ICD-10 Code for Unspecified Dementia
The ICD-10 diagnosis code for unspecified dementia is F03.90 (unspecified dementia without behavioral disturbance) or F03.91 (unspecified dementia with behavioral disturbance). 1
When to Use Unspecified Dementia Codes
Use F03.90 or F03.91 only when the underlying etiology of dementia cannot be determined despite appropriate diagnostic evaluation. 1 This represents a diagnosis of exclusion after ruling out specific dementia subtypes.
Appropriate Clinical Scenarios
- When diagnostic evaluation has been completed but the specific pathology (Alzheimer's disease, vascular dementia, Lewy body dementia, frontotemporal dementia) cannot be definitively established 2
- When mixed etiology dementia is present but no single pathology predominates sufficiently to warrant a primary disease classification 2
- When patients present with atypical or non-amnestic symptoms that don't fit standard diagnostic criteria for specific dementia types 2
Critical Coding Pitfall to Avoid
The unspecified dementia code (F03.90/F03.91) is substantially overused in clinical practice, leading to underestimation of specific dementia prevalence. 3 A study in the VA New England healthcare system found that 42.5% of first dementia diagnoses used the nonspecific code, and nearly half of individuals with persistent "unspecified dementia" actually met criteria for a specific dementia subtype upon chart review. 3
Why This Matters
- Primary care physicians performed cognitive testing only 12% of the time when first using the unspecified dementia code, compared to 98% for specialists 3
- Access to dementia specialists (geriatricians, neurologists) significantly reduced inappropriate use of nonspecific codes 3
- Proper diagnostic workup should establish the underlying pathology to determine the specific F code classification, rather than defaulting to the unspecified code. 1
Preferred Alternative: Specific Dementia Codes
When the underlying etiology can be identified, use these specific codes instead:
- F02.81: Dementia in other diseases classified elsewhere with behavioral disturbance (used for Alzheimer's disease with behavioral symptoms) 1
- F01.51: Vascular dementia with behavioral disturbance (when cerebrovascular disease is the primary etiology) 1
- Lewy body dementia codes: When fluctuating cognition, visual hallucinations, and behavioral symptoms are present 1
Documentation Requirements
- The underlying pathology determines the specific classification, not just the clinical presentation 1
- For mixed etiology dementia, document all contributing pathologies with the primary disease code listed first, followed by F02.81 1
- Use validated assessment tools (NPI-Q, CMAI, CSDD, GAI, or PSWQ-A) to systematically assess behavioral symptoms 1
Behavioral Disturbance Modifier
Add the behavioral disturbance modifier (.91 instead of .90) when patients exhibit agitation, aggression, wandering, sexual disinhibition, mood fluctuations, apathy, social withdrawal, or socially unacceptable behaviors. 1 This distinction is clinically important for care planning and resource allocation.