Many Patients with “Chemo Brain” Recover within Five Years

A study of “chemo brain”—the foggy thinking and forgetfulness that patients may experience after chemotherapy—suggests that the condition improves substantially over time for a majority of patients. For some patients, however, symptoms may persist for more than five years after treatment. These findings were recently reported in the Journal of Clinical Oncology.

Chemo brain refers to changes in cognitive function, such as loss of memory and inability to think clearly or perform some daily functions. Researchers have not been able to pinpoint the cause of chemo brain, but current studies are evaluating brain structure and function in order to better understand the effects of chemotherapy on the brain.

To understand more about how chemo brain affects patients several years after treatment, researchers evaluated 92 patients at the Fred Hutchinson Cancer Research Center in Seattle. Patients had been treated for blood cancers with chemotherapy and bone marrow or stem cell transplants. The patients were matched with controls who had not undergone cancer treatment.

Standardized tests were used to assess cognitive function among all participants. The test measured cognitive functions including memory and motor skills. Findings were combined to create a Global Deficit Score (GDS), which summarized overall impairment. Results from patients were compared with results from controls.

  • During the five years following treatment, survivors were able to recover much of their cognitive function. Verbal recall (the ability to call up a known word—one that is on the “tip of the tongue”), however, was more difficult to recover than other functions.
  • Some functions, such as verbal fluency and executive function (including abilities such as planning and organizing) improved during the five years post-treatment, whereas motor skills did not improve during this time.
  • At five years after treatment, GDS indicated that 41.5% of survivors had deficits that were mild or greater compared with 19.7% of controls.

Though it appears that the cognitive impairment following chemotherapy known as chemo brain is largely temporary and likely to improve during the five years following treatment, difficulties persist for a significant number of survivors (more than 40%). An understanding of the risk factors and reasons for these lasting impairments is needed, as are improved methods to rehabilitate cognitive function.

Reference: Syrjala KL, Artherholt SB, Kurland BF, et al. Prospective neurocognitive function over 5 years after allogeneic hematopoietic cell transplantation for cancer survivors compared with matched controls at 5 years. The Journal of Clinical Oncology [early online publication]. May 2, 2011.

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