MONDAY, Nov. 14 (HealthDay News) -- Researchers have homed in on which parts of the brain seem to be involved in "chemo brain," the memory problems and other impairments that often accompany chemotherapy treatments for breast cancer.

According to research in the November issue of the Archives of Neurology, those areas of the brain that are involved in planning, attention and memory performance were less robust in breast cancer patients who had undergone chemotherapy than in breast cancer patients who had not had chemotherapy or in healthy women who acted as study controls.

The findings are important not only to find ways to manage this side effect, but also to give credibility to women who report these effects and aren't taken seriously, said the authors of the report and another expert.

"There's been a controversy whether it's the disease itself or hormonal blockade medications or chemotherapy," said study lead author Shelli Kesler.

"A lot of women complain of problems but then perform in the normal range on subjective tests," explained Michelle Janelsins, a research assistant professor of radiation oncology at the James P. Wilmot Cancer Center at the University of Rochester Medical Center, in Rochester, N.Y.

"This is going to give us more information about what exactly is going on so that we can develop better management approaches," said Janelsins, who was not involved with the study.

According to the study authors, chemo brain is the most commonly reported neurological and cognitive problem among breast cancer patients who have received chemotherapy for their condition.

Janelsins said that much research has been devoted to chemo brain but, as of yet, few ways to actually alleviate it.

The researchers compared results from functional magnetic resonance imaging (fMRI) done on 25 women with breast cancer who had received chemotherapy, 19 women with breast cancer who had not undergone chemotherapy, and 18 healthy women.

The women performed a card-sorting task designed to measure problem-solving skills and also reported their own perception of their cognitive abilities.

Women with breast cancer, whether or not they had had chemotherapy, showed reduced activity in two areas of the prefrontal cortex, including one heavily involved in memory, the investigators found.

"The non-chemo group did show some brain changes but their actual performance of cognitive tasks was not impaired," said Kesler, who is an assistant professor of psychiatry and behavioral sciences at Stanford University School of Medicine. "For women who had chemo, their deficit, their brain change is more severe to the point where they are showing actual performance impairment on cognitive tests."

The group that had undergone chemotherapy also had reduced activity in the prefrontal cortex and tended to repeat errors and complete tasks more slowly compared to both other groups.

This reduced activity also correlated with how patients viewed their own abilities.

The worse the disease and the worse the women perceived their own functioning, the lower the activity.

"The pattern of brain activation actually matched up with self-report," said Janelsins. "That's important because a lot of times self-report measures aren't matching up with performance on some cognitive tests. We need better markers and indicators and tests telling us which women may be having difficulty."

Women who were older and had less education also had more executive-function problems.

There are several hypotheses as to why chemotherapy might cause these problems. One is that chemotherapy is toxic to neurological stem cells; another is that chemotherapy increases the amount of inflammation in the body, which then gets into the brain, and chemotherapy also causes DNA damage.

Hormonal therapies can also affect cognitive function and although the authors took this into account, individual variations in estrogen levels may have influenced the results, the authors noted.

"People sometimes think women are exaggerating [chemo brain] but this study showed that self-reported impairment actually correlates with brain impairment pointing to the fact that they should not be ignored," Kesler said.

Although the new study showed an association between brain function and chemotherapy, it did not prove a cause-and-effect relationship.

More Information

The American Cancer Society has more on chemo brain.