Dementia
Dementia is a syndrome involving decline in memory, thinking, behavior, communication, or daily function severe enough to interfere with everyday life. It has many causes, including Alzheimer disease, vascular brain injury, Lewy body disease, frontotemporal degeneration, and other brain conditions.
What dementia is
Dementia is not one disease. It is a syndrome: a pattern of symptoms involving decline in memory, thinking, language, judgment, behavior, or daily abilities. The decline is more serious than normal forgetfulness and interferes with everyday life, such as managing medicines, finances, cooking, driving, work, or personal care.
Dementia and Alzheimer disease
Alzheimer disease is the most common cause of dementia in older adults, but dementia can have many causes. Vascular dementia, Lewy body dementia, frontotemporal dementia, Parkinson disease dementia, traumatic brain injury, infections, alcohol-related brain damage, and mixed causes can all produce dementia symptoms. Saying dementia is not the same as saying Alzheimer disease.
Symptoms
Symptoms vary by cause and stage. They may include memory loss, getting lost, word-finding problems, poor judgment, difficulty planning, personality changes, hallucinations, movement changes, sleep problems, apathy, depression, anxiety, agitation, trouble recognizing people, or difficulty completing familiar tasks. Some forms affect behavior or language before memory.
Normal aging or warning sign
Normal aging can include slower recall or occasional forgetfulness. Dementia is different because the changes are persistent, progressive, and disruptive. Forgetting a word is common; losing the ability to follow a familiar recipe, pay bills, manage appointments, or find the way home may signal a need for evaluation.
Causes and types
Different dementias damage the brain in different ways. Alzheimer disease involves amyloid, tau, synapse loss, and brain network damage. Vascular dementia is linked to reduced blood flow or strokes. Lewy body dementia involves abnormal alpha-synuclein deposits and often brings visual hallucinations or movement symptoms. Frontotemporal dementia often affects behavior, personality, or language earlier.
Diagnosis
Diagnosis usually combines medical history, input from someone who knows the person well, cognitive testing, physical and neurological exam, medication review, mood assessment, and tests for treatable contributors. Brain imaging, blood tests, sleep evaluation, or specialist memory clinic assessment may be used. A careful diagnosis can guide care even when no cure exists.
Treatable contributors
Some conditions can worsen thinking or mimic dementia. Examples include medication side effects, depression, sleep apnea, thyroid disease, vitamin deficiencies, infections, dehydration, hearing or vision problems, substance use, and delirium. Finding and treating these contributors may improve function or prevent avoidable decline, even when a neurodegenerative disease is also present.
Treatment and support
Treatment depends on the cause and symptoms. Some medicines may help symptoms in certain dementias, and disease-targeting treatments may be considered for selected Alzheimer disease cases. Supportive care is central: routines, exercise, sleep care, hearing and vision support, home safety, caregiver education, social connection, managing other illnesses, and planning for future decisions.
Caregiving and safety
Dementia affects families, friends, and care partners. Practical issues may include cooking safety, wandering risk, driving, finances, medication management, falls, scams, nutrition, hygiene, communication, agitation, sleep disruption, and caregiver burnout. Early planning can preserve autonomy longer and reduce crisis decisions later.
Why it matters
Dementia matters because it changes memory, identity, independence, relationships, and community life. It is common with aging but is not an inevitable part of aging. Understanding dementia helps people seek evaluation earlier, recognize different causes, plan care, support caregivers, and reduce stigma around cognitive decline.