Cognitive impairment occurs when there is a problem with perceiving, thinking, or remembering. Strokes are a common cause of cognitive impairment. Other causes include head injuries and some chronic diseases, such as Parkinson's disease or multiple sclerosis. Cognitive impairment can vary from mild to severe depending on the cause.

Cognitive impairment may cause problems with:

• Memory, especially short-term memory.
• Problem solving.
• Attention span, especially in a mental task such as a math calculation.
• Expressing oneself. An example is finding the right words to use in a conversation.
• Behaviour or judgment. An example is being more impulsive.

Treatment options for cognitive impairment depend on the cause.