Neuritic Pathology as a Correlate of Synaptic Loss in Dementia With Lewy Bodies

Abstract

Synaptic loss is present in Alzheimer's disease and correlates with the severity of dementia. Loss of synapses in dementia with Lewy bodies (DLB) does not correlate as clearly with cognitive status and its cause is unclear. To begin to understand the relationship between cognition and synaptic loss in DLB, we assessed immunoreactivity for the synaptic-terminal specific protein, synaptophysin, in the hippocampus in 14 DLB cases. Quantitative synaptic data were obtained using an Image-Pro semiautomated analysis system. We determined Braak stage, β-amyloid, Lewy bodies (LBs), and Lewy neurites (LN). We found significant correlations ( r = 0.617, P < .01) between Braak stage and synaptophysin score and marginal correlation between LN score and synaptophysin loss ( r = 0.694, P < .06). Correlations of β-amyloid and of LB density with synaptophysin score were unimpressive. These data support the hypothesis that synaptic loss in DLB is related to neuritic degeneration.