ICD-10 Code F02.C18 – Dementia in other diseases classified elsewhere, severe, with other behavioral disturbance (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F02.C18 – Dementia in other diseases classified elsewhere, severe, with other behavioral disturbance
What it is
This code identifies severe dementia caused by another underlying disease, with behavioral disturbance documented. Use it when the dementia is not the primary disease and the record specifies a behavioral issue.
Clinical signs
Expect marked cognitive decline affecting daily function, with severe impairment in memory, judgment, or communication. Behavioral disturbance may include agitation, aggression, wandering, or other disruptive behavior; clinical features vary, refer to documentation.
When to use this code
Use this code when the provider documents dementia due to another condition and states that it is severe with other behavioral disturbance. The underlying disease should also be documented and coded as directed. Apply it when the chart clearly links the dementia to the secondary disease and describes the behavioral problem.
Do not use for
Do not use this code for unspecified dementia, mild or moderate dementia, or dementia without behavioral disturbance. If the cause or severity is unclear, check documentation.
Coding tip
Confirm both the underlying condition and the behavioral disturbance are explicitly documented before assigning F02.C18.