Key result
Acute mild-to-moderate stroke is linked to reduced reward sensitivity and altered frontoparietal connectivity.
Why the study?
Rewards are an important co-factor for learning, but how reward system dysfunction, apathy, and anhedonia affect rehabilitation in stroke patients remains unclear.
Is acute mild to moderate stroke associated with reward network dysfunction and cognitive impairment compared to healthy controls?
Case-Control (n=54)
No
Is acute mild to moderate stroke associated with reward network dysfunction and cognitive impairment compared to healthy controls?
Mean Difference: 8.61
p-value: p=0.021
Acute mild to moderate stroke is associated with reward network dysfunction and reduced learning capacity, highlighting the need for individualized recovery exercises in rehabilitation.
May indicate motivational deficits affecting stroke recovery; hypothesis-generating and requires prospective validation before clinical adoption.
Stroke survivors not only suffer from severe motor, speech and neurocognitive deficits, but in many cases also from a "lack of pleasure" and a reduced motivational level. Especially apathy and anhedonic symptoms can be linked to a dysfunction of the reward system. Rewards are considered as important co-factor for learning, so the question arises as to why and how this affects the rehabilitation of stroke patients. We investigated reward behaviour, learning ability and brain network connectivity in acute (3-7d) mild to moderate stroke patients (n = 28) and age-matched healthy controls (n = 26). Reward system activity was assessed using the Monetary Incentive Delay task (MID) during magnetoencephalography (MEG). Coherence analyses were used to demonstrate reward effects on brain functional network connectivity. The MID-task showed that stroke survivors had lower reward sensitivity and required greater monetary incentives to improve performance and showed deficits in learning improvement. MEG-analyses showed a reduced network connectivity in frontal and temporoparietal regions. All three effects (reduced reward sensitivity, reduced learning ability and altered cerebral connectivity) were found to be closely related and differed strongly from the healthy group. Our results reinforce the notion that acute stroke induces reward network dysfunction, leading to functional impairment of behavioural systems. These findings are representative of a general pattern in mild strokes and are independent of the specific lesion localisation. For stroke rehabilitation, these results represent an important point to identify the reduced learning capacity after stroke and to implement individualised recovery exercises accordingly.
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Wagner et al. (2023) conducted a case-control in Acute mild to moderate stroke (n=54). Acute mild to moderate stroke vs. Age-matched healthy controls was evaluated on Interaction effect between low reward cue (3ct) and subject group (stroke vs. healthy controls) on reaction time (m = 8.61, p=0.021). Acute mild to moderate stroke was associated with significantly reduced reward sensitivity to low monetary incentives and altered functional connectivity in frontal and temporoparietal brain regions compared to healthy controls.
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