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Non-Alzheimer dementias: Lewy body, frontotemporal and vascular
Each type of dementia starts at a different "address" in the brain and therefore with a different symptom: in dementia with Lewy bodies — fluctuating alertness, visual hallucinations, REM sleep behaviour disorder and parkinsonism; in frontotemporal dementia — a change in behaviour or language at a relatively young age; and in vascular dementia — impaired attention and processing speed with a stepwise course and vascular risk factors.
Why it matters in the exam
The exam gives a clinical description and asks for the type. The classic Lewy body question: a patient with hallucinations who received haloperidol and deteriorated badly (severe neuroleptic sensitivity). In frontotemporal dementia: a person in their 50s–60s with disinhibition, apathy, loss of empathy, overeating and compulsive behaviour, with relatively preserved memory.
Recurring points: the "one-year rule" — if cognitive decline comes first or within one year of the motor signs, the diagnosis is Lewy body dementia; if it starts more than a year after established parkinsonism, it is Parkinson disease dementia; in Lewy body dementia cholinesterase inhibitors help particularly well, and when an antipsychotic cannot be avoided, a low dose of quetiapine or clozapine is chosen; in frontotemporal dementia cholinesterase inhibitors do not help and may worsen behaviour, and SSRIs help behaviour.
In vascular dementia candidates are also asked about the link to small silent strokes and white matter damage, and about the frequent combination of vascular changes and Alzheimer disease in the same patient ("mixed dementia"). In the language forms of frontotemporal dementia the patient loses the meaning of words or the fluency of speech, while memory for events is relatively preserved early in the disease.
Key points
- Lewy body: fluctuations, visual hallucinations, REM sleep behaviour disorder, parkinsonism; neuroleptic sensitivity.
- The one-year rule separates Lewy body dementia from Parkinson disease dementia.
- Frontotemporal: change in behaviour or language, relatively young age, relatively preserved memory.
- Vascular: stepwise course, attention and speed, vascular risk factors.
- Cholinesterase inhibitors — yes in Lewy body and Parkinson disease dementia; no in frontotemporal dementia.
Summary table
| Type | Main picture | Tests | Treatment and exam point |
|---|---|---|---|
| Lewy body | Fluctuations, visual hallucinations, REM sleep behaviour disorder, parkinsonism | Reduced DaT-SPECT, reduced cardiac MIBG, polysomnography | Cholinesterase inhibitors; avoid haloperidol |
| Frontotemporal — behavioural | Disinhibition, apathy, loss of empathy, overeating, compulsions | Frontal and anterior temporal atrophy | SSRI for behaviour; no cholinesterase inhibitors |
| Frontotemporal — language | Semantic or non-fluent aphasia | Anterior temporal or left frontal atrophy | Speech and language therapy |
| Vascular | Stepwise course, attention and processing speed, focal signs | MRI: infarcts, white matter disease | Treat vascular risk factors |
| Parkinson disease dementia | Appears more than a year after parkinsonism | Clinical diagnosis | Rivastigmine |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Geriatrics, Medical licensing exam (IMLE), Internal medicine, Neurology, Psychiatry.
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Sources
- Fourth consensus report of the DLB Consortium — Diagnosis and management of dementia with Lewy bodies, 2017 — Core clinical features and biomarkers
- International consensus criteria for behavioural variant frontotemporal dementia, 2011 — Diagnostic criteria
- Hazzard's Geriatric Medicine and Gerontology, 8th edition (2022) — Alzheimer disease and other dementias
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Dementia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.