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What is dementia?

Dementia is an umbrella term for a decline in memory, thinking, or behavior serious enough to interfere with daily life. It is not a normal part of aging.

Updated 2026-02-15

It's a syndrome, not a disease

"Dementia" describes a set of symptoms — losing track of words, getting lost in familiar places, missing appointments, struggling with money. Several different diseases can cause those symptoms, and the cause matters because each one progresses differently and may respond to different medications.

The most common causes

  • Alzheimer's disease — about 60–70% of cases. Memory loss is usually the earliest sign.
  • Vascular dementia — caused by small strokes. Often stair-step progression.
  • Lewy body dementia — visual hallucinations, sleep disturbance, and Parkinson-like stiffness early on.
  • Frontotemporal dementia — personality, judgement, or language changes before memory.
  • Mixed dementia — most older brains show more than one cause.

What dementia is NOT

  • Normal aging. Forgetting names is common; forgetting how to use a fork is not.
  • Depression — but depression in older adults can look like dementia and is treatable.
  • Medication side effects — anticholinergics, benzodiazepines, opioids can all mimic dementia.
  • Thyroid, B12, or urinary tract infection — any of these can cause confusion overnight.

The first 30 days after a diagnosis

  1. Confirm the type — ask the doctor which form of dementia they suspect, and on what evidence.
  2. Power of attorney while your loved one can still sign. Don't wait.
  3. Update advance directives — healthcare proxy, living will, POLST.
  4. Audit medications with a pharmacist — many older adults take meds that worsen confusion.
  5. Check eligibility for the Medicare GUIDE program — a navigator, 24/7 helpline, and up to $2,500/year of respite at no cost.

Frequently asked questions

Is forgetting names a sign of dementia?
Occasionally forgetting a name and remembering it later is normal. Forgetting common words or losing track of conversations regularly is worth a doctor's appointment.
Can dementia be reversed?
Some causes — vitamin deficiency, thyroid disease, medication side effects, depression, normal-pressure hydrocephalus — can be reversed or substantially improved. Alzheimer's and most other neurodegenerative dementias cannot be reversed but can be slowed and managed.
How long does dementia last?
Average life expectancy from diagnosis is 8–10 years for Alzheimer's, but ranges widely. Lewy body and frontotemporal forms often progress faster.

Every dementia journey is different.

Memory Lane Care helps you understand what applies to your loved one, what to expect next, and which resources fit your family's situation.

Related across the journey

Memory Lane connects every part of dementia care. Here's how this topic threads into the rest.

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