470. No increased severity of neuropathologic features in Alzheimer’s disease with psychosis

Abstract

Psychotic symptoms in Alzheimer’s Disease (AD with psychosis, AD+P) have been associated with increased cognitive impairment and more rapid functional decline. Prior studies have conflicted regarding whether AD+P subjects have more severe neuropathologic findings at post-mortem exam. We examined middle frontal cortex, hippocampus, inferior parietal cortex, superior temporal cortex, occipital cortex, and transentorhinal cortex in 24 AD+P subjects and 25 AD subjects without psychosis. Subjects were matched for age, gender, race, and the presence of Lewy bodies. The severity of neuritic plaques (NP) and neurofibrillary tangles (NFT) were scored as per CERAD protocols. Statistical analyses were corrected for multiple comparisons. We found auditory hallucinations to be associated with reduced severity of NP in the transentorhinal cortex. There were no associations of NP severity with other psychotic symptoms. There was no association between severity of NFT and any psychotic symptom. To exclude the possibility that we failed to detect increased pathology in AD+P due to a “ceiling effect” of the CERAD severity ratings, we rescored NP severity using a scale with higher range in a subset of 19 subjects (9 AD+P). AD+P was not significantly associated with NP severity using these revised criteria. Results from rescoring of NFT severity have yet to be completed. The more rapidly deteriorating course in AD+P does not appear to result from increased severity of NP and NFT formation. This may reflect the modest correlation of NPs and NFTs with cognitive impairment. Future studies of AD+P should examine markers of neuronal and/or synaptic integrity.