Alzheimer's disease pathology frequently coexists with
Lewy body disease at autopsy in patients with probable
dementia with Lewy bodies. More than half of patients with probable
dementia with Lewy bodies have high
amyloid-β deposition as measured with 11C-Pittsburgh compound B binding on positron emission tomography.
Biomarkers of
amyloid-β deposition precede neurodegeneration on magnetic resonance imaging during the progression of
Alzheimer's disease, but little is known about how
amyloid-β deposition relates to longitudinal progression of
atrophy in patients with probable
dementia with Lewy bodies. We investigated the associations between baseline 11C-Pittsburgh compound B binding on positron emission tomography and the longitudinal rates of grey matter
atrophy in a cohort of clinically diagnosed patients with
dementia with Lewy bodies (n = 20), who were consecutively recruited to the Mayo Clinic
Alzheimer's Disease Research Centre. All patients underwent 11C-Pittsburgh compound B positron emission tomography and magnetic resonance imaging examinations at baseline. Follow-up magnetic resonance imaging was performed after a mean (standard deviation) interval of 2.5 (1.1) years. Regional grey matter loss was determined on three-dimensional T1-weighted magnetic resonance imaging with the tensor-based morphometry-symmetric normalization technique. Linear regression was performed between baseline 11C-Pittsburgh compound B standard unit value ratio and longitudinal change in regional grey matter volumes from an in-house modified atlas. We identified significant associations between greater baseline 11C-Pittsburgh compound B standard unit value ratio and greater grey matter loss over time in the posterior cingulate gyrus, lateral and medial temporal lobe, and occipital lobe as well as caudate and putamen nuclei, after adjusting for age (P < 0.05). Greater baseline 11C-Pittsburgh compound B standard unit value ratio was also associated with greater ventricular expansion rates (P < 0.01) and greater worsening over time in Clinical Dementia Rating Scale, sum of boxes (P = 0.02). In conclusion, in patients with probable
dementia with Lewy bodies, higher
amyloid-β deposition at baseline is predictive of faster neurodegeneration in the cortex and also in the striatum. This distribution is suggestive of possible interactions among
amyloid-β, tau and α-
synuclein aggregates, which needs further investigation. Furthermore, higher
amyloid-β deposition at baseline predicts a faster clinical decline over time in patients with probable
dementia with Lewy bodies.