OBJECTIVE: Amygdala abnormalities have been discussed as a possible mechanism underlying reduced reactivity to negative stimuli in Parkinson's disease (PD).
METHODS The present investigation used functional magnetic resonance imaging (fMRI) in order to test this hypothesis. We compared brain activation of 17 nondepressed and nondemented PD patients with 22 healthy controls during the elicitation of negative affective states. The patients suffered from moderate motor symptoms for an average of 75 months and had stopped their antiparkinson medication 10-12 hours prior to the fMRI testing. All participants were shown images which depicted disgusting, fear-relevant and neutral contents and they answered self-report scales for the assessment of disgust proneness and trait anxiety.
RESULTS: Both groups did not differ from each other in affective state and trait ratings. In line with the self-report, the fMRI data showed similar activation (including the amygdala) in both groups during disgust and fear elicitation.
CONCLUSION: This fMRI investigation found no indication of diminished disgust and fear experience in PD. SIGNIFICANCE: Previously reported affective processing deficits in PD might be due to insufficiently controlled confounding variables (medication, depression, cognitive impairment).