Chemobrain: Most patients recover within five years

Many patients who undergo bone marrow or blood stem cell transplantation experience chemobrain, declines in mental and fine motor skills due to the toll of their disease and its treatment.

A new study led by Hutchinson Center researchers published online May 2 in the Journal of Clinical Oncology, found that overall, these effects are largely temporary and that most patients can expect a return to normal motor and memory function within five years. However, the study also found that deficits in fine motor skills and verbal memory remained longer for a significant percentage of patients and warrant more attention by health care providers.

Testing neurocognitive impairment

It has been widely documented that powerful chemotherapy drugs that cancer patients receive prior to transplantation—as well as medicines to combat graft-vs.-host disease—can impact motor and memory skills. The new study, led by the Clinical Research Division’s Dr. Karen Syrjala, director of Biobehavioral Sciences and co-director of the Survivorship Program, looked at whether patients recover from these neurocognitive deficits within five years of transplant.

For the study, Syrjala and Clinical Research colleagues Drs. Samantha Artherholt, Brenda Kurland, and Shelby Langer identified 92 patients who had received an allogeneic (cells from a donor) bone marrow or stem cell transplants. Each patient was matched with a healthy control subject.
 
The tests included immediate and delayed recall of a list of words, saying out loud as many words as possible that begin with specific letters, the ability to sequentially link letters and numbers on paper, learning to match numbers and symbols and write the symbols on paper to match random numbers, and putting toothpick-sized pegs into holes as fast as possible.

Surprising rates of continued impairment

Analysis of the tests results showed that most patients made substantial improvements in neurocognitive function over the five years post-transplant. “However, contrary to expectations, neither motor dexterity nor verbal learning and retention improved between one and five years,” the authors wrote. “Deficits were most notable in motor speed and dexterity.”

Described as mostly mild, the neurocognitive dysfunctions remained at five years for twice as many long-term survivors (41.5 percent) versus controls (19.7 percent).

Syrjala said the evidence of continued impairment surprised the researchers. “We really thought the rates would be lower,” she said. “We were thrilled to see that people recovered substantially, but we also were surprised that so many people did continue to have measurable deficits in some areas even after five years.”

Syrjala said the reasons for persistent deficits are unknown and more research is needed to examine the causes. One theory is that some cancers, especially leukemia and lymphoma, are “whole-body” cancers because blood circulates throughout the body and these diseases may cause their own neurocognitive impacts, in addition to what chemotherapies may contribute.

Need for cognitive rehabilitation strategies

The researchers hope their findings will both assure patients and their health care providers that information processing will progress over time and validate the reality of such declines for some long-term survivors. “These results provide further indication of the need for cognitive rehabilitation strategies after one year for those residual deficits,” the authors wrote.

The investigation is the first to prospectively follow the same group of patients for five years for any cancer, according to the authors. The study builds upon previous findings by Syrjala and colleagues, published in 2004, which followed the same group of patients to one year after transplant. That study also found that neurocognitive impacts of transplantation are largely temporary.

Co-authors on the paper included researchers from the University of Washington School of Medicine and School of Social Work and Arizona Medical Psychology. The National Cancer Institute funded the research.