Alzheimer's disease

Alzheimer's disease
Other names	Alzheimer's dementia
Diagram of a normal brain compared to the brain of a person with Alzheimer's
Pronunciation	/ˈæltshaɪmərz/, US also /ˈɑːlts-/
Specialty	Neurology
Symptoms	Memory loss, problems with language, disorientation, mood swings[1][2]
Complications	Infections, falls and aspiration pneumonia in the terminal stage[3]
Usual onset	Over 65 years old[4]
Duration	Long term[2]
Causes	Poorly understood[1]
Risk factors	Genetics, head injuries, clinical depression, hypertension,[1] psychological stress,[5] lack of physical[6] and mental[5][7] exercise
Diagnostic method	Based on symptoms and cognitive testing after ruling out other possible causes[8]
Differential diagnosis	Normal brain aging,[1] Lewy body dementia,[9] Trisomy 21[10]
Medication	Acetylcholinesterase inhibitors, NMDA receptor antagonists[11]
Prognosis	Life expectancy 3–9 years[12]
Frequency	50 million (2020)[13]
Named after	Alois 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][14] 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.^[15] 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.^[16][12]

The cause of Alzheimer's disease is poorly understood.^[15] 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 progress of the protein misfolding disease is largely associated with amyloid plaques, neurofibrillary tangles, and loss of neuronal 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.^[15] 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 ageing, 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.^[13] 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,^[15] 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.^[13] It is ranked as the seventh leading cause of death worldwide.^[30]