6D80

Dementia due to Alzheimer disease

Description

Dementia due to Alzheimer disease is the most common form of dementia. Onset is insidious with memory impairment typically reported as the initial presenting complaint. The characteristic course is a slow but steady decline from a previous level of cognitive functioning with impairment in additional cognitive domains (such as executive functions, attention, language, social cognition and judgment, psychomotor speed, visuoperceptual or visuospatial abilities) emerging with disease progression. Dementia due to Alzheimer disease may be accompanied by mental and behavioural symptoms such as depressed mood and apathy in the initial stages of the disease and may be accompanied by psychotic symptoms, irritability, aggression, confusion, abnormalities of gait and mobility, and seizures at later stages. Positive genetic testing, family history and gradual cognitive decline are suggestive of Dementia due to Alzheimer disease. [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 Alzheimer Disease (8A20) based on quantified clinical assessment or standardized neuropsychological/cognitive testing, neuroimaging data, genetic testing, medical tests, family history, and/or clinical history.
Early clinical history is typically characterized by gradual onset, progressive memory problems and word finding difficulties, as well as mild functional impairment. The most common form of Alzheimer Disease begins with neuronal impairment in the medial temporal lobes (the brain regions involved in memory formation). As Alzheimer Disease progresses and affects other brain regions, neurocognitive symptoms worsen. Atypical forms of Alzheimer Disease are also characterized by progressive neurocognitive and functional impairment, with initial neurocognitive symptoms often corresponding to the brain region(s) initially affected (e.g., visual processing impairment in posterior cortical atrophy, etc.).

Note: For all forms of Dementia due to Alzheimer Disease, the diagnosis 8A20 Alzheimer Disease should also be assigned.

For Dementia Due to Alzheimer Disease whose onset is unknown or unspecified, the following diagnosis may be appropriate:

6D80.Z Dementia Due to Alzheimer Disease, onset unknown or unspecified

All diagnostic requirements for Dementia Due to Alzheimer Disease are met.
The onset of neurocognitive, functional, and/or behavioural symptoms associated with Alzheimer Disease is unknown or unspecified.

Subcategories

6D80.0 Dementia due to Alzheimer disease with early onset

Dementia due to Alzheimer disease in which symptoms emerge before the age of 65 years. It is relatively rare, representing less than 5% of all cases, and may be genetically determined (autosomal dominant Alzheimer disease). Clinical presentation may be similar to cases with later onset, but progression of cognitive deficits may be more rapid. [1]
- All diagnostic requirements for Dementia Due to Alzheimer Disease are met.
- Neurocognitive, functional, and or behavioural symptoms associated with Alzheimer Disease were present prior to age 65, as evidenced by neuropsychological test data, neuroimaging data, genetic testing, medical tests, family history, and/or clinical history.
6D80.1 Dementia due to Alzheimer disease with late onset

Dementia due to Alzheimer disease that develops at the age of 65 years or above. This is the most common pattern, representing more than 95% of all cases. [1]
- All diagnostic requirements for Dementia Due to Alzheimer Disease are met.
- Neurocognitive, functional, and or behavioural symptoms associated with Alzheimer Disease were present at or after age 65, as evidenced by neuropsychological test data, neuroimaging data, genetic testing, medical tests, family history, and/or clinical history.
6D80.2 Alzheimer disease dementia, mixed type, with cerebrovascular disease

Dementia due to Alzheimer disease and concomitant cerebrovascular disease. [1]
- All diagnostic requirements for Dementia Due to Alzheimer Disease are met.
- Neurocognitive, functional, and/or behavioural symptoms of Dementia appear to be partially related to co-existing cerebrovascular disease, as demonstrated by neuroimaging, medical tests, and/or by clinical history of cerebrovascular disease.
- Clinical course of neurocognitive and functional impairment is progressive, and typically characterized by combined impairment in so-called cortical cognitive functions (e.g., memory, language, and/or visuospatial skills) and so-called subcortical cognitive functions (e.g., attention, processing speed, and executive/frontal lobe-related functioning).
6D80.3 Alzheimer disease dementia, mixed type, with other nonvascular aetiologies

Dementia due to Alzheimer disease with other concomitant pathology, not including cerebrovascular disease. [1]
- All diagnostic requirements for Dementia Due to Alzheimer Disease are met.
- Neurocognitive, functional, and/or behavioural symptoms of Dementia appear to be partially related to a known co-morbid aetiology, as demonstrated by neuroimaging data, genetic testing, medical tests, family history, medical history, and/or clinical history.

References

World Health Organization. International Classification of Diseases, 11th Revision, for Mortality and Morbidity Statistics (ICD-11 MMS), 2026-01 release. World Health Organization; 2026.
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.