Dementia due to diseases classified elsewhere

The following categories for Dementia associated with other diseases or conditions known to cause Dementia are available:

• 6D85.0 Dementia due to Parkinson disease
• 6D85.1 Dementia due to Huntington disease
• 6D85.2 Dementia due to exposure to heavy metals and other toxins
• 6D85.3 Dementia due to human immunodeficiency virus
• 6D85.4 Dementia due to multiple sclerosis
• 6D85.5 Dementia due to prion disease
• 6D85.6 Dementia due to normal pressure hydrocephalus
• 6D85.7 Dementia due to injury to the head
• 6D85.8 Dementia due to pellagra
• 6D85.9 Dementia due to Down syndrome
• 6D85.Y Dementia due to other specified diseases classified elsewhere

For presentations characterized by marked impairment in two or more cognitive domains relative to that expected given the individual’s age and general premorbid level of neurocognitive functioning whose cause is identified and listed elsewhere in the ICD-11, but is not adequately captured by any of the other available Dementia categories, the following diagnosis may be appropriate:

6D85.Y Dementia Due to Other Specified Diseases Classified Elsewhere

• All diagnostic requirements for Dementia are met.
• The Dementia is presumed to be attributable to an underlying Disease of the Nervous System, trauma, infection, tumour, or other disease process affecting specific areas of the brain that is listed in the ICD-11 but is not adequately captured by any of the other available Dementia categories, as demonstrated by neuropsychological test data, neuroimaging data, genetic testing, medical tests, family history, and/or clinical history.
• This judgment depends on establishing that:
• The specified cause is known to be capable of producing the symptoms; and
• The course of the impairment (e.g., onset, trajectory of symptoms, response to treatment) is consistent with that known to be associated with the specified cause.

Note: The ICD-11 diagnosis corresponding to the presumed etiology should also be assigned.