Dementia Types: How to Tell Them Apart

When the neurologist says 'dementia,' families often hear one word — Alzheimer's. In reality, dementia is an umbrella term for a group of brain conditions, and the four most common types look very different at home. Knowing which one your family member has changes the care plan, the medication conversation, and the timeline of what to expect.

This guide is the plain-language tour of the four most common dementia types — Alzheimer's, vascular, Lewy body, and frontotemporal — what each one tends to look like in the kitchen rather than the clinic, why the difference matters, and the questions to bring to the next neurology visit. No medical training required.

Alzheimer's Disease: memory for recent things, first

Alzheimer's disease is the most common form of dementia, accounting for the majority of cases in older adults. The hallmark at home is short-term memory loss — the same conversation three times in an afternoon, multiple missed appointments, a sense that a familiar word has dropped out. Long-term memory and personality often stay intact for years, which is why families sometimes describe it as 'still Dad, just repeating himself.'

Over time, other changes show up — trouble finding words, getting lost in familiar places, difficulty with planning and judgment. The decline is typically gradual rather than sudden changes. A diagnosis of Alzheimer's is usually made by a primary-care provider, a neurologist, or a geriatrician after a combination of history, cognitive testing, and sometimes imaging or blood work.

Vascular dementia: the step-down pattern

Vascular dementia is caused by impaired blood flow to the brain — often after a stroke, a series of small strokes (sometimes called 'silent strokes'), or chronic small-vessel disease. The pattern that families notice at home is different from Alzheimer's: changes tend to happen in steps rather than as a slow slope. A parent does relatively well, then has a sudden drop, then plateaus.

Symptoms depend on which part of the brain was affected. Memory may be preserved early on; executive function (planning, organizing, sequencing tasks) often takes the first hit. Slowed thinking, difficulty making decisions, and changes in walking or balance are common. Cardiovascular risk factors — blood pressure, diabetes, atrial fibrillation, smoking — drive the underlying disease.

Lewy body dementia: hallucinations, swings, and movement

Lewy body dementia (which includes both dementia with Lewy bodies and Parkinson's disease dementia) may go unnoticed, or misdiagnosed. The three features that tend to surface together: vivid visual hallucinations (often of small animals, children, or strangers in the house), big day-to-day fluctuations in alertness and confusion, and parkinsonian movement changes — tremor, stiffness, slowed movement, falls.

Lewy body dementia is also the one where certain medications — particularly some older antipsychotics — can cause severe reactions. Families with a Lewy body diagnosis are routinely advised to mention the diagnosis at every medical encounter and to carry a card or wallet note naming it. Movement and cognition usually do not progress in lock-step; the cognitive picture can change hour to hour.

Frontotemporal dementia: personality first, often younger

Frontotemporal dementia (FTD) is the least common of the four in absolute numbers but the most common dementia in adults under sixty-five. The hallmark is not memory loss — it is changes in personality, behavior, or language. A previously reserved parent becomes impulsive. A famously polite parent becomes blunt. A precise speaker starts groping for words. Memory for events can stay intact for years.

Because FTD often begins in midlife, the early signs are frequently misread as depression, midlife crisis, or a difficult workplace season. A diagnosis usually involves a neurologist familiar with the condition, structured interviews with the family (not just the patient), and brain imaging. The Association for Frontotemporal Degeneration is the largest U.S. patient organization for FTD.

What the differences mean for the care plan

Naming the type matters less for prognosis (which is often uncertain across all four) and more for the day-to-day care plan. Vascular dementia calls for aggressive management of cardiovascular risk factors. Lewy body dementia changes the medication safety conversation. Frontotemporal dementia reshapes the family meeting because the behavior changes are what needs to be addressed and managed. Alzheimer's frames the conversation about memory aides and routines.

• Bring a behavior journal, not just a memory listFor two to three weeks before the next neurology visit, write down what is changing — naming, behavior, mood, hallucinations, sleep, gait. The pattern over weeks is what the neurologist needs.
• Ask the type question directlyNot all primary-care providers will volunteer the type. Ask: 'Based on what you see, which type of dementia is most likely, and how confident are you?'
• Mixed dementia is realMany older adults have features of more than one type — most commonly Alzheimer's plus vascular. The care plan adapts to both, not just the label on the chart.
• Bring the family historianA sibling or spouse who has known the parent the longest will catch behavior changes the parent themselves cannot. The historian's report is part of the workup.
• Ask about Lewy body specifically if there are hallucinations or sleep movementsActing out dreams during sleep (REM sleep behavior disorder) can precede Lewy body dementia by years. It is worth mentioning even if memory looks fine.
• Plan for the 'mixed' answerMany families leave the visit with 'most likely Alzheimer's with some vascular changes.' The plan is shaped by both halves, not the dominant label.

For the broader first-month playbook this conversation feeds into, see The First 30 Days After a Dementia Diagnosis. For the longer pillar of related guides, the Dementia & Alzheimer's hub has the full set. Companion posts: What stage of dementia is my parent in? and Anosognosia: when your parent doesn't know they're sick.