Impaired Thinking After Stem Cell Therapy Temporary

A type of stem cell therapy called myeloablative hematopoietic cell transplantation (HCT) is known to cause though, or “cognitive,” impairments, but new research suggests that much of this impairment is temporary.

As reported in the medical journal Blood, Dr. Karen Syrjala, from the Fred Hutchinson Cancer Research Center in Seattle, and colleagues assessed cognitive ability in 142 adult patients who underwent HCT for various cancers. Standard tests were used to assess brain function before HCT, 80 days after HCT, and again one year later. Compared with the pre-HCT results, all of the tests showed a decline in cognition at 80 days. However, by one year, the scores had largely returned to their pre-treatment levels. In contrast, strength and dexterity test scores remained low. Factors that predicted an improvement in cognitive ability included receiving no chemotherapy or just hydroxyurea chemotherapy before the procedure and not receiving medications for graft-versus-host disease, a condition in which the body mounts an autoimmune response against the transplanted cells. Although short-term cognitive problems after HCT can be severe, most patients return to their pre-transplantation levels of brain function by one year after the procedure, the researchers conclude. However, they suggest that brain “function should be evaluated in patients who continue to have cognitive complaints after one year.” (Source: Blood: Reuters Health: November 2004.)