O1–04–08: Left orbitofrontal atrophy correlates with disinhibition and apathy in frontotemporal degeneration

or substantia nigra inclusions were observed. Cases of AD without LBP (AD alone) were selected from the same sample for comparison of clinical features. Results: Nineteen cases fulfilled criteria for AP-LBP. Eighteen of these (95%), had concomitant neuropathological AD. Neuropsychological testing at enrollment revealed no significant differences between AP-LBP and AD alone. However, the rate of decline for the Mini-Mental State Exam (MMSE) was significantly greater in AP-LBP versus AD alone (5.7 vs. 3.6 pts/yr, p 0.05). Examination of MMSE subscores found that this latter finding was due to a greater rate of decline in memory and language performance in AP-LBP cases. Clinically AP-LBP cases had a higher frequency of pacing than AD alone, but similar frequencies of hallucinations and parkinsonism. Conclusions: AP-LBP is observed primarily in cases with concomitant neuropathological AD, although not always in those cases with the most severe AD pathology. Despite limited distribution of LBP in AP-LBP, this change is associated with a more rapid decline of cognitive function, including language. This latter finding suggests AP-LBP may be associated with additional, more anatomically diffuse, neuropathological change.