Neurobiology of Delusions in Alzheimer’s Disease

  • Zahinoor Ismail
  • Minh-Quan Nguyen
  • Corinne E. Fischer
  • Tom A. Schweizer
  • Benoit H. Mulsant
  • David Mamo


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.


Alzheimer’s Dementia Psychosis Delusions Persecutory delusions Misidentifications BPSD Neuropsychiatry Neuropsychiatric symptoms NPS Neuropathology Genetics Cognition Paranoia Suspiciousness Confabulation 


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Zahinoor Ismail
    • 1
    • 5
  • Minh-Quan Nguyen
    • 1
  • Corinne E. Fischer
    • 2
    • 3
  • Tom A. Schweizer
    • 4
  • Benoit H. Mulsant
    • 1
    • 2
  • David Mamo
    • 1
    • 2
  1. 1.Centre for Addiction and Mental HealthGeriatric Mental Health Program, University of TorontoTorontoCanada
  2. 2.Department of PsychiatryUniversity of TorontoTorontoCanada
  3. 3.Mental Health Service/Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael’s HospitalUniversity of TorontoTorontoCanada
  4. 4.Keenan Research Centre of the Li Ka Shing Knowledge Institute and the Division of Neurosurgery, St. Michael’s HospitalUniversity of TorontoTorontoCanada
  5. 5.Department of PsychiatryUniversity of CalgaryCalgaryCanada

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