Virginie-Anne Chouinard | Search PubMed

PubMed2005

Attention-deficit/hyperactivity disorder endophenotypes.

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable disorder with a multifactorial pattern of inheritance. For complex conditions such as this, biologically based phenotypes that lie in the pathway from genes to behavior may provide a more powerful target for molecular genetic studies than the disorder as a whole. Although their use in ADHD is relatively new, such "endophenotypes" have aided the clarification of the etiology and pathophysiology of several other conditions in medicine and psychiatry. In this article, we review existing data on potential endophenotypes for ADHD, emphasizing neuropsychological deficits because assessment tools are cost effective and relatively easy to implement. Neuropsychological impairments, as well as measures from neuroimaging and electrophysiological paradigms, show correlations with ADHD and evidence of heritability, but the familial or genetic overlap between these constructs and ADHD remains unclear. We conclude that these endophenotypes will not be a quick fix for the field but offer potential if careful consideration is given to issues of heterogeneity, measurement and statistical power.

Adoption↗

PubMed2005

Absence of gender effects on attention deficit hyperactivity disorder: findings in nonreferred subjects.

OBJECTIVE: In a previous study, the authors found that, compared with referred boys with attention deficit hyperactivity disorder (ADHD), girls are less likely to manifest comorbid disruptive behavior disorders and learning disabilities--characteristics that could adversely affect identification of ADHD in girls. However, because referral bias can affect outcome, these findings require replication in nonreferred groups of ADHD subjects. METHOD: The authors evaluated gender effects in a large group of nonreferred siblings (N=577) of probands with ADHD and non-ADHD comparison subjects. Ninety-eight of the nonreferred siblings (N=73 males, N=25 females) met the criteria for diagnosis of ADHD, and 479 (N=244 males, N=235 females) did not meet those criteria. All siblings were systematically and comprehensively assessed with measures of emotional, school, intellectual, interpersonal, and family functioning. The assessment battery used for the siblings was the same as that used for the probands. RESULTS: The nonreferred males and females with ADHD did not differ in DSM-IV subtypes of ADHD, psychiatric comorbidity, or treatment history. They also showed similar levels of cognitive, psychosocial, school, and family functioning. CONCLUSIONS: These findings suggest that the clinical correlates of ADHD are not influenced by gender and that gender differences reported in groups of subjects seen in clinical settings may be caused by referral biases.

Adolescent↗