F02.C18 Dementia in other diseases classified elsewhere, severe, with other behavioral disturbance

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Dementia in other diseases classified elsewhere, severe, with behavioral disturbances such as sleep disturbance, social disinhibition, or sexual disinhibition
• Major neurocognitive disorder in other diseases classified elsewhere, severe, with behavioral disturbances such as sleep disturbance, social disinhibition, or sexual disinhibition

Use additional code

• code, if applicable, to identify wandering in dementia in conditions classified elsewhere (Z91.83)

Applies from F02 Dementia in other diseases classified elsewhere

Includes

• Major neurocognitive disorder in other diseases classified elsewhere

Excludes1 (never code together)

• mild neurocognitive disorder due to known physiological condition with or without behavioral disturbance (F06.7-)

Excludes2 (not included here)

• dementia in alcohol and psychoactive substance disorders (F10-F19, with .17, .27, .97)
• vascular dementia (F01.5-, F01.A-, F01.B-, F01.C-)

Code first

• the underlying physiological condition, such as:
• Alzheimer's (G30.-)
• cerebral lipidosis (E75.4)
• Creutzfeldt-Jakob disease (A81.0-)
• epilepsy and recurrent seizures (G40.-)
• frontotemporal dementia (G31.09)
• hepatolenticular degeneration (E83.01)
• human immunodeficiency virus [HIV] disease (B20)
• Huntington's disease (G10)
• hypercalcemia (E83.52)
• hypothyroidism, acquired (E00-E03.-)
• intoxications (T36-T65)
• Jakob-Creutzfeldt disease (A81.0-)
• multiple sclerosis (G35-)
• neurocognitive disorder with Lewy bodies (G31.83)
• neurosyphilis (A52.17)
• niacin deficiency [pellagra] (E52)
• other frontotemporal neurocognitive disorder (G31.90)
• Parkinson's disease (G20.-)
• Pick's disease (G31.01)
• polyarteritis nodosa (M30.0)
• prion disease (A81.9)
• systemic lupus erythematosus (M32.-)
• traumatic brain injury (S06.-)
• trypanosomiasis (B56.-, B57.-)
• vitamin B deficiency (E53.8)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 125 — Dementia, Severe
• RxHCC V08: HCC 112 — Dementia, Except Alzheimer's Disease
• ESRD V24: HCC 51

MS-DRG index

Defines the logic of DRG(s) 884 in MDC 19.

Medicare Code Edits (MCE v43.1 (April 2026))

• Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.

Code annotations containing back-references to F02.C18

Back-references to F02.C1

• Use Additional: A81 Atypical virus infections of central nervous system ("dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)")
• Use Additional: G10 Huntington's disease ("dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)")
• Use Additional: G20 Parkinson's disease ("dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)")
• Use Additional: G30 Alzheimer's disease ("dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)")
• Use Additional: G31 Other degenerative diseases of nervous system, not elsewhere classified ("dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)")

Back-references to F02

• Type 2 Excludes: F06 Other mental disorders due to known physiological condition ("dementia as classified in F01-F02")
• Type 1 Excludes: F06.7 Mild neurocognitive disorder due to known physiological condition ("dementia (F01.-, F02.-, F03.-)")
• Type 2 Excludes: F63.1 Pyromania ("mental disorders due to known physiological condition (F01-F09)")
• Type 2 Excludes: F63.2 Kleptomania ("stealing in mental disorders due to known physiological condition (F01-F09)")
• Type 1 Excludes: G31.84 Mild cognitive impairment of uncertain or unknown etiology ("dementia (F01.-, F02.-, F03.-)")

Diagnosis Index entries for F02.C18

• Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › in (due to) › diseases specified elsewhere (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › severe › with › behavioral disturbances (sexual disinhibition) (sleep disturbance) (social disinhibition)
• Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › in (due to) › diseases specified elsewhere (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › severe › with › behavioral disturbances (sexual disinhibition) (sleep disturbance) (social disinhibition) › specified NEC

Nearby codes

• F02.B4 Dementia in other diseases classified elsewhere, moderate, with anxiety
• F02.C Dementia in other diseases classified elsewhere, severe
• F02.C0 Dementia in other diseases classified elsewhere, severe, without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety
• F02.C1 Dementia in other diseases classified elsewhere, severe, with behavioral disturbance
• F02.C11 Dementia in other diseases classified elsewhere, severe, with agitation
• F02.C18 Dementia in other diseases classified elsewhere, severe, with other behavioral disturbance (this code)
• F02.C2 Dementia in other diseases classified elsewhere, severe, with psychotic disturbance
• F02.C3 Dementia in other diseases classified elsewhere, severe, with mood disturbance
• F02.C4 Dementia in other diseases classified elsewhere, severe, with anxiety