Cerebral Metabolic Differences Associated with Cognitive Impairment in PD

Glucose metabolism associated with different cognitive states in Parkinson’s disease (PD).

PD-MCI patients exhibited limited areas of hypometabolism in the frontal, temporal and para-hippocampal gyrus compared with the PD-NC pat-Hients (p < 0.01). PDD patients had bilateral areas of hypometabolism in the frontal and posterior parietal-occipital lobes compared with PD-MCI patients (p < 0.01), and exhibited greater metabolic reductions in comparison with PD-NC patients (p < 0.01). Hypometabolism was much higher in the PDD patients than in PD-MCI patients.

Group comparison of regional metabolic changes between PD groups utilizing voxel-based 

statistical parametric mapping analysis.

Metabolic increases are displayed using a red–yellow scale and declines are displayed using a blue–purple scale. Both displays were superimposed on a single-subject MRI brain template and thresh holded at p = 0.01 (uncorrected). (A) PD-MCI VS. PD-NC, (B) PDD VS. PD-MCI, (C) PDD VS. PD-NC.

The cognitive domains affected in PD-MCI patients were as follows: 1 patient (5%) had only the attention domain affected; 7 patients (35%) had two domains affected; 7 patients (35%) had three domains affected; 4 patients (20%) had four domains affected; and 1 patient (5%) had five domains affected.

PDD group had FDG uptake reduction in the right superior frontal gyrus, left precentral gyrus, left parietal lobule, right angular gyrus, left supra-marginal gyrus, left precuneus and cuneus, associated with increased metabolism in the left cingulate gyrus compared with PD-MCI group (p < 0.01). 

PDD patients exhibited more widespread hypometabolism, mainly located in the posterior parietal-occipital regions, compared with PD-MCI patients, and exhibited greater metabolic reductions in comparison with cognitively unimpaired PD patients.

Hypometabolism has been detected in the posterior cingulate, parietal, and temporal association regions, with a lesser involvement of the frontal cortex, when compared with nondemented PD patients. The PDD subjects in this study also had significantly hypometabolism involving the frontal lobes compared with PD-MCI patients. A recent study found that hypometabolism exceeds atrophy in some brain regions in PD patients with cognitive impairment.

Detected the hypometabolism predominantly in the frontal and temporal cortices in PD-MCI patients compared with PD-NC patients.