Neural Mechanisms of Cognition in ADHD and Externalizing Behavior

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DESCRIPTION (provided by applicant): Understanding the neurobiological mechanisms involved in the cognitive deficits associated with externalizing behaviors (EB) has the potential to provide insight into the etiology, symptomatology, and possibilities for prevention and treatment of EB, both subclinically and in disorders such as ADHD, conduct disorder, and antisocial personality disorder. Using imaging genomics, this research will investigate the neural mechanisms involved in cognitive deficits associated with EB, such as impulsivity and aggression. I will focus on the sparing of intelligence (IQ) in individuals with a specific variant of a dopamine receptor, which I have recently discovered in my graduate work. In three samples, a specific variant of the dopamine D4 receptor gene (DRD4) completely attenuated the negative association of EB and IQ (r = .02 vs. r = -0.43). Sixty four participants, screened for the presence of relevant DRD4 variants, will be scanned with fMRI while performing cognitive and affective tasks, and will be assessed for EB, intelligence, and other individual differences. I predict that DRD4 variation will moderate brain activity within dorsolateral and ventrolateral PFC during cognitive and affective challenges, respectively. Related analyses will be done in several existing data sets. Three of these consist of children (incarcerated or diagnosed with ADHD), who have been genotyped for DRD4 polymorphisms, while a fourth consists of healthy adults with fMRI data.