic basis of personality and behavior and its pathological variations thus results from additive or nonadditive interactions of various genes. As the number of suitable candidate genes constantly increases, the QTL model provides a reasonable explanation for the genetic basis of personality and its disorders. In this review, the current knowledge on the impact of a large number of candidate gene polymorphisms (e.g. variations in serotonin and dopamine receptor and serotonin transporter genes) on personality and temperament is summarized. Additionally, investigations of gene-gene and gene-environment interactions in humans and animals, which currently intensify the identification of genes that underlie behavioral variations, are examined. The findings converge on the notion that a probabilistic rather than deterministic impact of genes on the expression of behavior will contribute to the demystification of behavioral disorders.

Prevalence of attention deficit/hyperactivity disorder among adults in obesity treatment

BACKGROUND

Bariatric patients showing poor "focus" during treatment more often failed to lose weight or maintain reduced weight. Evaluation of these patients identified a number having attention deficit/hyperactivity disorder (ADHD), evidently a potent factor limiting successful weight control. After searches found no published reports describing comorbid ADHD and obesity, this report was conceived to begin exploring the prevalence and characteristics of these patients.

METHOD

Clinical records of 215 patients receiving obesity treatment during 2000 were reviewed. Data collected and analyzed included age, sex, beginning and ending body mass index (BMI), number of clinic visits, months of treatment, and diagnostic category (ADHD, some ADHD symptoms, non-ADHD). DSM-IV criteria were used, except age of onset was modified to <= 12 years.

RESULTS

Whole sample ADHD prevalence was 27.4% (CI:21.1,32.9), but 42.6% (CI: 36.3% to 48.9%) for BMI >= 40. Mean weight loss among obese patients with ADHD (OB+ADHD) was 2.6 BMI (kg/m2) vs. 4.0 for non-ADHD (NAD) (p < 0.002). For BMI >= 40, OB+ADHD had BMI loss 2.9 vs. 7.0 (NAD) (p < 0.004). OB+ADHD had more clinic visits, with a trend toward longer treatment duration.

CONCLUSIONS

ADHD was highly prevalent among obese patients and highest in those with extreme obesity. Comorbid obesity and ADHD symptoms rendered treatment less successful compared to NAD counterparts. Reasons for the comorbidity are unknown, but may involve brain dopamine or insulin receptor activity. If replicated in further studies, these findings have important implications for treatment of severe and extreme obesity.

Polymorphisms in dopamine receptors: what do they tell us?

Many genetic studies have focussed on dopamine receptors and their relationship to neuropsychiatric disease. Schizophrenia, bipolar disorder, and substance abuse have been the most studied, but no conclusive linkage or association has been found. The possible influence of dopamine receptor variants on drug response has not received as much attention. While there is some evidence that polymorphisms and mutations in dopamine receptors can alter functional activity and pharmacological profiles, no conclusive data link these gene variants to drug response or disease. The lack of unequivocal findings may be related, in part, to the subtle changes in receptor pharmacology that these polymorphisms and mutations mediate. These subtle effects may be obscured by the influence of genes controlling drug metabolism and kinetics. Further insight into the pharmacogenetics of dopamine receptors may require not just more studies, but novel approaches to the study of complex genetic traits and diseases.