Background: This study investigated biological correlates of depression in patients with idiopathic Parkinson's disease (PD). We tested the hypothesis that in patients with PD and depression, there was regional dysfunction involving brain areas previously implicated in functional imaging studies of patients with primary depression.
Method: Using positron emission tomographic measurements of regional cerebral blood flow (rCBF), patterns of resting rCBF were measured in ten patients with PD and major depression, and ten patients with PD alone. The results were compared with findings from ten patients with primary depression and ten normal controls, scanned using identical methods as part of an earlier study. Groups were matched for age, sex and symptom severity.
Results: Bilateral decreases in rCBF were observed in anteromedial regions of the medial frontal cortex and the cingulate cortex (Brodmann's areas (BA) 9 and 32) in the depressed PD group, compared with those with PD alone and compared with normal controls. This regional disturbance overlapped that observed in patients with primary depression.
Conclusions: The findings indicate that the medial prefrontal cortex is a common area of neural dysfunction in the manifestation of both primary depression and depression in PD.