Effort-based decision-making, reward, and dopamine in depression in Parkinson’s disease

Parkinson's disease is the fastest-growing neurodegenerative condition globally. Depression is common in Parkinson’s affecting up to a third of patients.

However, our understanding of the underlying causes of depression in Parkinson’s is poor and current treatments are ineffective.

My project aims to identify whether dopamine-dependent difficulties in decision-making are a cause of depression in Parkinson's.

I will recruit four groups of participants; Parkinson's patients with and without depression, patients with depression without Parkinson's, and healthy controls.

Participants will complete a computerised task that measures how much effort they are willing to expend for a potential reward.

Difficulties with this kind of decision-making are a core component of loss of motivation and interest in pleasurable experiences, both common symptoms in depression and Parkinson's.

Parkinson's patients will complete the task on and off their dopamine medications while having their brain scanned, enabling analysis of dopamine’s role in depression and decision-making in Parkinson's and the brain regions involved.

This study will improve our understanding of depression in Parkinson's and whether it differs from depression in people who don't have Parkinson's.

It could also help identify effective treatments, such as a role for dopamine targeting antidepressants or psychological therapy focusing on motivation and decision-making.