P 10 The effect of post-stroke depression and motor impairment on incentive motivation

Abstract

Background: Stroke is a common cause of permanent motor disability, but also results in post-stroke depression (PSD). Understanding the relationship between motor impairment and motivational symptoms of PSD may further improve rehabilitation post-stroke. Method: We used a monetary incentive grip force task including high and low rewards in 17 acute stroke in-patients and 23 healthy participants. Motor and PSD scores were assessed early after stroke. PSD symptoms were re-assessed at 6 months post-stroke. We used frequency analyses to investigate underlying effects of incentive motivation on grip force oscillations. Finally, we analyzed the association between structural lesions of corticostriatal tracts and incentive motivation. Results: Both groups showed incentive motivation in terms of higher grip force for high versus low reward trials. Nevertheless, in stroke patients, the effect of motivation on grip performance depended on both, the level of motor impairment and PSD symptoms at early and later stages. Severely impaired patients showed stronger incentive motivation and were less likely to develop motivational PSD symptoms. Early depressive symptoms were associated with less monetary outcome due to overall reduced motivation to engage in task performance. Overall, impaired incentive motivation resulted particularly from reduced power at low frequencies (4-7 Hz), correlated with lesions of ventral and dorsal corticostriatal tracts, and predicted PSD symptoms at 6 months post-stroke. Conclusion: Incentive motivation after stroke is modulated by several factors . PSD and lesions of cortico-striatal tracts diminish incentive motivational behavior. In contrast, severe motor impairment represents a motivating factor to engage into motor effort and reduces the risk of PSD at later stages. Likewise, incentive motivation early after stroke appears to prevent later PSD. Acute interventions should address motivational aspects of behavior to improve motor rehabilitation.