P1‐018: HIPPOCAMPAL GREY MATTER ATROPHY IS ASSOCIATED WITH THE FREE AND CUED SELECTIVE REMINDING TEST

and neurodegenerative pathologies, including TAR-DNA-binding protein43 (TDP-43). Anti-phospho-TDP-43 (pTDP-43) is suggested to be a marker for granulovacuolar degeneration (GVD).Methods:H ippocampal sections (9mm thick) from 235 brains donated for the population-based clinicopathological Cambridge City over 75 Cohort Study (CC75C) were stained with haematoxylin-eosin (HE) and antiphosho-TDP-43. HScl was defined as no more than one identifiable pyramidal neuron in each CA1 field of view at 200-fold magnification of a HE-section, not explained by an infarct, and no obvious neuron loss in other hippocampal areas. GVD was assessed on both HEand pTDP-43-stained sections. TDP-43 and GVD pathology severity was scored in various hippocampal areas and the entorhinal and temporal cortex by layer as none, one, mild, moderate or severe. Measures for Alzheimer’s disease (AD)-type and vascular pathologies were based on the Consortium to Establish a Registry of AD (CERAD) protocol. Clinical data was obtained from CC75C surveys. Results: Eleven HScl cases (4.7%) were identified, accounting for 6.7% of those with dementia and 10.8% of those aged 95 years or more. All evaluated HScl cases showed TDP-43-positive inclusions in the dentate gyrus (p<0.001 compared to non-HScl cases). Clinically, most HScl cases were diagnosed as having Alzheimer’s dementia. However, HScl was not associated with any CERAD parameter for AD or cerebrovascular pathology. Severity of TDP-43 pathology was similar in HScl cases with Braak stage V-VI (n1⁄44) and those without (n1⁄45). HScl did not associate with GVD. GVD was not reliably stained by anti-pTDP-43.Similar results were obtained from a second population-based study. Conclusions: Our results indicate that in the general elderly population HScl is strongly associated with hippocampal TDP-43 pathology and independent from AD and vascular disease.