Cancer patients have long complained about a “mental fog” after treatment — and now, two City of Hope studies involving hematopoietic cell transplantation patients verify that these cognition problems can be real.

Researchers delivered both studies as podium presentations during the American Society of Hematology meeting in New Orleans in December 2009.

Lennie Wong, left, Smita Bhatia and Alysia Bosworth (Photo by p.cunningham)

Department of Population Sciences researchers used two different methods to measure impairments such as memory loss and concentration problems in transplant patients. These patients undergo conditioning treatments like total body irradiation and take drugs to prevent graft-versus-host disease.

The scientists found that up to two out of five hematopoietic cell transplant patients reported problems with concentration and memory.

City of Hope researchers tackled the issue because scientific evidence on cognition problems is unclear, said Smita Bhatia, M.D., M.P.H., director of the Center for Cancer Survivorship, chair of the Department of Population Sciences, and senior author on both studies.

“Some of the studies that had used structured neuropsychological tests indicated minimal problems, while others indicated significant issues with memory and attention,” said Bhatia. “In the meantime, patients were indicating problems with attention and difficulty getting back to work.

“To address these issues, we decided to mount a large-scale comprehensive study. Thus far, about 400 patients have been studied.”

In the first study, lead author Lennie Wong, Ph.D., associate research professor, used standardized tests to detect cognitive impairments. In a companion study, lead author Alysia Bosworth, clinical research assistant, used a questionnaire asking patients to report their problems with concentration, memory and multitasking.

In the three-year study using the objective exam — one of the longest studies of its kind — patients were tested before transplantation, and then six months and one, two and three years later. The test assessed attention, memory, multitasking and other aspects of thinking, as well as intelligence quotient.

These objective tests, which were originally been designed to diagnose impairments in individuals with significant neurologic problems due to traumatic brain injury or dementia, showed cognitive impairments in fewer than 10 percent of hematopoietic cell transplant patients.

However, in the companion study, up to 40 percent of patients reported problems with concentration and memory. Researchers believe objective tests may not be capable of capturing neuropsychological impairments experienced by transplant patients, accounting for the disparity between results of the two assessment methods.

“The transplant population is having more subtle problems, and these objective tests may not be the most sensitive tests for picking up those problems they’re having,” said Bhatia.

Regardless of the method used to assess neurocognitive impairment, it was clear that people with the impairments had difficulty returning to work.

Bhatia believes health care providers need to understand patients’ concerns about cognitive problems and steer them toward support from neuropsychologists and other psychosocial services. Patients may need practical strategies to cope with these impairments.

Both studies followed patients who received allogeneic transplants (blood stem cells from a healthy donor) or autologous transplants, which use a patient’s own, purified blood stem cells. Allogeneic transplant patients struggled more than autologous transplant patients, particularly with memory loss, information processing and “executive functioning” (the ability to multitask).

Researchers will continue administering both objective and subjective tests to give a more complete picture of what patients are experiencing.

Meanwhile, “targeted surveillance and early intervention may facilitate patients’ smooth reintegration into society,” Wong said.

Other contributors to the studies included population sciences researchers Rose Danao, Doojduen Villaluna, M.S., Sunita Patel, Ph.D., Mitzi Gonzalez and Marcia Grant, R.N., D.N.Sc., as well as Stephen J. Forman, M.D., chair of the Department of Hematology & Hematopoietic Cell Transplantation and Francis and Kathleen McNamara Distinguished Chair in Hematology and Hematopoietic Cell Transplantation.