Glucose hypometabolism and neuropathological correlates in brains of dementia with Lewy bodies

Cerebral glucose metabolism using positron emission tomography (PET) with F -18-fluorodeoxyglucose was examined in 11 patients with probable Alzheimer' s disease (AD), 6 patients with probable, and 1 patient with autopsy-confir med dementia with Lewy bodies (DLB) as well as in 10 age-matched normal con trol subjects, Among widespread cortical regions showing glucose hypometabo lism in the DLB group, the metabolic reduction was most pronounced in the v isual association cortex compared to that in the AD group, Using a metaboli c ratio of 0.92 in the visual association cortex as a cutoff (mean-2 SD of normal control subjects), DLB could be distinguished from AD with a sensiti vity of 86% and a specificity of 91%, In contrast, apolipoprotein E4 allele frequency and cerebrospinal fluid tau levels did not differ significantly between the two groups. In order to further dissect out neuropathological c orrelates of the dysfunctional occipital lobe, postmortem brains from 19 pa tients with AD and 17 with DLB as well as 11 brains from normal controls we re examined. A distinct and extensive spongiform change with coexisting gli osis was variably noted throughout cerebral white matter with relative spar ing of gray matter in DLB, Notably, the white matter spongiform change and gliosis was most prominently and consistently found in the occipital region of DLB, and the severity of the spongiform change in each brain region gen erally paralleled to the regional difference in reduced glucose metabolism between the living AD and DLB patients. These findings suggest that (1) amo ng several potential antemortem biomarkers in the diagnosis of DLB, measure s of the glucose metabolism in the occipital cortex may be an informative d iagnostic aid to distinguish DLB from AD; and (2) a pathological process th at generates widespread spongiform change and gliosis in long projection fi bers may contribute, at least in part, to the characteristic imaging featur es of DLB. (C) 2000 Academic Press.