title: Β-Amyloid Burden is Not Associated with Cognitive Impairment in Schizophrenia: A Systematic Review.
abstract: Current literature suggests that the pathology of schizophrenia (SCZ) has developmental origins. However, the neurodevelopmental theory of SCZ cannot solely explain progressive neurodegenerative processes in the illness. There is evidence of accelerated cognitive decline and increased risk of dementia in elderly patients with SCZ. Investigating β-amyloid (Aβ), we conducted a systematic review focusing on Aβ in patients with SCZ. An OVID literature search using PsychINFO, Medline, and Embase databases was conducted, looking for studies that compared Aβ levels between patients with SCZ and either elderly control subjects, patients with Alzheimer disease (AD), or patients with other psychiatric illnesses. Among 14 identified studies, 11 compared Aβ between SCZ and elderly control subjects, 7 between SCZ and AD, and 3 between SCZ and other psychiatric illnesses. As a result, no evidence was found suggesting that Aβ levels differ in patients with SCZ from elderly control subjects or patients with other psychiatric illnesses. All seven studies reported lower cortical Aβ in patients with SCZ than patients with AD. Furthermore, three of the four studies, which investigated the relationship between Aβ and cognitive impairment in SCZ, observed no association between two factors. The limitations of the included studies are small sample sizes, the inclusion of cerebrospinal fluid Aβ or postmortem plaques rather than cortical Aβ assessment in vivo, and the investigation of different brain regions. In conclusion, Aβ deposition is not associated with cognitive decline in late-life SCZ. Future studies should investigate other neurodegenerative indicators in SCZ to better understand the pathophysiologic mechanisms underlying this illness.
authors.affiliation: Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Jun Ku
authors.initials: JK
authors.lastname: Chung
authors.affiliation: Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Nakajima
authors.affiliation: Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Plitman
authors.affiliation: Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Iwata
authors.affiliation: Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Danielle
authors.initials: D
authors.lastname: Uy
authors.affiliation: Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Philip
authors.initials: P
authors.lastname: Gerretsen
authors.affiliation: Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Fernando
authors.initials: F
authors.lastname: Caravaggio
authors.affiliation: Cerebral Imaging Centre, Douglas Mental Health Institute, McGill University, Montreal, Quebec, Canada; Department of Psychiatry and Biomedical Engineering, McGill University, Montreal, Quebec, Canada.
authors.forename: M Mallar
authors.initials: MM
authors.lastname: Chakravarty
authors.affiliation: Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Multimodal Imaging Group-Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Geriatric Mental Health Division, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan. Electronic address: ariel_graff@yahoo.com.mx.
authors.forename: Ariel
authors.initials: A
authors.lastname: Graff-Guerrero
mesh_terms: D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D001921:Brain / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000134:cerebrospinal fluid / Q000473:pathology / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D058225:Plaque, Amyloid / Q000473:pathology*; D012559:Schizophrenia / Q000134:cerebrospinal fluid / Q000473:pathology / Q000503:physiopathology*; D012565:Schizophrenic Psychology
chemical_list: D016229:Amyloid beta-Peptides
keywords: Alzheimer disease; cognitive decline; neurodegeneration; schizophrenia; β-Amyloid