…Virtually all cancer survivors who have had toxic treatments like chemotherapy experience short-term memory loss and difficulty concentrating during and shortly afterward, experts say. But a vast majority improve. About 15 percent, or roughly 360,000 of the nation’s 2.4 million female breast cancer survivors, the group that has dominated research on cognitive side effects, remain distracted years later, according to some experts. And nobody knows what distinguishes this 15 percent.
… The central puzzle of chemo brain is that many of the symptoms can occur for reasons other than chemotherapy.
Abrupt menopause, which often follows treatment, also leaves many women fuzzy-headed in a more extreme way than natural menopause, which unfolds slowly. Those cognitive issues are also features of depression and anxiety, which often accompany a cancer diagnosis. Similar effects are also caused by medications for nausea and pain.
…’So many factors affect cognitive function, and the kinds of cognitive problems associated with cancer treatment can be caused by many other things than chemotherapy…’ ” (New York Times )