Attention-deficit hyperactivity disorder (ADHD) is a clinically complex and multifactorial psychiatric disorder of inattention, hyperactivity and impulsivity. Family, twin and adoption studies suggest a genetic influence in the etiology of ADHD. Two variable number of tandem repeats (VNTR) polymorphic systems have been frequently associated with this disorder: the 7 repeat (R) allele in exon 3 ...

Introduction: Hippocampal neuroanatomy is affected by genetic variations in dopaminergic candidate genes and environmental insults, such as early onset of chronic cannabis exposure. Here, we examine how hippocampal total and subregional volumes are affected by cannabis use and functional polymorphisms of dopamine-relevant genes, including the catechol-O-methyltransferase (COMT), dopamine transp...

OBJECTIVES The purpose of this study was to determine the relationship between sweet-liking phenotype and the variation of the gene sequence of the dopaminergic and serotonergic system. METHODS The study recruited 100 probands. The participants were interviewed for addiction (SSAGA-Semi Structured Assessment for the Genetics of Alcoholism) and assessed with the questionnaires: MMSE, Beck Depr...

Researchers conducting candidate gene studies of attention-deficit/hyperactivity disorder (ADHD) typically obtain symptom ratings from multiple informants (i.e., mothers, fathers, and teachers) and use a psychologist's best estimate or a simple algorithm, such as taking the highest symptom ratings across informants, to construct diagnostic phenotypes for estimating association. Nonetheless, the...

Problems related to food and weight in women may be influenced by the (DA) dopamine system. Catechol-o-methyl transferase (COMT) and the dopamine transporter (DAT) exert control on concentrations of extracellular DA. High and low functioning alleles of the COMT Val158Met and DAT1 3' UTR VNTR polymorphisms have been identified, and their associations with reward and cognition suggest a role in t...

We [Hawi et al. (2005); Am J Hum Genet 77:958-965] reported paternal over-transmission of risk alleles in some ADHD-associated genes. This was particularly clear in the case of the DAT1 3'-UTR VNTR. In the current investigation, we analyzed three new sample comprising of 1,248 ADHD nuclear families to examine the allelic over-transmission of DAT1 in ADHD. The IMAGE sample, the largest of the th...

Serotonin and dopamine are speculated to subserve motivationally opponent functions, but this hypothesis has not been directly tested. We studied the role of these neurotransmitters in probabilistic reversal learning in nearly 700 individuals as a function of two polymorphisms in the genes encoding the serotonin and dopamine transporters (SERT: 5HTTLPR plus rs25531; DAT1 3'UTR VNTR). A double d...

OBJECTIVES To examine the association between polymorphisms in the dopamine transporter gene (SLC6A3, DAT1) and treatment outcome in smokers attempting to quit using either nicotine replacement therapy or bupropion. METHODS The sample consisted of 583 smokers recruited from a smoking cessation clinic, and followed throughout the 4 weeks of post-cessation treatment with behavioural support and...

CONTEXT A distinct pattern of selective attention deficits in attention-deficit/hyperactivity disorder (ADHD) has been difficult to identify. Heterogeneity may reflect differences in underlying genetics. OBJECTIVE To document an objective deficit of selective attention in a large sample of children with and without ADHD using spatial orienting paradigms. By stratifying samples according to th...

Dysfunction in the dopaminergic and serotonergic neurotransmitter systems has been demonstrated to be important in the etiology of borderline personality disorder (BPD). We investigated the relationship of two BPD risk factors, the HTR1A promoter polymorphism -1019C > G (rs6295) and the dopamine transporter (DAT1) repeat allele, with BPD in a major depressive disorder cohort of 367 patients. Ou...