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Reduced parahippocampal volume and psychosis symptoms in Alzheimer's disease

McLachlan, E; Bousfield, J; Howard, R; Reeves, S; (2018) Reduced parahippocampal volume and psychosis symptoms in Alzheimer's disease. International Journal of Geriatric Psychiatry , 33 (2) pp. 389-395. 10.1002/gps.4757. Green open access

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Abstract

OBJECTIVE: Establishing structural imaging correlates of psychosis symptoms in Alzheimer's disease (AD) could localise pathology and target symptomatic treatment. This study investigated whether psychosis symptoms are associated with visuoperceptual or frontal networks, and whether regional brain volume differences could be linked with the paranoid (persecutory delusions) or misidentification (misidentification phenomena and/or hallucinations) subtypes. METHODS: A total of 104 patients with probable AD (AddNeuroMed; 47 psychotic, 57 non-psychotic), followed up for at least one year with structural MRI at baseline. Presence and subtype of psychosis symptoms were established using the Neuropsychiatric Inventory. Volume and cortical thickness measures in visuoperceptual and frontal networks were explored using multivariate analyses to compare with both a global (psychotic versus not) and subtype-specific approach, adjusting for potential confounding factors. RESULTS: There was a significant main effect of psychosis subtypes on the ventral visual stream region of interest (F30,264  = 1.65, p = 0.021, np2  = 0.16). This was explained by reduced left parahippocampal gyrus volume (F1,97  = 11.1, p = 0.001, np2  = 0.10). When comparisons were made across psychosis subtypes, left parahippocampal volume reduction remained significant (F7,95  = 3.94, p = 0.011, np2  = 0.11) and was greatest for the misidentification and mixed subtypes compared to paranoid and non-psychotic groups. CONCLUSIONS: These findings implicate the ventral visual stream in psychosis in AD, consistent with integrative theories regarding origins of psychosis, and provide further evidence for a role in the misidentification subtype. Specifically, reduced volume in the parahippocampal gyrus is implicated in misidentification delusion formation, which we hypothesise is due to its role in context attribution.

Type: Article
Title: Reduced parahippocampal volume and psychosis symptoms in Alzheimer's disease
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/gps.4757
Publisher version: http://dx.doi.org/10.1002/gps.4757
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Alzheimer's disease; psychosis; subtypes; misidentification; parahippocampal gyrus
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/1567390
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