The amygdala in adolescents with attention-deficit/hyperactivity disorder: Structural and functional correlates of delay aversion.

OBJECTIVES

Recent magnetic resonance imaging (MRI) studies implicate structural alterations of amygdala, a brain region responsible for processing and experiencing negative emotions, in adolescents with attention-deficit/hyperactivity disorder (ADHD). Here we examined ADHD-related structural correlates of amygdala functional activity elicited during a functional MRI task designed to test behavioural and brain responses to the imposition of delay - an event known to both elicit amygdala hyperactivation and aversity in ADHD.

METHODS

Structural MRI scans from 28 right-handed male adolescents with combined type ADHD and 32 age-matched controls were analysed. Regional grey matter volumes of ADHD and control participants ([FWE] < 0.05) were correlated with delay aversion self-ratings and neural activity in response to delay-related cues on the Escape Delay Incentive fMRI task.

RESULTS

ADHD was associated with significantly reduced volumes in bilateral amygdala, parahippocampal and temporal gyrus ([FWE] < 0.05), greater basolateral amygdala activation to delay-related cues ([FWE] < 0.05) and higher delay aversion self-ratings. Amygdala volume reductions were significantly correlated with, and statistically mediated the pathway from ADHD to, delay-cue-related amygdala hyperactivity ( < 0.01) and self-reported delay aversion ( < 0.01).

CONCLUSIONS

We provide the first evidence of the functional significance of reduced amygdala volumes in adolescents with ADHD by highlighting its relation to delay-induced brain activity that is linked to delay aversion.