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Alzheimer's disease

"Alzheimer" redirects here. For the eponym, see Alois Alzheimer. For other uses, see Alzheimer (disambiguation).

Alzheimer's disease
Other namesAlzheimer's dementia
Diagram of a normal brain compared to the brain of a person with Alzheimer's
Pronunciation
  • /ˈæltshaɪmərz/, US also /ˈɑːlts-/
SpecialtyNeurology
SymptomsMemory loss, problems with language, disorientation, mood swings[1][2]
ComplicationsInfections, falls and aspiration pneumonia in the terminal stage[3]
Usual onsetOver 65 years old[4]
DurationLong term[2]
CausesPoorly understood[1]
Risk factorsGenetics, head injuries, clinical depression, hypertension,[1] psychological stress,[5] lack of physical[6] and mental[5][7] exercise
Diagnostic methodBased on symptoms and cognitive testing after ruling out other possible causes[8]
Differential diagnosisNormal brain aging,[1] Lewy body dementia,[9] Trisomy 21[10]
MedicationAcetylcholinesterase inhibitors, NMDA receptor antagonists[11]
PrognosisLife expectancy 3–12 years[11][12][13]
Frequency50 million (2020)[14]
Named afterAlois Alzheimer

Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens,[2] and is the cause of 60–70% of cases of dementia.[2][15] The most common early symptom is difficulty in remembering recent events.[1] As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, self-neglect, and behavioral issues.[2] As a person's condition declines, they often withdraw from family and society.[16] Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to twelve years.[11][12][13]

The cause of Alzheimer's disease is poorly understood.[16] There are many environmental and genetic risk factors associated with its development. The strongest genetic risk factor is from an allele of apolipoprotein E.[17][18] Other risk factors include a history of head injury, clinical depression, and high blood pressure.[1] The progression of the disease is largely characterized by the accumulation of malformed protein deposits in the cerebral cortex, called amyloid plaques and neurofibrillary tangles. These misfolded protein aggregates interfere with normal cell function, and over time lead to irreversible degeneration of neurons and loss of synaptic connections in the brain.[19] A probable diagnosis is based on the history of the illness and cognitive testing, with medical imaging and blood tests to rule out other possible causes.[8][20] Initial symptoms are often mistaken for normal brain aging.[16] Examination of brain tissue is needed for a definite diagnosis, but this can only take place after death.[21][22]

No treatments can stop or reverse its progression, though some may temporarily improve symptoms.[2] A healthy diet, physical activity, and social engagement are generally beneficial in aging, and may help in reducing the risk of cognitive decline and Alzheimer's.[19] Affected people become increasingly reliant on others for assistance, often placing a burden on caregivers.[23] The pressures can include social, psychological, physical, and economic elements.[23] Exercise programs may be beneficial with respect to activities of daily living and can potentially improve outcomes.[24] Behavioral problems or psychosis due to dementia are sometimes treated with antipsychotics, but this has an increased risk of early death.[25][26]

As of 2020, there were approximately 50 million people worldwide with Alzheimer's disease.[14] It most often begins in people over 65 years of age, although up to 10% of cases are early-onset impacting those in their 30s to mid-60s.[27][4] It affects about 6% of people 65 years and older,[16] and women more often than men.[28] The disease is named after German psychiatrist and pathologist Alois Alzheimer, who first described it in 1906.[29] Alzheimer's financial burden on society is large, with an estimated global annual cost of US$1 trillion.[14] It is ranked as the seventh leading cause of death worldwide.[30]

Given the widespread impacts of Alzheimer's disease, both basic-science and health funders in many countries support Alzheimer's research at large scales. For example, the US National Institutes of Health program for Alzheimer's research, the National Plan to Address Alzheimer’s Disease, has a budget of US$3.98 billion for fiscal year 2026.[31] In the European Union, the 2020 Horizon Europe research programme awarded over €570 million for dementia-related projects.[32]

  1. ^ a b c d e f Cite error: The named reference Knopman2021 was invoked but never defined (see the help page).
  2. ^ a b c d e f "Dementia Fact sheet". World Health Organization. 15 March 2023. Retrieved 10 July 2023.
  3. ^ "Ask the Doctors - What is the cause of death in Alzheimer's disease?". www.uclahealth.org. Retrieved 18 March 2024.
  4. ^ a b Mendez MF (November 2012). "Early-onset Alzheimer's disease: nonamnestic subtypes and type 2 AD". Archives of Medical Research. 43 (8): 677–685. doi:10.1016/j.arcmed.2012.11.009. PMC 3532551. PMID 23178565.
  5. ^ a b Cite error: The named reference Yu 1201–1209 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Cheng2016 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Vina2018 was invoked but never defined (see the help page).
  8. ^ a b "Dementia diagnosis and assessment" (PDF). National Institute for Health and Care Excellence (NICE). Archived from the original (PDF) on 5 December 2014. Retrieved 30 November 2014.
  9. ^ Gomperts SN (April 2016). "Lewy Body Dementias: Dementia With Lewy Bodies and Parkinson Disease Dementia". Continuum (Review). 22 (2 Dementia): 435–463. doi:10.1212/CON.0000000000000309. ISSN 1080-2371. PMC 5390937. PMID 27042903.
  10. ^ Lott IT, Head E (March 2019). "Dementia in Down syndrome: unique insights for Alzheimer disease research". Nat Rev Neurol. 15 (3): 135–147. doi:10.1038/s41582-018-0132-6. PMC 8061428. PMID 30733618.
  11. ^ a b c "How Alzheimer's drugs help manage symptoms". Mayo Clinic. 30 August 2023. Retrieved 19 March 2024.
  12. ^ a b Schaffert J, LoBue C, Hynan LS, Hart J, Rossetti H, Carlew AR, et al. (2022). "Predictors of Life Expectancy in Autopsy-Confirmed Alzheimer's Disease". Journal of Alzheimer's Disease. 86 (1): 271–281. doi:10.3233/JAD-215200. PMC 8966055. PMID 35034898.
  13. ^ a b Todd S, Barr S, Roberts M, Passmore AP (November 2013). "Survival in dementia and predictors of mortality: a review". International Journal of Geriatric Psychiatry. 28 (11): 1109–1124. doi:10.1002/gps.3946. PMID 23526458.
  14. ^ a b c Cite error: The named reference Breijyeh2020 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Simon2018p111 was invoked but never defined (see the help page).
  16. ^ a b c d Burns A, Iliffe S (February 2009). "Alzheimer's disease". BMJ. 338: b158. doi:10.1136/bmj.b158. PMID 19196745. S2CID 8570146.
  17. ^ Cite error: The named reference Long was invoked but never defined (see the help page).
  18. ^ "Study reveals how APOE4 gene may increase risk for dementia". National Institute on Aging. 16 March 2021. Archived from the original on 17 March 2021. Retrieved 17 March 2021.
  19. ^ a b "Alzheimer's Disease Fact Sheet". National Institute on Aging. Archived from the original on 23 March 2022. Retrieved 23 March 2022.
  20. ^ Dementia: assessment, management and support for people living with dementia and their carers (Report). National Institute for Health and Care Excellence (NICE). 20 June 2018. NG97. Retrieved 8 July 2023.
  21. ^ Cite error: The named reference Khan2020 was invoked but never defined (see the help page).
  22. ^ Cite error: The named reference Gauthreaux2020 was invoked but never defined (see the help page).
  23. ^ a b Thompson CA, Spilsbury K, Hall J, Birks Y, Barnes C, Adamson J (July 2007). "Systematic review of information and support interventions for caregivers of people with dementia". BMC Geriatrics. 7: 18. doi:10.1186/1471-2318-7-18. PMC 1951962. PMID 17662119.
  24. ^ Forbes D, Forbes SC, Blake CM, Thiessen EJ, Forbes S (April 2015). "Exercise programs for people with dementia". The Cochrane Database of Systematic Reviews (Submitted manuscript). 132 (4): CD006489. doi:10.1002/14651858.CD006489.pub4. PMC 9426996. PMID 25874613.
  25. ^ "Low-dose antipsychotics in people with dementia". National Institute for Health and Care Excellence (NICE). Archived from the original on 5 December 2014. Retrieved 29 November 2014.
  26. ^ "Information for Healthcare Professionals: Conventional Antipsychotics". US Food and Drug Administration. 16 June 2008. Archived from the original on 29 November 2014. Retrieved 29 November 2014.
  27. ^ "Alzheimer's Disease Fact Sheet". National Institute on Aging. Archived from the original on 24 January 2021. Retrieved 25 January 2021.
  28. ^ Zhu D, Montagne A, Zhao Z (June 2021). "Alzheimer's pathogenic mechanisms and underlying sex difference". Cell Mol Life Sci. 78 (11): 4907–4920. doi:10.1007/s00018-021-03830-w. PMC 8720296. PMID 33844047.
  29. ^ Cite error: The named reference pmid9661992 was invoked but never defined (see the help page).
  30. ^ "The top 10 causes of death". www.who.int. Retrieved 19 March 2024.
  31. ^ Bertagnolli MM (5 August 2024). "Fiscal Year 2026 NIH Professional Judgment Budget for Alzheimer's Disease and Related Dementias Research: Advancing Progress in Dementia Research". US National Institutes of Health. Retrieved 23 September 2024.
  32. ^ "Alzheimer Europe: Horizon Europe research programme".

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