Chemo's Effect on Cognition is Debated

New research suggests mental impairment may be present before the therapy

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HealthDay Reporter

MONDAY, June 21, 2004 (HealthDayNews) -- Women undergoing chemotherapy for breast cancer have been widely reported to suffer from "chemobrain," or problems with focus, concentration and memory.

But researchers reporting in the June 21 issue of the journal Cancer suggest that the incidence of chemobrain may be exaggerated.

Previous research didn't take into account cognitive deficits before chemotherapy started, the study authors state. In addition, those older studies compared a patient's intellectual function after chemotherapy to standards for women of similar age and education, instead of the patient's own cognitive ability before therapy.

"The existence of chemobrain is indeed somewhat controversial," agreed Dr. Carl Kardinal, head of the Ochsner Cancer Institute in New Orleans.

Which is not to say chemobrain doesn't exist. It's just that it may not always be due to chemotherapy.

"Chemotherapy can cause declines, there's no question about that. But some people have cognitive impairments due to their cancer which are present before treatment starts," said Christina A. Meyers, senior author of the study and professor of neuropsychology at the University of Texas M.D. Anderson Cancer Center in Houston.

"Some of the people [previous researchers] called 'decliners' may have been impaired beforehand and some who were functioning normally may have in fact declined. They were missing people on both ends," she said.

"Cancer patients are vulnerable to adverse symptoms that can be caused by disease," Meyers added. "Some have said they had fatigue and distractibility problems before diagnosis, which they attributed to overwork or what have you, and which, in retrospect, probably heralded their diagnosis."

In their study, Meyers and her colleagues were the first to evaluate cognitive skills before chemotherapy as well as after. The researchers conducted comprehensive neuropsychologic evaluations of 84 women with noninvasive breast cancer before they started chemotherapy.

During this pre-chemotherapy period, 36 percent already exhibited evidence of cognitive impairment, namely problems with verbal skills and memory function. To a lesser extent, the women also had problems with nonverbal memory, psychomotor processing speed and attention, visual tasks and some fine motor skills.

So given the fact that nearly a third of the women were showing signs of impairment before the start of chemotherapy, it may be inaccurate to blame the therapy itself for cognitive problems, the researchers said.

Not all experts agree with the new research's conclusions, however.

The critics include Dr. Stewart Fleishman, director of cancer supportive services at Continuum Cancer Centers of New York, Beth Israel Medical Center and St. Luke's-Roosevelt Hospital Center in New York City, who has been involved in a large study of chemobrain.

"They [the study authors] didn't take people with a blank slate, [they only took] people who already had breast cancer. It's much more complicated," Fleishman said, adding that any number of factors, including hormones, could be causing the cognitive changes.

Either way, Meyers said, the new research still only reveals what happens, not why. "Where [chemobrain] comes from is the uncertain part," she said. "What we've just established is that it occurs. The next step is who does it happen to and why."

Depending on what that "why" turns out to be, there could be a number of treatments, Meyers said.

"If it's an inflammatory response, then we would go after immune activity," she said. "If it's genetic susceptibility, we might screen people for that and then be very proactive with them about treating symptoms before they start."

Other treatment options include various medications, behavioral interventions, and compensatory strategies, such as learning how to organize yourself, self-hypnosis and exercise. "There are lots and lots of things we can do to attenuate symptoms and make them more manageable," Meyers said.

The main thing is not to deny that chemobrain exists, she said.

"It's real, it happens and it should be treated as aggressively as the cancer is being treated," Meyers said. "Physicians should be aware that if someone is offering complaints in this area, they should be referred because there are things to be done."

More information

The American Cancer Society has more on chemotherapy for breast cancer.

SOURCES: Christina A. Meyers, Ph.D., professor of neuropsychology, the University of Texas M.D. Anderson Cancer Center, Houston; Stewart Fleishman, M.D., director, cancer supportive services, Continuum Cancer Centers of New York, Beth Israel Medical Center and St. Luke's-Roosevelt Hospital Center, New York City; Carl Kardinal, M.D., head, Ochsner Cancer Institute, New Orleans; June 21, 2004, Cancer

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