ICD-10 Code G31.84 – Mild cognitive impairment of uncertain or unknown etiology (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G31.84 – Mild cognitive impairment of uncertain or unknown etiology
What it is
G31.84 identifies mild cognitive impairment when the cause is not known. Use it for documented cognitive decline that is greater than expected for age but does not meet criteria for dementia.
Clinical signs
Typical findings include memory or other cognitive complaints with objective impairment on testing, while daily independence is mostly preserved. Clinical features vary; refer to documentation.
When to use this code
Use this code when the record specifically states mild cognitive impairment and no clear underlying cause is documented. It also fits cases described as MCI, amnestic MCI, or nonamnestic MCI when the etiology remains uncertain. Check documentation if the note suggests another diagnosed neurologic or psychiatric condition.
Do not use for
Do not use G31.84 for dementia, delirium, or normal age-related forgetfulness. If the provider documents a known cause of cognitive decline, code the confirmed condition instead.
Coding tip
Code the documented diagnosis exactly and verify that the provider has not linked the impairment to a specific disease.