Few people have a greater need for clarity of mind than cancer patients, who must focus their energy and thoughts on healing. Yet many have complained about a “mental fog” that sets in after treatment. The reality of these cognitive impairments remains shrouded in uncertainty.

Now, two studies verify that these hitches that cloud patients’ minds can be real.

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

Researchers in City of Hope’s Department of Population Sciences looked at patients who had received bone marrow transplants or other forms of hematopoietic cell transplantation. The studies used two different methods to measure impairments such as memory loss and concentration problems.

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

City of Hope researchers tackled the issue because scientific evidence on these types of 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.

Previous studies on the issue showed conflicting results, according to Bhatia. “In the meantime, patients were indicating problems with attention and difficulty getting back to work,” she said.

To address these issues, her team has taken a large-scale, comprehensive approach, so far studying 400 patients.

In the first study, lead author Lennie Wong, Ph.D., associate research professor, used standardized tests to detect mental-skill impairments.

The study — one of the longest of its kind — tested patients before transplantation and several times over a three-year period after. The tests checked attention, memory, multitasking and other aspects of thinking, as well as intelligence quotient.

These objective tests showed mental impairments in fewer than 10 percent of patients.

In a companion study, lead author Alysia Bosworth, clinical research assistant, asked patients to complete a questionnaire reporting their problems with concentration, memory and multitasking.

This study found that up to 40 percent of patients reported problems with concentration and memory.

The researchers believe the objective tests in the first study may not be able to capture mental impairments experienced by transplant patients. This would account for the differences between results of the two study 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,” Bhatia said.

Regardless of the testing method, both studies showed clearly 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.

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