title: Attention-deficit/hyperactivity disorder endophenotypes.
abstract: 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.
authors.affiliation: Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA. doylea@helix.mgh.harvard.edu
authors.forename: Alysa E
authors.initials: AE
authors.lastname: Doyle
authors.forename: Erik G
authors.initials: EG
authors.lastname: Willcutt
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Seidman
authors.forename: Joseph
authors.initials: J
authors.lastname: Biederman
authors.forename: Virginie-Anne
authors.initials: VA
authors.lastname: Chouinard
authors.forename: Julie
authors.initials: J
authors.lastname: Silva
authors.forename: Stephen V
authors.initials: SV
authors.lastname: Faraone
mesh_terms: D000300:Adoption; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D003952:Diagnostic Imaging; D005071:Evoked Potentials; D005190:Family; D020022:Genetic Predisposition to Disease; D006801:Humans; D008967:Molecular Biology; D009483:Neuropsychological Tests; D011340:Problem Solving; D017447:Receptors, Dopamine D1 / Q000235:genetics; D050641:Receptors, Dopamine D5; D017470:Receptors, Glutamate / Q000235:genetics; D018433:Twin Studies as Topic
chemical_list: C493605:DRD5 protein, human; D017447:Receptors, Dopamine D1; D017470:Receptors, Glutamate; D050641:Receptors, Dopamine D5