- Alzheimer disease (AD) is a progressive, irreversible, degenerative neurologic disease that results in neuron death.
- AD represents 60–80% of dementia.
- AD is the sixth leading cause of death in the United States (1).
- People ≥65 years with new AD live 4 to 8 years on average.
- AD is underdiagnosed (~50%) and >50% with AD unaware of diagnosis
- Economic burden in 2018: ~$305 billion, projected $1.1 trillion by 2050 (1)
- Dementia should be distinguished from:
- Age-related cognitive decline: lifelong changes in mental ability and memory; part of normal aging
- Mild cognitive impairment (MCI): greater impairment than cognitive decline
- MCI: People are generally able to live independently from a cognitive perspective.
- MCI: affects 15–20% of those ≥65 years, with 32–38% developing dementia within 5 years
- AD diagnostic classification:
- Preclinical AD: no cognitive symptoms, AD biomarkers present
- MCI due to AD: often only memory symptoms
- Dementia due to AD:
- Early stage: memory impairment >MCI
- Middle stage: impairment in communication and response to environment
- Late stage: lose ability to appropriately recognize and respond to environment
- System(s) affected: nervous
- Synonym(s): presenile dementia; senile dementia of the Alzheimer type
- Predominant age: >65 years
- Incidence: females = males
- Prevalence: females > males
New cases of AD in the United States: 484,000/year (1)
- 65 to 75 years: 2 new cases per 1,000 people
- 75 to 84 years: 11 new cases per 1,000 people
- ≥85 years: 37 new cases per 1,000 people
~5.8 million in United States; ~44 million worldwide
- 13.8 million in United States by 2050
- 1 in 10 of those ≥65 years have AD dementia.
- 32% of those ≥85 years have AD dementia.
- ~200,000 in United States with early-onset AD (<65 years)
Etiology and Pathophysiology
- Progressive, irreversible disease where cognitive impairment worsens over time
- β-amyloid plaques outside of neurons and τ protein tangles inside of neurons, resulting in loss of connections and neuron death
- Age, genetics, systemic diseases, lifestyle behaviors may influence AD progression.
- Autosomal dominant: <5% of AD, usually early onset (<65 years)
- Familial inheritance AD (nonautosomal dominant): 15–25% of AD
- Nonmodifiable risk factors: (1),(2),(3)
- Age, gender (due to longer lifespan in women)
- Family history, genetic mutations
- APOE-e4 gene variant: e4 heterozygous 2- to 3-fold risk; e4 homozygous 8-fold risk
- Racial and ethnic differences in AD exist.
- Cardiovascular disease–related risk factors:
- Hypertension (HTN) (especially in midlife years); hyperlipidemia
- Obesity, diabetes, and impaired glucose processing
- Tobacco use, unhealthy diet, lack of physical activity
- Cerebrovascular (stroke) risks and injury
- Other potentially modifiable risk factors:
- Less years of formal education (<8th grade)
- Lack of continuous brain activity—learning
- Traumatic brain injuries: repetitive mild and moderate/severe
- Lack of social engagement
- Late-life depression
- Poor quality and inadequate sleep
- Hearing and vision deficits
- High alcohol consumption
- Possible environmental factors (e.g., pollution)
- Cognitive decline and impairment are top concerns of people ≥50 years.
- Treat psychiatric conditions and avert delirium during hospitalizations.
Commonly Associated Conditions
- Down syndrome
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Domino, Frank J., et al., editors. "Alzheimer Disease." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2020. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116014/all/Alzheimer_Disease.
Alzheimer Disease. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2020. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116014/all/Alzheimer_Disease. Accessed May 31, 2023.
Alzheimer Disease. (2020). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (27th ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116014/all/Alzheimer_Disease
Alzheimer Disease [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2020. [cited 2023 May 31]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116014/all/Alzheimer_Disease.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Alzheimer Disease ID - 116014 ED - Domino,Frank J, ED - Baldor,Robert A, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116014/all/Alzheimer_Disease PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -