Although the theory about chemotherapy causing cognitive problems in patients had been once dismissed, the researchers showed again that chemo does cause changes in the brain by killing the healthy nerve cells and causes side effects like forgetfulness, seizures, vision loss and dementia.

A professor at the University of Rochester Medical Center, Mark Noble, reports that cancer drugs proved to be more toxic to healthy cells than to malignant ones. Chemo drugs killed 40% to 80% of cancer cells and even 70% to 100% of healthy brain cells.

Three most common chemo drugs — cisplatin, cytarabine and carmustine were tested. Some of the healthy brain cells affected by the chemotherapy continued to die for several weeks after treatment.

The head of UCLA's neuronuclear imaging section, dr. Silverman says that the previous reports do not prove that killing brain cells causes cognitive problems and that additional experiments should be conducted to see if the rats who lost brain cells had bigger problems than the others in solving intelligence tasks.