Misinterpreting emotional expressions in ADHD: Evidence for a neural marker and stimulant effects.

Williams LM Hermens DF, Palmer D, Kohn M, Clarke S, Keage H, Clark CR, Gordon E (in press). Misinterpreting emotional expressions in ADHD: Evidence for a neural marker and stimulant effects, Biological Psychiatry, , -.

Background: In addition to cognitive impairment, there are disruptions to mood and emotion processing in attention deficit hyperactivity disorder (ADHD), but little is known about their neural basis. We examined ADHD disturbances in mood and emotion recognition, and underlying neural systems, before and after treatment with stimulant medication. 

Methods: Participants were 51 unmedicated ADHD adolescents and 51 matched healthy controls, rated for depressed and anxious mood and recognition accuracy for facial expressions of basic emotion. Brain function was recorded using event-related potentials (ERPs) while subjects viewed these expressions. ADHD subjects were retested after four weeks, following treatment with methylphenidate (MPH).

Results: ADHD subjects showed a profile of emotion-related impairment: higher depression and anxiety, deficits in recognizing threat-related emotional expressions in particular, and alterations in ERPs. There was a pronounced reduction in occipital activity during the early perceptual analysis of emotional expression (within 120ms), followed by an exaggeration of activity associated with structural encoding (120-220ms) and subsequent reduction and slowing of temporal brain activity subserving context processing (300-400ms). MPH normalized neural activity and produced some improvement of emotion recognition, but had no impact on negative mood. Improvements in neural activity with MPH were consistent predictors of improvement in clinical features of emotional lability and hyperactivity.

Conclusions: Objective behavioral and brain function measures of emotion processing may provide a valuable addition to the clinical armamentarium for assessing emotional disturbances in ADHD and the efficacy of stimulants for treating these disturbances.