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OBJECTIVE: The primary purpose of this study was to confirm the association of a specific haplotype of the dopamine transporter gene and attention deficit hyperactivity disorder (ADHD), which could be one source of the heterogeneity seen across published studies. METHOD: The authors previously reported the association of ADHD with a subgroup of chromosomes containing specific alleles of two variable-number tandem repeat polymorphisms within the 3' untranslated region and intron 8 of the dopamine transporter gene. They now report on this association in a sample of ADHD combined-type probands. RESULTS: The original observations were confirmed, with an overall odds ratio of 1.4 across samples. CONCLUSIONS: These data challenge results of meta-analyses suggesting that dopamine transporter variation does not have an effect on the risk for ADHD, and they indicate that further investigation of functional variation in the gene is required. [ABSTRACT FROM AUTHOR]

Objective: Maternal depression across the postbirth period has long-term negative consequences for infant development. Little is known of the neurobiological underpinnings, but they could involve oxytocin, a neuropeptide that is dysfunctional in depression and is implicated in birth and parenting., Method: The authors recruited a community cohort of women with high or low depression scores 2 days after childbirth and measured depression again at 6 and 9 months. When the child was 6, the authors evaluated the families of 46 chronically depressed mothers and 103 mothers reporting no depression since childbirth. The child was assessed for psychiatric diagnoses, social engagement, and empathy. Mother, father, and child were tested for salivary oxytocin level and variation in the rs2254298 single nucleotide polymorphism on the OXTR gene., Results: Of the children of the chronically depressed mothers, 61% displayed axis I disorders, mainly anxiety and oppositional defiant disorder, compared with 15% of the children of nondepressed mothers. In the depressed mothers' families, salivary oxytocin was lower in mothers, fathers, and children, and the children had lower empathy and social engagement levels. The rs2254298 GG homozygous genotype was overrepresented in depressed mothers and their families, and it correlated with lower salivary oxytocin. Presence of a single rs2254298 A allele (GA or AA genotype) in depressed mothers markedly decreased risk of child psychopathology., Conclusions: The negative effect of chronic maternal depression on child social outcomes was related to genetic and peripheral biomarkers of the oxytocin system. This suggests a potential for oxytocin-based interventions.

Objective: An interesting candidate gene for eating disorders is the gene for insulin-like growth factor 2 (IGF2). Located on chromosome 11p15.5, IGF2 is a member of the insulin family of polypeptide growth factors that is involved in development and growth. Consistent with its profile of metabolic actions, an association has been reported between a single nucleotide polymorphism (SNP) in the 3' untranslated region of the IGF2 gene (ApaI) and body mass index. This investigation extended these studies and investigated the psychological and behavioral implications of this hormone's impact on metabolism and body composition., Method: The authors tested nonclinical subjects from 376 families for three IGF2 SNPs and for eating disorders, as reflected in scores on the 26-item Eating Attitudes Test, a self-report questionnaire widely used as a screening instrument., Results: A highly significant association was observed between the IGF2 ApaI G allele and scores on the Eating Attitudes Test overall and each of its subscales (bulimia, dieting, and oral control). Additionally, a significant association was observed between this polymorphism and body mass index., Conclusions: The current finding that the IGF2 ApaI G polymorphism, which predisposes to weight gain, may also contribute to the pathology of eating disorders is intriguing. Neurotransmitter modulation of appetitive behavior is the focus of most hypotheses regarding the etiology of severe eating disorders. The current results to some measure challenge this view, and inborn metabolic tendencies to weight gain in some women may trigger constant dieting, which in predisposed individuals eventually leads to severe eating disorders.

Objective: In an ongoing molecular genetic study of temperament, participants were genotyped to examine the association of smoking with two polymorphisms of the serotonin transporter gene (SERT): the promoter region, 5-HTTLPR, and an intronic variable-number-of-tandem-repeats region (VNTR)., Method: Full information was available for 330 families, and 244 "ever smokers" were identified (54 past smokers, 190 current smokers). The average number of cigarettes smoked per day was 13.12, and the mean Fagerstrom Tolerance Questionnaire score was 4.79. Associations of genotype, Tridimensional Personality Questionnaire scores, and smoking phenotype were tested by using a robust family design with a variance-components framework and by case-control analysis., Results: There was a significant excess of the 5-HTTLPR long allele with the 12-repeat VNTR in current smokers, past smokers, and ever smokers, compared to participants who had never smoked. The results from the population design were confirmed in the family-based analysis. No association was observed between two quantitative measures of smoking and the polymorphisms. A weak association was observed between novelty seeking and the VNTR polymorphism and between reward and 5-HTTLPR. Smokers, regardless of gender, scored significantly higher on novelty seeking and did not differ on harm avoidance or reward., Conclusions: There was a highly significant association between SERT and the categorical definition of smoking, irrespective of dependence level, suggesting that this gene influences the initiation of smoking. Mediation analysis failed to substantiate the hypothesis that novelty seeking partially mediates the effect of SERT on smoking. SERT appears to independently contribute to novelty seeking and smoking.

Objective: Studies have shown that genetic factors are significant in predisposing individuals to shyness and social phobia. Toward further elucidating the genetic structure of shyness, the authors examined four functional polymorphisms that make biological sense for contributing to the development of this phenotype: serotonin transporter promoter region 44 base pair insertion/deletion (5-HTTLPR), dopamine D(4) receptor exon III repeat (DRD4), catechol O-methyltransferase (COMT), and monoamine oxidase A promoter region repeat (MAO(A))., Method: The authors assessed shyness after recruitment of a nonclinical sample (N=118, unscreened second-grade children) using a composite scale derived from questionnaires administered to the children, parents, and teachers. DNA from buccal smears successfully obtained from 98 children was genotyped by polymerase chain reaction methods for the 5-HTTLPR, DRD4, COMT, and MAO(A) polymorphisms., Results: Significant correlations were observed for parents', teachers', and children's ratings of shyness, and Cronbach's alpha reliability was high for all three scales. A significant association was observed between the long 5-HTTLPR polymorphism and shyness, both by the functional classification of Lesch as well as by consideration of all three genotypes. No significant association was observed for the DRD4, COMT, or MAO(A) polymorphisms., Conclusions: This study provisionally identifies a common genetic polymorphism, 5-HTTLPR, that modestly (effect size=7%) contributed to greater shyness scores in a nonclinical group of second-grade students. These first findings may be relevant to previous reports that have shown an association between the 5-HTTLPR long form and obsessive-compulsive disorder and autism.

Cyclic adenosine 3',5'-monophosphate (cAMP) signal transduction was examined in lymphocytes and platelets obtained from patients with posttraumatic stress disorder. Intact lymphocytes from the posttraumatic patients (N = 10) showed significantly lower basal, isoproterenol-, and forskolin-stimulated cAMP levels than those from 10 healthy control subjects. In platelet membrane preparations, basal, forskolin-, aluminum chloride plus sodium fluoride-, and prostaglandin E1-stimulated adenylate cyclase activity levels were all significantly lower in the posttraumatic group than in the control group. The authors discuss the potential role of their findings as a biological marker for posttraumatic stress disorder.

Heart rate rises associated with performance of mental arithmetic tasks were compared in 22 euthymic manic-depressive patients receiving lithium carbonate and 17 drug-free normal controls. The lithium-treated subjects showed a markedly lower heart rate response to the mental arithmetic stimulus. No effect was observed on basal heart rate. The results are consistent with lithium's reported inhibition of noradrenaline-induced rises in adenylate cyclase activity but lack of inhibition of basal adenylate cyclase activity. The biochemical and psychophysiological findings may parallel lithium's unique ability to calm excited behavior without sedating normal behavior.