Preserved hippocampal function during learning in the context of risk in adolescent suicide attempt

Impairment in decision-making is frequently observed in suicide attempters. Little is known, however, about neural circuitry underlying decision-making in adolescent attempters. Functional magnetic resonance imaging (fMRI) was used to assess decision-making and learning-related neural activity during Iowa Gambling Task (IGT) performance in adolescents with depression and suicide attempt (ATT, n=15), non-attempters with depression (NAT, n=14), and healthy controls (HC, n=13). ATT performed best on the IGT. A three group by two condition (high-risk versus low-risk) by three IGT block (each of 20 cards) whole-brain analysis (p<0.05, corrected) interaction was found in the left hippocampal, frontal and temporal cortical, striatal and thalamic regions. Post-hoc analyses revealed that during low-risk decisions in blocks 2 and 3, NAT, but not ATT, showed greater left hippocampal activation versus HC (p=0.0004, p=0.003); in block 2, during low-risk decisions NAT showed greater left middle temporal gyral activation versus HC (p=0.003); in block 3, during high-risk decisions ATT showed less activation in the right thalamus versus NAT (p=0.001) and during low risk decisions ATT showed greater activation than HC in the left caudate (p=0.002). NAT, but not ATT are differentiated from HC during performance of the IGT. Functional abnormalities in neural circuitry implicated in learning in the context of risk may underlie risk for MDD, but not risk for suicide attempt, in adolescence.