Proton Magnetic Resonance Spectroscopy Changes in Parkinson's Disease With and Without Psychosis.

BACKGROUND: Psychosis prevalence in Parkinson's disease is estimated at 8-30%. Proton magnetic resonance spectroscopy measures specific metabolites as markers of cell functioning. OBJECTIVE: To study N-acetyl-aspartate and glutamate levels in the caudate and putamen nuclei in subjects with Parkinson's disease with and without psychosis. METHODS: We included 20 non-demented Parkinson's disease patients with psychosis and 20 Parkinson's disease patients without psychosis matched for age, sex, disease duration, and levodopa equivalent daily dose, all attended at an academic medical center. Proton magnetic resonance spectroscopy scans were performed in a 3T GE whole-body scanner. RESULTS: Decreased glutamate levels scaled to creatine were found in the dorsal caudate (p = 0.005) and putamen (p = 0.007) of the Parkinson's disease psychosis group compared with the without psychosis group. Glutamate plus glutamine levels scaled to creatine and N-acetyl-aspartate levels scaled to creatine were also significantly reduced in the dorsal caudate of the Parkinson's disease with psychosis group (p = 0.018 and p = 0.011, respectively). No group differences were found for any of the other metabolites in the two regions of interest. CONCLUSIONS: Our findings suggest that decreased metabolite levels in specific brain areas may be implicated in the development of psychosis in Parkinson's disease.