title: Neurobiology of delusions in Alzheimer's disease.
abstract: Alzheimer's disease (AD) is associated with cognitive and functional impairment as well as neuropsychiatric sequelae, including psychotic symptoms such as delusions and hallucinations. Strong evidence supports the need to study delusions separate from hallucinations. Integrating the epidemiology, clinical correlates, and neuropathological and genetic literature for delusions in AD allows us to speculate on etiology and mechanisms. Plaque and tangle deposition in individuals with susceptible alleles of serotonergic, muscarinic, nicotinic, or Apoε4 genes appears to result in disruption of cortical circuitry, culminating in delusions. While delusions in AD correspond to a phenotype distinct from AD without delusions, subtypes of delusions may also define further distinct clinical entities. Persecutory delusions may occur earlier in the illness and have a more significant genetic component than misidentification delusions, which are associated with increased cognitive impairment and advanced dementia. Clearly distinguishing between these two syndromes is essential to making progress in the area of delusions in AD.
authors.affiliation: Centre for Addiction and Mental Health, Geriatric Mental Health Program, University of Toronto, 1001 Queen Street W., Toronto, Ontario, Canada. zahinoor@gmail.com
authors.forename: Zahinoor
authors.initials: Z
authors.lastname: Ismail
authors.forename: Minh-Quan
authors.initials: MQ
authors.lastname: Nguyen
authors.forename: Corinne E
authors.initials: CE
authors.lastname: Fischer
authors.forename: Tom A
authors.initials: TA
authors.lastname: Schweizer
authors.forename: Benoit H
authors.initials: BH
authors.lastname: Mulsant
authors.forename: David
authors.initials: D
authors.lastname: Mamo
mesh_terms: D000544:Alzheimer Disease / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D001921:Brain / Q000503:physiopathology*; D003072:Cognition Disorders / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D003702:Delusions / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D006801:Humans