Title: P3-054: Hippocampal sclerosis in the population: Representative adult changes in thought study-prevalence and relationship to other common neuropathologies of aging
Abstract: 85% of the population-attributable risk of dementia in the Adult Changes in Thought (ACT) study cohort was due to 3 common neuropathologies: Alzheimer's disease (45%), microvascular ischemic injury (30%) disease and Lewy body disease (10%). Hippocampal sclerosis (HS) is a less common neuropathology thought to underlie age-related cognitive impairment and dementia. It has been suggested that HS is related to other pathologic processes, specifically Alzheimer's disease or vascular disease. Our objective was to determine the prevalence of HS within our autopsy cohort and determine whether HS correlated with other neuropathologies. 323 consecutive autopsy cases from ACT, an ongoing, community-based, longitudinal study of brain aging and cognitive decline, were evaluated. Subjects were ACT participants 65 years or older who were cognitively intact at the time of enrollment in the Group Health Cooperative in King County, Washington. Hippocampi were sampled in the coronal plane at the level of the uncus and the lateral geniculate body. Sections were stained with Hematoxylin & Eosin - Luxol fast blue stained and evaluated by a board certified Neuropathologist. HS was defined as marked neuronal loss and gliosis in the CA-1 region and subiculum of the hippocampus. The sample set was evaluated for associations between clinical diagnosis of dementia and multiple neuropathological findings using pairwise correlation analysis. Complete neuropathologic evaluations were available on 309 cases. Of these cases, there were 14 (4.5%) with complete HS. 6 individuals with HS were clinically diagnosed with dementia. Clinical dementia status was not significantly correlated with postmortem pathologically diagnosed HS. 7 of the cases with HS occurred in the setting of Braak stage V or VI. HS correlated with high Braak stage (p > 0.05), but not with any other neuropathology. Complete HS was relatively rare in our cohort, but occurred in the setting of high Braak stage more often than would be predicted by chance alone. HS was not a strong correlate of dementia. These findings suggest that HS may be related to Alzheimer's disease, but appears to insufficient by itself to cause clinical dementia.