The Types of Dementia Explained (2026)

Dementia isn't one illness — it's an umbrella term for a group of conditions that damage the brain and affect memory, thinking, mood or behaviour. If someone you love has just been diagnosed, or you're waiting for an assessment, knowing which type is involved helps you understand what to expect and what support to look for.

How common is each type of dementia?

Estimates vary between studies, but Alzheimer's Society gives a broad picture of how the main types compare. Treat the numbers below as approximate — many people are told they have "mixed" dementia rather than a single, clear-cut type.

What is Alzheimer's disease?

Alzheimer's disease is caused by abnormal build-ups of protein in the brain, which gradually damage brain cells. It's the most common cause of dementia and tends to progress slowly and steadily over several years.

Memory loss — especially for recent events — is usually the first sign families notice. Over time, thinking, language, orientation and, eventually, physical abilities are also affected. See NHS — dementia for more on symptoms and stages.

What is vascular dementia?

Vascular dementia happens when the brain's blood supply is reduced or interrupted, often after a stroke or a series of small strokes, or because of long-term damage to small blood vessels. It's the second most common type.

Symptoms can appear suddenly after a stroke, or build up gradually. Unlike Alzheimer's steady slide, vascular dementia can progress in noticeable "steps" — a period of stability, then a sudden drop, often linked to a new vascular event.

Alzheimer's vs vascular dementia — how do they differ?

The two conditions can look similar day to day, and it's common for someone to have both. But there are useful differences to be aware of:

What is mixed dementia?

Mixed dementia means someone has more than one type at once — most often Alzheimer's disease alongside vascular changes. It's especially common in older people. In practice, a mixed diagnosis doesn't always change day-to-day care, but it can affect which treatments a doctor recommends and how the condition is likely to progress.

What is Lewy body dementia?

Lewy body dementia is caused by abnormal protein deposits ("Lewy bodies") in the brain — the same type found in Parkinson's disease, which is why the two conditions often overlap. Distinctive features include:

• Visual hallucinations, sometimes early on
• Alertness and confusion that fluctuate noticeably, even hour to hour
• Movement problems similar to Parkinson's — slowness, stiffness, falls
• Disturbed sleep, including acting out dreams

People with Lewy body dementia can react badly to certain antipsychotic medicines, so a correct diagnosis matters a great deal here. If hallucinations or unexplained falls appear alongside memory problems, mention this specifically to the GP.

What is frontotemporal dementia?

Frontotemporal dementia (FTD) affects the frontal and temporal lobes of the brain — the areas involved in personality, behaviour, judgement and language. It's less common than Alzheimer's or vascular dementia, and it tends to affect people at a younger age, often in their 50s and 60s.

Memory is often relatively preserved in the early stages. Instead, families notice changes in personality (becoming withdrawn, disinhibited or apathetic), difficulty finding words, or a loss of social judgement. Because these signs look more like a mental health problem or mid-life change than "classic" dementia, FTD is sometimes diagnosed later than it should be.

Other, rarer types of dementia

• Parkinson's disease dementia — develops in some people who have had Parkinson's disease for several years, with symptoms similar to Lewy body dementia.
• Alcohol-related brain damage — including Korsakoff's syndrome, caused by long-term heavy drinking and thiamine (vitamin B1) deficiency.
• Young-onset dementia — any type of dementia diagnosed before age 65; often frontotemporal dementia, but can be Alzheimer's or vascular dementia too.

Dementia UK, which runs the Admiral Nurse service, is a good source of specialist support for rarer or younger-onset diagnoses.

Why does the type of dementia matter for care and treatment?

Getting a specific diagnosis, rather than just "dementia" as a label, matters for several practical reasons:

• Medication — some drugs used for Alzheimer's disease aren't suitable, or need care, for people with Lewy body dementia.
• Managing risk factors — vascular dementia is closely linked to blood pressure, cholesterol and diabetes, so controlling these can help slow progression.
• Planning ahead — knowing the likely pattern (steady decline versus stepped, or early behaviour change versus early memory loss) helps families plan care, finances and legal arrangements, including setting up a lasting power of attorney while the person can still make decisions.
• Choosing the right care setting — a home experienced in supporting hallucinations and mobility issues (Lewy body) may suit differently to one focused on memory support (Alzheimer's) or behaviour changes (FTD).

How is dementia diagnosed?

Diagnosis usually starts with a GP, who will ask about symptoms, check general health, and may run blood tests to rule out other causes of confusion, such as thyroid problems or vitamin deficiencies. Most people are then referred to a memory clinic or specialist for further assessment, which can include memory and thinking tests and, sometimes, a brain scan. See the NHS social care and support guide for what happens after a diagnosis, and NICE for clinical guidance used by specialists.