[Cerebral glucose metabolism in Parkinson's disease with dementia].

Objective: To assess the regional cerebral glucose utilization and the imaging characteristic of Parkinson's disease with dementia (PDD) with (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET).

Methods: Questionnaire survey, mini-mental state examination (MMSE), physical examination, and FDG PET on brain at rest state were performed on 20 patients with PDD, 13 males and 7 females, aged (70 +/- 6), and sex- and age-matched 8 patients with non-demented PD, and 30 healthy parsons. Visual inspection and statistical parametric mapping (SPM) were used to investigate the regional cerebral metabolic rate of glucose (rCMRglc) and the distribution of the tracer.

Results: The MMSE score of the PDD group was (27.5 +/- 2.4), (10 - 24), significantly lower than those of the non-PDD group [(27.5 +/- 2.4) (22 - 30)] and control group [(27.9 +/- 2.2) (21 - 30)] (F = 60.31, P = 0.000). There were no significant differences in Hoehn-Yahr staging and disease courses between the two PD groups (P > 0.05). Visual inspection showed that there were no significant focal hypometabolic areas in the imaging of the non-demented PD patients, while compared to the controls, the rCMRglc levels of the PDD patients decreased in bilateral superior parietal lobules (BA 7), inferior parietal lobules (BA 40, 39), superior frontal gyri (BA 6), middle frontal gyri (BA 6, 8, 9), middle temporal gyri (BA 21), cuneate lobes (BA 17, 18, 19), cingulate cortices (BA 31), lingual gyri (BA 19) basal ganglia, and thalamus. According to the severity of memory impairment and the onset of hallucination, the subtype of PDD was classified into memory impairment dominant group (MD) and hallucination dominant group (HD). The rCMRglc of MD subgroup decreased significantly in the parietotemporal association cortex, especially in the precuneus lobe. The rCMRglc of the HD subgroup decreased significantly in the occipital cortex. There were no significant differences in MMSE score and Hoehn-Yahr staging between the MD and HD groups (both P > 0.05), while the age of the HD subgroup was significantly lower, and the disease duration of the HD subgroup was significantly longer than those toe MD group (both P < 0.05).

Conclusions: (18)F-FDG/PET imaging is helpful to the diagnosis of PDD and may help investigate the potential pathophysiology of PDD.