Alzheimer's disease

Alzheimer's disease (AD) is a <a href="/facts/Neurodegenerative_disease/HTDrVEqc">neurodegenerative disease</a> that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of <a href="/facts/Dementia/T0MRDE9I">dementia</a>. The most common early symptom is difficulty in <a href="/facts/Short-term_memory/xaFod2bp">remembering recent events</a>. As the disease advances, symptoms can include <a href="/facts/Aphasia/BWGvlEAC">problems with language</a>, <a href="/facts/Orientation_(mental)/LtTwMXqE">disorientation</a> (including easily getting lost), <a href="/facts/Mood_swing/NWYoAMyP">mood swings</a>, loss of <a href="/facts/Motivation/uqLMfLKq">motivation</a>, <a href="/facts/Self-neglect/papEoWfm">self-neglect</a>, and <a href="/facts/Challenging_behaviour/W082K9hD">behavioral issues</a>. As a person's condition declines, they often <a href="/facts/Solitude/UkSD84c6">withdraw from family and society</a>. 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.
The causes of Alzheimer's disease remain poorly understood. There are many environmental and genetic <a href="/facts/Risk_factor/N0YTUyer">risk factors</a> associated with its development. The strongest genetic risk factor is from an <a href="/facts/Allele/8FxCS9KA">allele</a> of <a href="/facts/Apolipoprotein_E/x3a7VME2">apolipoprotein E</a>. Other risk factors include a history of <a href="/facts/Head_injury/KvqnqIbG">head injury</a>, <a href="/facts/Clinical_depression/l2lQeWqr">clinical depression</a>, and <a href="/facts/High_blood_pressure/wlAvBfcf">high blood pressure</a>. The progression of the disease is largely characterised by the accumulation of <a href="/facts/Proteinopathy/woWrXMXM">malformed protein deposits</a> in the <a href="/facts/Cerebral_cortex/GpXosGHP">cerebral cortex</a>, called <a href="/facts/Amyloid_plaques/M3c8t7xI">amyloid plaques</a> and <a href="/facts/Neurofibrillary_tangles/WBxMueTr">neurofibrillary tangles</a>. These misfolded <a href="/facts/Protein_aggregation/94Ad1VqG">protein aggregates</a> interfere with normal cell function, and over time lead to irreversible <a href="/facts/Neurodegenerative_disease/HTDrVEqc">degeneration of neurons</a> and loss of <a href="/facts/Synapse/vdMRJCUn">synaptic connections</a> in the <a href="/facts/Human_brain/qfSwSB8K">brain</a>. A probable diagnosis is based on the history of the illness and <a href="/facts/Cognitive_test/07ruSL1L">cognitive testing</a>, with <a href="/facts/Medical_imaging/pL6JyJEp">medical imaging</a> and <a href="/facts/Blood_test/zevsf3rC">blood tests</a> to rule out other possible causes. Initial symptoms are often mistaken for <a href="/facts/Normal_brain_aging/7hFvvqf0">normal brain aging</a>. <a href="/facts/Histopathology/9Eggjrg4">Examination of brain tissue</a> is needed for a definite diagnosis, but this can only take place <a href="/facts/Postmortem_studies/kLeFTAzp">after death</a>.
No treatments can stop or reverse its progression, though some may temporarily improve symptoms. A <a href="/facts/Healthy_diet/sjJBXc4l">healthy diet</a>, <a href="/facts/Physical_activity/16Cmj4Kd">physical activity</a>, and <a href="/facts/Social_engagement/ansva0bk">social engagement</a> are generally beneficial in aging, and may help in reducing the risk of cognitive decline and Alzheimer's. Affected people become increasingly reliant on others for assistance, often placing a burden on <a href="/facts/Dementia_caregiving/gySl7Vjx">caregivers</a>. The pressures can include social, psychological, physical, and economic elements. Exercise programs may be beneficial with respect to <a href="/facts/Activities_of_daily_living/0AYDmmSA">activities of daily living</a> and can potentially improve outcomes. Behavioral problems or <a href="/facts/Psychosis/cVGd7MKK">psychosis</a> due to dementia are sometimes treated with <a href="/facts/Antipsychotic/7bNTg7T3">antipsychotics</a>, but this has an increased risk of early death. 
As of 2020, there were approximately 50 million people worldwide with Alzheimer's disease. It most often begins in people over 65 years of age, although up to 10% of cases are <a href="/facts/Early-onset_Alzheimer%27s_disease/o64ng9w2">early-onset</a> impacting those in their 30s to mid-60s. It affects about 6% of people 65 years and older, and women more often than men. The disease is named after German psychiatrist and pathologist <a href="/facts/Alois_Alzheimer/aEvPecpe">Alois Alzheimer</a>, who first described it in 1906. Alzheimer's financial burden on society is large, with an estimated global annual cost of US$1 trillion. It is ranked as the <a href="/facts/List_of_causes_of_death_by_rate/KuqKAzeB">seventh leading cause of death</a> worldwide. 
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 <a href="/facts/National_Institutes_of_Health/G3Eytfcc">National Institutes of Health</a> 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. In the <a href="/facts/European_Union/6GYcR8qM">European Union</a>, the 2020 <a href="/facts/Horizon_Europe/6ggFoxbN">Horizon Europe</a> research programme awarded over €570 million for dementia-related projects.

Alzheimer's disease open-in-new

Alzheimer's disease