FRIDAY, May 6 (HealthDay News) -- A decline in memory and fine-motor skills is common among patients who undergo a bone marrow or stem cell transplant to treat leukemia or lymphoma, but most patients return to normal within five years, according to a new study.

Previous research has shown that the chemotherapy drugs these patients take before transplantation and medicines they take to prevent rejection of the transplanted cells can affect memory and motor skills. This study looked at how long it takes them to recover from those problems, often referred to as "chemo brain."

The study included 92 patients with chronic myeloid leukemia, acute leukemia, lymphoma or myelodysplastic syndrome, in which the bone marrow does not function normally. The patients had received an allogeneic (cells donated by another person) bone marrow or stem cell transplant.

After treatment, the patients' memory and motor skills were assessed. Most patients showed substantial improvement in neurocognitive function between one and five years after their transplant.

But deficits, described as mostly mild, persisted for five years in nearly 42 percent of the patients, a finding that surprised the researchers at the Fred Hutchinson Cancer Research Center in Seattle.

"We really thought the rates would be lower," study leader Karen Syrjala, director of Biobehavioral Sciences, said in a Hutchinson news release. "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."

Further research is needed to identify the reasons for these persistent deficits, she added.

The study was published May 2 online in the Journal of Clinical Oncology.

More information

The U.S. National Heart, Lung, and Blood Institute has more about bone marrow and stem cell transplant.