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Alzheimer disease

Last reviewed: 24 Jul 2025
Last updated: 20 Aug 2025

Summary

Definition

History and exam

Key diagnostic factors

  • memory loss
  • disorientation
  • nominal dysphasia
  • misplacing items/getting lost
  • apathy
  • decline in activities of daily living and instrumental activities of daily living (IADLs)
  • personality change
  • unremarkable initial physical exam
Full details

Other diagnostic factors

  • mood and behavior changes
  • poor abstract thinking
  • constructional dyspraxia
  • prosopagnosia
  • autoprosopagnosia
Full details

Risk factors

  • advanced age
  • family history
  • genetics
  • Down syndrome
  • cerebrovascular disease
  • lifestyle factors and environment
  • use of certain drugs
  • less than high school education
  • traumatic brain injury
  • depression
  • hearing loss
  • periodontal disease
  • visual impairment
  • herpes simplex virus type 1 (HSV-1) infection
  • hyperlipidemia
  • female sex
  • elevated plasma homocysteine level
  • surgery under general anesthesia
Full details

Diagnostic tests

1st tests to order

  • cognitive testing
  • CBC
  • metabolic panel
  • serum thyroid-stimulating hormone (TSH)
  • serum vitamin B12
  • urine drug screen
  • CT brain (without contrast)
  • MRI brain (without contrast)
Full details

Tests to consider

  • cerebrospinal fluid (CSF) analysis
  • serum rapid plasma reagin/Venereal Disease Research Laboratory (VDRL)
  • serum HIV testing
  • formal neuropsychological testing
  • genetic testing
  • fluorodeoxyglucose-PET (FDG-PET)
  • CSF biomarker testing
Full details

Emerging tests

  • amyloid-PET
  • blood biomarkers

Treatment algorithm

ONGOING

all patients

Contributors

Authors

Judith Neugroschl, MD

Associate Professor of Psychiatry

Alzheimer's Disease Research Center

Icahn School of Medicine at Mount Sinai

New York

NY

Disclosures

JN participates in research funded by National Institutes for Health (NIH) grants. The Alzheimer's Disease Research Center is a site for clinical research but JN is not the site Principal Investigator, has no role in purchasing nor choosing the studies, and gains no compensation if it succeeds. JN helps to edit the Focus on Healthy Aging Alzheimer's yearly report.

Acknowledgements

Dr Judith Neugroschl would like to gratefully acknowledge Dr Brandy R. Matthews, Dr Asif S. Bhutto, and Dr Julie K. Gammack, the previous contributors to this topic.

Disclosures

BRM, ASB, and JKG declare that they have no competing interests.

Peer reviewers

Roy J. Goldberg, MD, FACP, AGSF, CMD

Medical Director

Kings Harbor Multicare Center

New York

NY

Disclosures

RJG declares that he has no competing interests.

Philip Scheltens, MD, PhD

Professor of Neurology

Department of Neurology/Alzheimer Center

VU University Medical Center

Amsterdam

The Netherlands

Disclosures

PS declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Livingston G, Huntley J, Liu KY, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing commission. Lancet. 2024 Aug 10;404(10452):572-628. Abstract

American College of Radiology. ACR appropriateness criteria: dementia. 2024 [internet publication].Full text

McShane R, Westby MJ, Roberts E, et al. Memantine for dementia. Cochrane Database Syst Rev. 2019 Mar 20;(3):CD003154.Full text  Abstract

Birks JS, Chong LY, Grimley Evans J. Rivastigmine for Alzheimer's disease. Cochrane Database Syst Rev. 2015 Sep 22;(9):CD001191.Full text  Abstract

Birks JS, Harvey RJ. Donepezil for dementia due to Alzheimer's disease. Cochrane Database Syst Rev. 2018 Jun 18;(6):CD001190.Full text  Abstract

Reus VI, Fochtmann LJ, Eyler AE, et al. The American Psychiatric Association practice guideline on the use of antipsychotics to treat agitation or psychosis in patients with dementia. Am J Psychiatry. 2016 May 1;173(5):543-6.Full text  Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
  • Differentials

    • Delirium
    • Depression
    • Vascular dementia
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  • Guidelines

    • ACR appropriateness criteria: dementia
    • European intersocietal recommendations for the biomarker-based diagnosis of neurocognitive disorders
    More Guidelines
  • Patient information

    Alzheimer disease and other kinds of dementia

    Caring for someone with dementia

    More Patient information
  • Calculators

    Geriatric Depression Scale

    More Calculators
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