Inhibition as a marker for a familial subgroup of attention deficit hyperactivity disorder

grantor: University of Toronto'Objective': To investigate whether deficient inhibitory control, as measured by the Stop-Signal Paradigm, delineates a more homogeneous subgroup of Attention Deficit Hyperactivity Disorder (ADHD). 'Method ': Subjects were 54 ADHD children defined as having poor or good inhibition based on performance on the SSP. Poor and Good inhibition groups were compared on family history for ADHD, and measures of neurobiological and psychosocial risk. 'Results': a significantly higher rate of family history for ADHD was found in the Poor (48.1%) versus the Good (18.5%) inhibition group. No differences were found between the groups on index measures of neurobiological or psychosocial risk. 'Conclusions': findings provide preliminary evidence that classification using inhibition delineates a familial subtype of ADHD. No evidence was found that psychosocial or neurobiological factors accounted for the ADHD in the good inhibition group, or that environmental risks and inhibition act conjointly to increase the risk for ADHD in the Poor inhibition group.M.A