Antioxidant shows promise for "chemo-brain"

NEW YORK (Reuters Health) - A new animal study suggests that antioxidant therapy may prevent the memory and attention problems that plague many cancer patients undergoing chemotherapy.

Often called “chemo-brain,” such mental side effects are seen in up to 70 percent of chemotherapy patients by some estimates.

In the new study, researchers at West Virginia University School of Medicine in Morgantown looked at whether injections of a powerful antioxidant called N-acetyl cysteine, or NAC, could prevent chemo-related memory changes in rats.

The researchers first exposed one group of rats to two drugs commonly used to treat cancer, Adriamycin and Cytoxan. They found that compared with a group of control animals, the chemo-exposed rats showed a decline in standard tests of rodent memory.

However, that mental fog was completely prevented when the researchers gave the rats NAC injections three times per week during chemotherapy administered four times per week.

The findings, published in the journal Metabolic Brain Disease, are promising. But it is far too soon for chemotherapy patients to turn to antioxidants for preventing chemo-brain, according to lead researcher Dr. Gregory W. Konat.

“I wouldn’t suggest that patients do anything now,” he told Reuters Health. More lab research is needed before NAC can even be moved into human clinical trials, let alone be given to patients, Konat said.

Chemotherapy patients should also not take large doses of other commonly available antioxidants, like vitamin C, according to the researcher.

Konat noted that a long-standing concern with antioxidants is that they could theoretically interfere with the effectiveness of chemotherapy.

Antioxidants protect cells by neutralizing cell-damaging substances called oxygen free radicals; it’s thought that this damage, known as oxidative stress, may be what’s responsible for the mental side effects of chemotherapy.

However, it’s also thought that chemotherapy kills cancer cells, at least in part, by creating oxidative stress. So in theory, taking antioxidants could weaken the cancer-fighting ability of chemotherapy drugs.

A recent analysis of past studies suggests that antioxidants do not, in fact, diminish the effectiveness of chemotherapy, Konat said.

Still, he added, caution is in order. “We’re dealing with a very serious condition here,” he pointed out.

Given the unknowns, Konat advises chemotherapy patients to not self-treat with antioxidants or take any supplement without talking to their doctors first.

SOURCE: Metabolic Brain Disease, September 2008.