Childhood maltreatment is associated with lower exploration and disrupted prefrontal activity and connectivity during reward learning in volatile environments.

Background: Atypical reward processing is implicated in a range of psychiatric disorders associated with childhood maltreatment and may represent a latent vulnerability mechanism. In this longitudinal study, we investigated the impact of maltreatment on behavioural and neural indices of reward learning in volatile environments and examined associations with future psychopathology assessed 18 months later.

Methods: Thirty-seven children and adolescents with documented histories of maltreatment (MT group) and a carefully matched group of 32 non-maltreated individuals (NMT group) aged 10-16 were presented with a probabilistic reinforcement learning task featuring a phase of stable and a phase of volatile reward contingencies. Brain activation and connectivity were assessed simultaneously using functional magnetic resonance imaging (fMRI). Computational models were used to extract individual estimates of learning rates and temperature, and neural signals in prespecified regions of interest were analysed during volatile and stable environments. In regression analyses, behavioural measures and neural signals at baseline were used to predict psychological symptoms at follow-up.

Results: The MT group showed lower behavioural exploration, which predicted decreased internalising symptoms at follow-up. The MT group had lower activation in the orbitofrontal cortex (OFC) during outcome delivery in volatile relative to stable contexts. OFC connectivity with an area in the mid-cingulate cortex was also lower during outcome processing, which predicted higher general psychopathology at follow-up.

Conclusions: These findings are consistent with the notion that low exploratory behaviour following childhood maltreatment is potentially a protective adaptation against internalising symptoms, while disrupted neural processing of reward learning in volatile environments may index latent vulnerability to mental illness.