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6D82

Dementia due to Lewy body disease

Description

Dementia preceding or occurring within one year after the onset of motor parkinsonian signs in the setting of Lewy body disease. Characterized by presence of Lewy bodies, which are intraneuronal inclusions containing α-synuclein and ubiquitin in the brain stem, limbic area, forebrain, and neocortex. Onset is insidious with attentional and executive functioning deficits often present. These cognitive deficits are often accompanied by visual hallucinations and symptoms of REM sleep behaviour disorder. Hallucinations in other sensory modalities, depressive symptoms, and delusions may also be present. The symptom presentation usually varies significantly over the course of days necessitating longitudinal assessment and differentiation from delirium. Spontaneous onset of Parkinsonism within approximately 1 year of the onset of cognitive symptoms is common. [1]

Diagnostic requirements

WHO clinical descriptions and diagnostic requirements [1,2].

  • All diagnostic requirements for Dementia are met.
  • Dementia is presumed to be attributable to underlying Lewy Body Disease as demonstrated by neuropsychological test data, neuroimaging data, genetic testing, medical tests, family history, and/or clinical history.
  • Clinical history involves the presence of two or more of the following symptoms:
    • Recurrent visual hallucinations (typically well-formed)
    • Episodic confusion
    • REM sleep behaviour disorder
    • One or more features of Parkinsonism (e.g., resting tremor)
  • Neurocognitive symptoms are progressive and often involve relatively greater impairment in visuospatial skills, attention, and executive functioning (as opposed to primary memory impairment, as is seen in Alzheimer Disease).
  • Additional clinical features may include repeated falls, syncope, hallucinations in other sensory modalities, delusions, and autonomic dysfunction (e.g., constipation, urinary incontinence, etc.).

Note: A diagnosis of 8A22 Lewy Body Disease should also be assigned.

References

  1. World Health Organization. International Classification of Diseases, 11th Revision, for Mortality and Morbidity Statistics (ICD-11 MMS), 2026-01 release. World Health Organization; 2026.
  2. World Health Organization. Clinical Descriptions and Diagnostic Requirements for ICD-11 Mental, Behavioural or Neurodevelopmental Disorders (CDDR). World Health Organization; 2024.

WHO text reproduced without changes from the WHO ICD-11 API. © World Health Organization, licensed under CC BY-ND 3.0 IGO. View this entry in the WHO ICD-11 browser.