ICD-11 Criteria for Dementia due to Diseases Classified Elsewhere (6D85 ) (2023)

CodingNote: Thiscategory should never be used in primary tabulation. The codes are provided foruse as supplementary or additional codes when it is desired to identify thepresence of dementia in diseases classified elsewhere.

When dementia is due to multiple aetiologies,code all that apply.

6D85.0 Dementiadue to Parkinson disease

Dementia due to Parkinson diseasedevelops among individuals with idiopathic Parkinson disease and ischaracterized by impairment in attention, memory, executive and visuo-spatialfunctions. Mental and behavioral symptoms such as changes in affect, apathy andhallucinations may also be present. Onset is insidious and the course is one ofgradual worsening of symptoms.

When dementia is due to multipleaetiologies, code all that apply.

6D85.1 Dementiadue to Huntington disease

Dementia due to Huntington diseaseoccurs as part of a widespread degeneration of the brain due to a trinucleotiderepeat expansion in the HTT gene, which is transmitted through autosomaldominance. Onset of symptoms is insidious typically in the third and fourthdecade of life with gradual and slow progression. Initial symptoms typicallyinclude impairments in executive functions with relative sparing of memory,prior to the onset of motor deficits (bradykinesia and chorea) characteristicof Huntington disease.

When dementia is due to multipleaetiologies, code all that apply.

Inclusions:

Dementiain Huntington chorea

6D85.2 Dementiadue to exposure to heavy metals and other toxins

Dementia due to exposure to heavymetals and other toxins caused by toxic exposure to specific heavy metals suchas aluminium from dialysis water, lead, mercury or manganese. Thecharacteristic cognitive impairments in Dementia due to exposure to heavymetals and other toxins depend on the specific heavy metal or toxin that theindividual has been exposed to but can affect any cognitive domain. Onset ofsymptoms is related to exposure and progression can be rapid especially withacute exposure. In many cases, symptoms are reversible when exposure isidentified and ceases. Investigations such as brain imaging orneurophysiological testing may be abnormal. Lead poisoning is associated withabnormalities on brain imaging including widespread calcification and increasedsignal on MRI T2-weighted images of periventricular white matter, basal gangliahypothalamus and pons. Dementia due to aluminium toxicity may demonstratecharacteristic paroxysmal high-voltage delta EEG changes. Examination may makeevident other features such as peripheral neuropathy in the case of lead,arsenic, or mercury.

Exclusions:

Dementiadue to psychoactive substances including medications (6D84)

6D85.3 Dementiadue to human immunodeficiency virus

Dementia due to humanimmunodeficiency virus develops during the course of confirmed HIV disease, inthe absence of a concurrent illness or condition other than HIV infection thatcould explain the clinical features. Although a variety of patterns ofcognitive deficit are possible depending on where the HIV pathogenic processeshave occurred, typically deficits follow a subcortical pattern with impairmentsin executive function, processing speed, attention, and learning newinformation. The course of Dementia due to human immunodeficiency virus variesincluding resolution of symptoms, gradual decline in functioning, improvement,or fluctuation in symptoms. Rapid decline in cognitive functioning is rare withthe advent of antiretroviral medications.

When dementia is due to multipleaetiologies, code all that apply.

6D85.4 Dementiadue to multiple sclerosis

Dementia due to multiple sclerosisis a neurodegenerative disease due to the cerebral effects of multiplesclerosis, a demyelinating disease. Onset of symptoms is insidious and notsecondary to the functional impairment attributable to the primary disease(i.e., multiple sclerosis). Cognitive impairments vary according to thelocation of demyelination but typically include deficits in processing speed,memory, attention, and aspects of executive functioning.

CodingNote: Thiscategory should never be used in primary tabulation. The codes are provided foruse as supplementary or additional codes when it is desired to identify thepresence of dementia in diseases classified elsewhere.

When dementia is due to multipleaetiologies, code all that apply.

6D85.5Dementiadue to prion disease

Dementia due to prion disease is aprimary neurodegenerative disease caused by a group of spongiformencephalopathies resulting from abnormal prion protein accumulation in thebrain. These can be sporadic, genetic (caused by mutations in the prion-proteingene), or transmissible (acquired from an infected individual). Onset isinsidious and there is a rapid progression of symptoms and impairmentcharacterised by cognitive deficits, ataxia, and motor symptoms (myoclonus,chorea, or dystonia). Diagnosis is typically made on the basis of brain imagingstudies, presence of characteristic proteins in spinal fluid, EEG, or genetictesting.

When dementia is due to multipleaetiologies, code all that apply.

6D85.6 Dementiadue to normal pressure hydrocephalus

Dementia due to normal pressurehydrocephalus results from excess accumulation of cerebrospinal fluid in thebrain as a result of idiopathic, non-obstructive causes but can also besecondary to haemorrhage, infection or inflammation. Progression is gradual butintervention (e.g., shunt) may result in improvement of symptoms, especially ifadministered earlier in the course of the condition. Typically, cognitiveimpairments include reduced processing speed and deficits in executivefunctioning and attention. These symptoms are also typically accompanied bygait abnormalities and urinary incontinence. Brain imaging to revealventricular volume and characterize brain displacement is often necessary toconfirm the diagnosis.

When dementia is due to multipleaetiologies, code all that apply.

6D85.7Dementiadue to injury to the head

Dementia due to injury to the headis caused by damage inflicted on the tissues of the brain as the direct orindirect result of an external force. Trauma to the brain is known to haveresulted in loss of consciousness, amnesia, disorientation and confusion, orneurological signs. The symptoms characteristic of Dementia due to injury tothe head must arise immediately following the trauma or after the individualgains consciousness and must persist beyond the acute post-injury period.Cognitive deficits vary depending on the specific brain areas affected and theseverity of the injury but can include impairments in attention, memory,executive functioning, personality, processing speed, social cognition, andlanguage abilities.

When dementia is due to multiple aetiologies,code all that apply.

6D85.8 Dementiadue to pellagra

Dementia due to pellagra is causedby persistent lack of vitamin B3 (niacin) or tryptophan either in the diet ordue to poor absorption in the gastrointestinal tract due to disease (e.g.,Crohn disease) or due to the effects of some medications (e.g., isoniazid).Core signs of pellagra include dermatological changes (sensitivity to sunlight,lesions, alopecia, and oedema) and diarrhoea. With prolonged nutritionaldeficiency cognitive symptoms that include aggressivity, motor disturbances(ataxia and restlessness), confusion, and weakness are observed. Treatment withnutritional supplementation (e.g., niacin) typically results in reversal ofsymptoms.

CodingNote: Codeaslo the causing condition

6D85.9 Dementiadue to Down syndrome

Dementia due to Down syndrome is aneurodegenerative disorder related to the impact of abnormal increasedproduction and accumulation of amyloid precursor protein (APP) leading toformation of beta-amyloid plaques and tau tangles. APP gene expression isincreased due to its location on chromosome 21, which is abnormally triplicatedin Down syndrome. Cognitive deficits and neuropathological features are similarto those observed in Alzheimer disease. Onset is typically after the fourthdecade of life with a gradual decline in functioning, and may impact 50% ormore of individuals with Down syndrome.

When dementia is due to multipleaetiologies, code all that apply.

6D85.YDementiadue to other specified diseases classified elsewhere

When dementia is due to multipleaetiologies, code all that apply.

REFERENCE:

International Classification of Diseases Eleventh Revision (ICD-11). Geneva: World Health Organization; 2022. License: CC BY-ND 3.0 IGO.

https://creativecommons.org/licenses/by-nc-nd/3.0/igo/