Primary visual cortical metabolism and rapid eye movement sleep behavior disorder in dementia with Lewy bodies

Aim: Significant glucose hypometabolism in the primary visual cortex (PVC) is considered to support a diagnosis of dementia with Lewy bodies (DLB), but its relationship to the clinical features remains unknown. The purpose of this study was to assess the association between the metabolic pattern and clinical variables in DLB.

Methods: A total of 27 DLB patients who underwent [18F]fluoro-d-glucose (18F-FDG) positron emission tomography scans were examined. Demographics and clinical variables were compared between patients with and without glucose hypometabolism in the PVC. The correlations between the cerebral metabolic rate of glucose in the PVC and clinical variables were also investigated.

Results: Only the onset age of probable rapid eye movement sleep behavior disorder (RBD) was significantly different between patients with and withoutglucose hypometabolism in the PVC, being younger in patients with the metabolic pattern; there were no other differences in clinical variables. The onset age of probable RBD was significantly correlated with the cerebral metabolic rate of glucose in the PVC.

Conclusions: Glucose hypometabolism in the PVC provides a potential mechanism for the link between antecedent RBD and the subsequent development of dementia in DLB patients. Glucose hypometabolism in the PVC may represent the effect of the pathophysiological process of DLB on RBD rather than a distinct condition in the disease progression. The physiological aspects of the link between this metabolic pattern and the onset of RBD remain unclear.