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Cognitive phenotype of psychotic symptoms in Alzheimer's disease: evidence for impaired visuoperceptual function in the misidentification subtype

Reeves, SJ; Clark-Papasavas, C; Gould, RL; Ffytche, D; Howard, RJ; (2015) Cognitive phenotype of psychotic symptoms in Alzheimer's disease: evidence for impaired visuoperceptual function in the misidentification subtype. International Journal of Geriatric Psychiatry , 30 (12) pp. 1147-1155. 10.1002/gps.4265. Green open access

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Abstract

Background: Establishing the cognitive phenotype of psychotic symptoms in Alzheimer’s disease (AD) could localise discrete pathology and target symptomatic treatment. This study aimed to establish whether psychotic symptoms would be associated with poorer performance on neuropsychological tests known to correlate with striatal dopaminergic function and to investigate whether these differences would be attributed to the paranoid (persecutory delusions) or misidentification (misidentification phenomena +/�hallucinations) subtype. Methods: Seventy patients with probable AD (34 psychotic and 36 nonpsychotic) were recruited to the study. Analysis of covariance was used to compare motor speed and the rapid visual processing test of sustained visual attention, after adjusting for potential confounding factors. Multivariate analyses were used to compare performance across other cognitive domains. Significant findings were explored by separating patients on the basis of subtype. Results: Rapid visual processing performance accuracy was reduced in patients with psychotic symptoms (F1,58= 5.94, p= 0.02) and differed significantly across subtypes (F2,51= 3.94, p= 0.03), largely because of poorer performance in the misidentification compared with nonpsychotic group. Multivariate analyses (corrected for multiple comparisons) showed poorer performance on the incomplete letters task in psychotic patients (F1,63= 8.77, p= 0.004) and across subtypes (F2,55= 10.90, p<0.001), similarly attributed to the misidentification subtype. Conclusions: These findings provide further support of the involvement of dopaminergic networks in the psychosis endophenotype in AD and, in addition, implicate the ventral (temporo-occipital) pathway in the misidentification subtype. Future studies should investigate the early trajectory of neuropathological change in vivo across psychosis subtypes.# 2015 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons, Ltd.

Type: Article
Title: Cognitive phenotype of psychotic symptoms in Alzheimer's disease: evidence for impaired visuoperceptual function in the misidentification subtype
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/gps.4265
Publisher version: http://doi.org/10.1002/gps.4265
Language: English
Additional information: Copyright © 2015 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: Alzheimer’s disease; psychosis; subtypes; RVP; misidentification; ventral visual pathway
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Division of Psychiatry
URI: https://discovery.ucl.ac.uk/id/eprint/1490236
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