Most Recover from 'Chemo-Brain' by 5 Years after Stem Cell Transplant


‘Chemo-brain’ is experienced by many patients who undergo bone marrow or blood stem cell transplantation to treat blood cancers as well as a decline in fine motor skills due to the toll of their treatment.

According to a new study published in the May 2, 2011 online edition of the Journal of Clinical Oncology these effects are largely temporary with most patients returning to normal motor and memory function within five years.

Chemo brain is a common term used by cancer survivors to describe thinking and memory problems that can occur during and after cancer treatment. Chemo brain is also be called chemo fog or “mild cognitive impairment." Most define it as being unable to remember certain things and having trouble finishing tasks or learning new skills.

Hematopoietic transplantation (HCT) involves bone marrow or stem cell transplantation. The chemotherapy drugs that leukemia and lymphoma patients receive prior to HCT along with the medicines used to combat graft-versus-host disease can impact motor and memory skills.

Karen Syrjala, Ph.D., director of Biobehavioral Sciences at the Fred Hutchinson Cancer Research Center, designed their prospective study to determine whether patients recover from these neurocognitive deficits within five years of transplant.

For the study, Syrjala and colleagues identified 92 patients who received allogeneic HCT for chronic myeloid leukemia, acute leukemia, lymphoma or myelodysplastic syndrome. Allogeneic means the donor cells come from a matched donor and not the patient.

The case-matched controls (n = 66) group was composed of individuals the patients were asked to nominate, such as a sibling or friend of the same gender and similar age who had neither received a transplant nor were in active cancer treatment.

Both groups completed standardized neuropsychological tests including information processing speed (Trail Making A and Digit Symbol Substitution Test), verbal memory (Hopkins Verbal Learning Test–Revised), executive function (Controlled Oral Word Association Test and Trail Making B), and motor dexterity and speed (Grooved Pegboard).


Survivors were retested after 80 days and 1 and 5 years after transplantation. Case-matched controls (n = 66) received testing at the 5-year time point.

Analysis of the tests results showed that most patients made substantial improvements in neurocognitive function over the five years after their transplant.

Survivors recovered significant cognitive function from post-transplantation (80 days) to 5 years in all tests (P .06). Between 1 and 5 years, verbal fluency improved, as did executive function.

Motor dexterity did not, remaining below controls and more than 0.5 standard deviation below population norms.

Syrjala and colleagues wrote, "However, contrary to expectations, neither motor dexterity nor verbal learning and retention improved between one and five years. Deficits were most notable in motor speed and dexterity."

A Global Deficit Score (GDS) summarized overall impairment. This mostly mild neurocognitive dysfunction remained at five years for twice as many long-term survivors (41.5 %) versus controls (19.7 %).

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 chemotherapy may contribute.

"The major clinical implication of this research is to assure HCT recipients and their health care providers that further progress will occur in their information processing capacity between one and five years after treatment," the authors wrote. "However, it is equally important to validate for long-term survivors that not all HCT recipients fully recover neurocognitive function by five years. These results provide further indication of the need for cognitive rehabilitation strategies after one year for those residual deficits."

Prospective Neurocognitive Function Over 5 Years After Allogeneic Hematopoietic Cell Transplantation for Cancer Survivors Compared With Matched Controls at 5 Years; Karen L. Syrjala, Samantha B. Artherholt, Brenda F. Kurland, Shelby L. Langer, Sari Roth-Roemer, JoAnn Broeckel Elrod, and Sureyya Dikmen; JCO May 2, 2011:; published online on May 2, 2011; DOI:10.1200/JCO.2010.33.9119

American Cancer Society: Chemo-Brain