A syndrome referred to as 'chemo brain,' characterized by reduced cognitive function, seizures and other neurological problems, may have more to do with the side effects of certain drugs used to treat cancer than with the debilitating effects of the disease itself.

The drugs have been linked to such side effects as reduced cognitive function, seizures and loss of brain cells.

Dr. Mark Noble and colleagues of the University of Rochester found that the drugs killed neural stem cells and compromised neural stem cell division in experiments with mice.

They also destroyed oligodendrocytes, which produce myelin insulation that is critical for sending messages throughout the nervous system.

The mice in the study continued losing brain cells as long as six weeks following administration of the chemo drugs, the team reported.

In addition to the mouse experiments, the scientists tested neural cells and cancer cells from humans.

The chemo drugs were more destructive to the neural cells than to the cancer cells, they observed.

While they killed 40 percent to 80 percent of the cancer cells, they destroyed 70 percent to 100 percent of the human brain cells.

In a separate study published in the journal Cancer, a team of researchers in Japan found that patients receiving chemotherapy for breast cancer experienced shrinkage of brain regions involved in memory and concentration. However, the effect was temporary.