Harvard Mental Health Letter

The Quirky Brain: Theories about what causes chemobrain

A type of cognitive impairment known as "chemobrain" or "chemofog" is a common side effect of chemotherapy and other cancer treatments. A review of outcomes for adults treated with chemotherapy for solid tumors (such as those in the breast and prostate) found that 15% to 45% developed cognitive impairment, although impairment was usually subtle and short-lived.

The research suggests that many types of thinking ability are affected, including memory, processing speed, attention, concentration, and executive function (ability to plan and make decisions). For most people, these deficits subside with time, but in a minority they persist.

It is likely that multiple factors contribute to the development of chemobrain. The most obvious is cancer drug treatment itself. Although most chemotherapy agents do not cross the blood-brain barrier, some agents do — and may damage neurons and other brain cells.

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