Dementia in older adults is caused by a variety of diseases and conditions that damage brain cells or the connections between them, with Alzheimer’s disease being the single most common cause and vascular problems a leading second cause[4][1].
What happens in the brain
– Alzheimer’s disease causes progressive loss of brain cells and connections through abnormal protein deposits called amyloid plaques and tau tangles, which interfere with neuron function and lead to gradual memory loss and cognitive decline[4].
– Vascular dementia happens when reduced blood flow or small strokes damage brain tissue; repeated small infarcts or chronic small-vessel disease produce stepwise or patchy decline in thinking skills[1][2].
– Other pathologies that directly harm brain cells can cause dementia, including Lewy bodies (abnormal protein clumps seen in dementia with Lewy bodies), frontotemporal degeneration (which mainly affects the frontal and temporal lobes and changes behavior and language), and diseases such as Huntington disease or Parkinson disease with dementia[1][4].
Medical and treatable causes
– Some metabolic, infectious, or structural brain problems can produce dementia-like symptoms and are potentially treatable, for example severe thyroid disease, certain vitamin deficiencies (notably thiamine in alcohol-related brain damage), neurosyphilis, and some brain tumors or encephalitis[1][3].
– Long-term heavy alcohol use causes alcohol-related brain damage by direct nerve-cell injury, loss of vitamins, and increased risk of strokes, increasing dementia risk both directly and by promoting other dementias[3].
Risk factors that raise the chance dementia will develop
– Age is the strongest risk factor: risk increases substantially after age 65, though dementia is not an inevitable part of normal aging[6][1].
– Vascular risk factors such as high blood pressure, diabetes, smoking, high cholesterol, and obesity raise the risk of vascular dementia and also of Alzheimer’s disease by harming brain blood supply and health[1][2].
– Genetics and family history matter: certain gene variants (for example APOE) increase Alzheimer’s risk, and family history raises risk for some dementias[1].
– Lifestyle and social factors — low physical activity, poor diet, smoking, excessive alcohol use, and limited social and cognitive engagement — are associated with higher dementia risk and are targets for prevention guidance from health organizations[1].
– Other health conditions including depression, traumatic brain injury, and some sleep disorders can increase risk or unmask underlying disease[1][5][7].
How these causes lead to the symptoms people notice
– Different brain diseases affect different networks, so the first problems vary: Alzheimer’s typically begins with episodic memory loss, vascular dementia may cause slowed thinking and executive dysfunction, Lewy body disease can cause visual hallucinations and fluctuating attention, and frontotemporal dementia often first changes personality and language[4][5].
– Because many causes can overlap in older adults, mixed dementia (for example Alzheimer’s pathology plus vascular damage) is common and can worsen symptoms and progression[1].
Prevention and treatability
– Some contributors to dementia are potentially modifiable: controlling blood pressure, treating diabetes, stopping smoking, reducing harmful alcohol use, staying physically active, and keeping mentally and socially engaged can lower risk or delay onset[1][3].
– While most neurodegenerative causes (for example Alzheimer’s, Lewy body, frontotemporal) currently have no cure, identifying and treating reversible contributors (vitamin deficiencies, medication effects, treatable infections, or metabolic problems) can improve or stabilize symptoms in some people[1][6].
Sources
https://www.britannica.com/science/dementia
https://www.rezilirhealth.com/alzheimers-care-doctor-hollywood-florida/
https://www.alzheimers.org.uk/about-dementia/types-dementia/alcohol-related-dementia
https://blog.bonsecours.com/healthy/alzheimers-dementia-early-warning-signs/
https://www.alzheimersresearchuk.org/news/spotting-early-signs-that-could-be-dementia-when-should-you-worry/
https://www.agingresearch.org/advocacy/alzheimers-disease-and-related-dementias/
https://www.nationalacademies.org/read/25064/chapter/15
