Figure 1
Figure 1From Alzheimer's Research & Therapy · CC BY
Brain agingHumans

Probable REM sleep disorder links to Lewy body dementia

In a memory clinic cohort, probable REM sleep behaviour disorder was linked to incident Lewy body dementia with a hazard ratio of 4.82.

Alzheimer's Research & Therapy

In memory clinic patients and community-dwelling older adults, researchers evaluated whether a brief questionnaire for probable REM sleep behaviour disorder identifies risk for Lewy body dementia. The study examined 619 memory clinic patients followed for a median of 3.4 years and 5,274 community cohort participants followed for 6.4 years. Probable REM sleep behaviour disorder required reported dream-enactment behaviour alongside complex nocturnal motor behaviours. Among memory clinic attendees, 14.7% of those screening positive developed Lewy body dementia compared with 3.6% who screened negative, representing a cause-specific hazard ratio of 4.82. However, the screen showed no association with all-cause dementia in either the clinic or the community cohort. Out of 26 incident Lewy body dementia cases in the clinic, 23 were dementia with Lewy bodies and three were Parkinson's disease dementia.

Why it matters

REM sleep behaviour disorder is considered an early clinical marker of alpha-synucleinopathies during aging. Demonstrating subtype-specific risk using brief screening criteria could help prioritize aging individuals for targeted neurological evaluations.

Caveats

The clinic findings rest on only 26 Lewy body dementia cases in a cohort where only a minority of registered patients returned for follow-up. Additionally, the study relied on a questionnaire algorithm rather than polysomnography-confirmed sleep disorder diagnoses.

The paper

Criteria-based probable REM sleep behaviour disorder and risk of Lewy body dementia: analyses of a memory clinic cohort and a community cohort

Han JW, Oh DJ, Choi YJ et al.

Alzheimer's Research & Therapy · 2 Oct 2026

doi.org/10.1186/s13195-026-02207-0

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