NEUROPATHOLOGICAL CORRELATES OF PSYCHOTIC PHENOMENA IN CONFIRMED ALZHEIMERS-DISEASE

Background. The prevalence of psychotic phenomena in confirmed Alzheim er's disease (AD) and their potential neuropathological correlates hav e rarely been the subject of prospective investigation. Method. Psycho pathological disturbances were recorded prospectively according to the Geriatric Mental State Schedule and the CAMDEX. The frequency of thes e phenomena and neuropathological changes were examined in 56 patients with definite AD. Results. Hallucinations had been documented in 13 p atients, paranoid delusions in 9 and delusional misidentification (e.g . the Capgras-type and the 'phantom boarder' symptoms) in 14 patients. Misidentifications were associated with lower neurone counts in the a rea CA1 of the hippocampus. Delusions and hallucinations were observed in patients with less severe cell loss in the parahippocampal gyrus a nd with lower cell counts in the dorsal raphe nucleus. A decrease of n eurones in the locus coeruleus in a subset of depressed patients with AD had been reported earlier. Delusions and delusional misidentificati on were common in 5 patients with basal ganglia mineralisation, but th ere was no statistically significant association of these symptoms wit h the presence of Lewy bodies in the brainstem and neocortex of our pa tient sample. Conclusions. These findings are compatible with the view that morphological changes in certain brain areas may promote the dev elopment of psychotic phenomena in AD. AD may offer a model for the un derstanding of pathomechanisms underlying the development of psychopat hological disturbances in other psychoses with more discrete neuropath ological changes.