Unaffected 1st degree relatives of patients with major depressive disorder (MDD) are more likely to develop MDD than healthy controls. The aim of our study was to establish neuronal correlates of familial susceptibility in the process of inhibition of emotional information. Unaffected 1st degree relatives of patients with MDD (N = 21) and matched healthy controls (N = 25) underwent a functional magnetic resonance imaging procedure with an inhibition task. Blood oxygenated level dependent signal was evaluated for the two groups during inhibition of positive, negative and neutral information. In a 2 × 3 ANOVA unaffected relatives of patients with MDD were compared to healthy controls, jointly and separately for all three levels of emotional valence of the information. The interaction between group and emotional valence of the inhibited information was significant, indicating "a negative neural drift" in unaffected relatives of patients with MDD. The unaffected relatives of patients with MDD displayed an increased activation during inhibiting of negative material in the right middle cingulate cortex and the left caudate nucleus (p < 0.05, family wise error corrected). There was no difference between the two groups in terms of inhibiting positive or neutral stimuli. Our findings provide the first evidence that unaffected relatives of patients with MDD differ from the standard population in terms of neural correlates of inhibition of negative emotional information. Overactivation of cingulate cortex and caudate nucleus may indicate a learnt strategy aimed at coping with increased susceptibility to negative information schemata and may have future consequences for therapy.
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