Glucose hypometabolism in primary visual cortex is commonly associated with clinical features of dementia with Lewy bodies regardless of cognitive conditions

Background: Although metabolic reduction in the primary visual cortex on [(18) F]-fluoro-d-glucose (FDG) positron emission tomographic (PET) scans is the hallmark of dementia with Lewy bodies (DLB) for differential diagnosis from Alzheimer's disease, the clinical significance of the metabolic pattern in patients without dementia remains unknown. The purpose of this study was to investigate the clinical profiles of patients without dementia with the metabolic pattern and its relevance to DLB.

Methods: Of 145 individuals who underwent (18) F-FDG PET, 25 patients with glucose hypometabolism in the primary visual cortex were identified based on three-dimensional stereotactic surface projection images through comparison with a normative database. The frequency of core and suggestive clinical features of DLB was compared between the groups with and without the metabolic pattern.

Results: Of 25 patients with glucose hypometabolism in the primary visual cortex, 12 exhibited more than two core features of DLB (probable DLB group) and 6 had rapid eye movement sleep behavior disorder (possible DLB group). Three patients exhibited memory loss without any core or suggestive features but with reduced cardiac iodine-123 metaiodobenzylguanidine uptake. Ten of these 21 patients exhibited no dementia. The proportion of individuals in the probable and possible DLB groups was significantly higher in the group with glucose hypometabolism in the primary visual cortex.

Conclusion: Glucose hypometabolism in the primary visual cortex is commonly associated with the clinical features of DLB regardless of cognitive conditions. Continued follow-up of these patients without dementia with the metabolic pattern is warranted to determine if they represent the prodromal state of DLB.