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Reward learning deficits in Parkinson's disease depend on depression
M H M Timmer1, G Sescousse1, M E van der Schaaf1
1Donders Institute for Brain,Cognition and Behaviour,Centre for Cognitive Neuroimaging,Radboud University,Nijmegen,The Netherlands.
Psychological Medicine
|April 5, 2017
Summary
Depression in Parkinson's disease (PD) impairs reversal learning and striatal signaling, regardless of dopaminergic medication. These findings highlight the impact of depression on cognitive function in PD patients.
Area of Science:
- Neuroscience
- Cognitive Science
- Neurology
Background:
- Depression is a common and severe non-motor symptom in Parkinson's disease (PD).
- The underlying neurocognitive mechanisms of depression in PD are not well understood.
- Current treatments for depression in PD are frequently suboptimal.
Purpose of the Study:
- To investigate the role of striatal dopamine in reversal learning.
- To examine reward and punishment processing in individuals with and without depression and Parkinson's disease.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to assess brain activity.
- A medication withdrawal procedure was employed.
- Reversal learning tasks involving reward and punishment were administered to 22 non-depressed PD patients and 19 PD patients with a history of depression.
Main Results:
- Parkinson's disease patients with depression (or a history thereof) showed deficits in reversal learning from reward versus punishment.
- These patients also exhibited reduced reward/punishment-related blood-oxygen-level-dependent (BOLD) signals in the striatum (putamen).
- No significant effects of dopaminergic medication were detected on these measures.
Conclusions:
- Impaired reversal learning and associated striatal signaling in Parkinson's disease are linked to the presence of depression.
- These cognitive and neural alterations appear dependent on a history of depression in PD patients.