Two new studies are reviving debate over the causes of "chemo brain," a mental fog that affects up to 75% of cancer survivors.
Cancer patients for decades have complained of feeling forgetful or
mentally fuzzy, with many blaming toxic chemotherapy regimens. While
the problem feels very real to patients, some doctors have dismissed the
issue as imaginary.
Now, new research shows evidence of mental fog in women's brain scans.
A study presented last week at a meeting of the Radiological Society
of North America found that chemo can cause brain changes that affect
memory and concentration.
Researchers studied 128 breast
cancer patients who complained of chemo brain, scanning their brains
both before and after treatment, according to the study, presented by
Rachel Lagos, a radiology resident at the West Virginia University
School of Medicine.
Researchers used tests called PET/CT
scans, or positron emission tomography, which captures brain activity by
measuring how quickly it uses energy. CT scans, or computed tomography,
use multiple X-rays to provide detailed pictures.
Lagos and
her colleagues found declines in brain activity in areas involved with
long-term memory, as well as problem solving, organizing and
prioritizing. "Every single person showed change," Lagos says.
About 20% of cancer survivors complain of persistent memory problems,
long after treatment ends, according to the National Cancer Institute.
Patients with demanding professional jobs are more likely than others to
complain of memory problems.
Scientists so far don't know for sure what might cause these symptoms.
Doctors such as Patricia Ganz, of UCLA's Jonsson Comprehensive
Cancer Center, are studying the role of inflammation both in chemo brain
and cancer-related fatigue. Her research has found that many women who
complain of mental fog also suffer fatigue, depression and sleep
problems.
A study by Tim Ahles, of New York's Memorial
Sloan-Kettering Cancer Center, suggested that women may be more
susceptible to chemo brain if they carry a form of a gene linked to
Alzheimer's disease. It's also possible that memory problems and cancer
have common risk factors, giving patients a greater chance of both.
Reaction to Lagos' study among breast cancers survivors has been
dramatic. She received 800 e-mails from cancer survivors within a day of
presenting her findings. Many were relieved that a doctor had confirmed
their symptoms were real, Lagos says.
"People I'd never met
where sharing their experiences. It was heartbreaking," Lagos says. For
patients, being told that their symptoms aren't real "can be even worse
than getting the diagnosis in the first place, because people think,
'Oh, I'm crazy.'"
A small study presented today at the annual
San Antonio Breast Cancer Symposium, however, suggests that chemo may
not be to blame for the women's memory impairments.
That's
because women who complained of chemo brain had lower scores on memory
tests even before treatment, says researcher Bernadine Cimprich, of the
University of Michigan School of Nursing. Her study of 99 people used
functional MRIs, or magnetic resonance imaging. Women diagnosed with
cancer scored worse than healthy women in a comparison group, both
before and after patients' treatment.
Her findings are
consistent with earlier studies, which have found that 20% to 30% of
patients have lower-than-expected scores, even before chemo.
Women who underwent chemo reported more fatigue than other women, even
before receiving the drugs, Cimprich say. The more exhausted women
felt, the worse their scores.
That suggests that at least some
of the women's memory problems could have been caused by the stress and
sleeplessness of being diagnosed with cancer, Cimprich says.
Studies show that other cancer therapies, such as a hormonal drug called
tamoxifen, also can cause fatigue, according to the NCI.
Early menopause, which can be caused by chemotherapy or surgery to
remove the ovaries, also can cause memory problems, says oncologist
Claudine Isaacs, of Georgetown's Lombardi Comprehensive Cancer Center.
Hot flashes caused by medications or early menopause can make women lose
sleep, affecting their memory.
Cancer centers might be able
to relieve women's symptoms by offering more psychological support,
Cimprich says, as well as cognitive behavior therapy and mindfulness
activities, which can include meditation. Exercise also has been shown
to relieve fatigue and give people more energy.
Lagos says
women can also cope with their mental fog by making lists and plans. For
example, women in an earlier study felt overwhelmed by the task of
organizing and cooking a meal.
But the same women were able to
function much better after researchers gave them written menus, which
helped the women focus their grocery shopping and meal preparation,
Lagos say.
"It's critically important to understand the side
effects of therapy and minimize them," Isaacs says. "We don't want women
to say no to very important therapy because of this."
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