F070 Reward processing and prediction deficits in Huntington’s disease: implications for behavioral maladjustment and disease monitoring

<h3>Background</h3> The brain systems involved in encoding reward-related signals and in reward prediction are compromised in Huntington’s disease (HD). Few studies have explored the integrity of these processes and their impact on behavior. <h3>Methods</h3> 49 gene mutation carriers (preHD: n=21; HD: n=28) and 21 controls were recruited. We designed a decision-making task based on two blocks during which subjects choose one of two options (5 vs 25) receiving feedback (gain vs loss) after selection. Probability of gain/loss was set at 50% in block 1, and at 75% in block 2. EEG was recorded at 26 locations to later study the morphology of the feedback-related negativity (FRN), the readiness potential (RP) and the stimulus preceding negativity (SPN), all measures related to reward processing and anticipation. Linear-regression models were built to explore the learning profile. <h3>Results</h3> The maintenance of learning along trials was deficient in preHD and HD compared to controls. In HD, a dramatic abolition of the FRN was observed and associated with the severity of perseveration and apathy. The RP and the SPN -as indices of reward anticipation- were both reduced in preHD and HD and associated with a deficient learning slope, the severity of apathy and perseveration figure 1. <h3>Conclusion</h3> The earliest stages of reward processing are profoundly altered in HD and this has a clear effect on the expression of perseverative behavior and apathy. Already in the preHD stage there is a deficiency in anticipating consequences that is observed both at the neurophysiological level and in the learning curve.