Alzheimer's disease | |
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Other names | Alzheimer's dementia |
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Diagram of a normal brain compared to the brain of a person with Alzheimer's | |
Pronunciation |
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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 3–12 years[11][12][13] |
Frequency | 50 million (2020)[14] |
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][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 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.[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] or slow the progression of the disease.[23] 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.[24] The pressures can include social, psychological, physical, and economic elements.[24] Exercise programs may be beneficial with respect to activities of daily living and can potentially improve outcomes.[25] Behavioral problems or psychosis due to dementia are sometimes treated with antipsychotics, but this has an increased risk of early death.[26][27]
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.[28][4] It affects about 6% of people 65 years and older,[16] and women more often than men.[29] The disease is named after German psychiatrist and pathologist Alois Alzheimer, who first described it in 1906.[30] 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.[31]
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