cognitively impaired

Cognitively impaired describes someone whose mental functions—memory, reasoning, attention, or learning—are diminished from typical levels.

The impairment may be permanent (from brain injury, dementia, or developmental conditions) or temporary (from medication, illness, or intoxication).

The phrase is clinical and neutral, often used in medical, educational, or legal contexts: services for cognitively impaired adults, The medication may leave you cognitively impaired.