Memory Research News in Problems

Chemo-brain: prevalence, why it happens, and how to help

  • The largest study to date of chemo-brain shows that 45% of women with breast cancer report it's a substantial problem for months after chemotherapy.
  • A rat study suggests an effect of chemotherapy on dopamine and serotonin may be partly responsible.
  • Better cognitive function, and improved mood, are linked to frequent moderate-to-vigorous physical exercise among breast cancer survivors.
  • A new cognitive-behavioral treatment program has been trialed with positive results.
Chemo-brain common among women with breast cancer

A study involving 581 breast cancer patients and 364 healthy age-matched people (mean age 53) has found that women with breast cancer reported significantly greater cognitive difficulties for up to six months after chemotherapy. Cognitive difficulties were evaluated using FACT-Cog, an assessment that examines a person's own perceived impairment as well as cognitive impairment perceived by others.

Compared to healthy controls, the FACT-Cog scores of women with breast cancer were 45% lower at outset. This difference increased substantially after chemotherapy (see graph). The first assessment after chemotherapy was at 4.8 months, with the second 6 months after that (i.e, nearly a year after chemotherapy). Patients were also much more likely to report significant cognitive decline from diagnosis to the first post-chemotherapy assessment (45.2% vs 10.4% of the controls), and from prechemotherapy to second post-chemotherapy assessment (36.5% v 13.6%).

Having more anxiety and depressive symptoms at the outset, and having lower cognitive reserve (assessed by a reading score), were significantly associated with lower scores.

Those who received hormone therapy and/or radiation treatment after chemotherapy had similar cognitive problems to women who received chemotherapy alone.

Chemobrain a product of dysfunction in dopamine & serotonin release?

A rat study suggests one reason for chemo-brain is an effect of chemotherapy on the neurotransmitters dopamine and serotonin. Both of these are important for both mood and cognition.

After giving carboplatin (commonly used with breast, bladder, colon and other cancers) to rats over four weeks, researchers found that the release and uptake of both dopamine and serotonin in their brains became impaired, although overall levels didn’t change. The rats also showed impaired cognition.

Exercise helps memory for breast cancer survivors

A role for dopamine and serotonin in chemo-brain is consistent with findings that anxiety and depression are risk factors for chemo-brain. No surprise then, that a study has found that physical exercise helps improve cognition in breast cancer survivors.

The study used self-reported data from 1,477 breast cancer survivors, as well as from accelerometers worn by 362 of the women. It found that breast cancer survivors who did more moderate or vigorous physical activity (including brisk walking, biking, jogging, or an exercise class) had fewer subjective memory problems.

Higher levels of physical activity were associated with lower levels of fatigue and distress, and higher levels of physical confidence. The researchers suggest that exercise reduces subjective memory problems via these factors.

Cognitive-behavioral therapy may help

A cognitive-behavioral therapy called "Memory and Attention Adaptation Training" (MAAT), which helps cancer survivors to increase their awareness of situations where memory problems can arise and to develop skills to either prevent memory failure or to compensate for memory dysfunction, has been trialed in a small randomized study involving 47 Caucasian breast cancer survivors. The patients were an average of four years post-chemotherapy.

The participants were either assigned to eight visits of MAAT (30 to 45 minutes each visit) or supportive talk therapy for the same length of time. Both treatments were delivered over a videoconference network between health centers.

MAAT participants reported significantly fewer memory problems as well as improved processing speed two months after treatment. They also reported much less anxiety about cognitive problems.


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