Chemotherapy linked to lasting brain change
November 06, 2006
By Roxanne Khamsi
|The baseline level of brain activity (indicated by yellow and orange) in the frontal cortex is higher in patients who have not undergone chemotherapy (Image: Dan Silverman, UCLA)
The side effects of chemotherapy linger in the brain for at least a decade following treatment – it may explain why many patients complain of cognitive difficulties years later, new research suggests.
The study on breast cancer patients pinpoints changes in brain metabolism that might account for patients’ memory problems and difficulty in doing more than one thing at a time.
Chemotherapy involves powerful chemical compounds which prevent cancer from spreading or slows its process. But a quarter of patients complain of “chemo brain” – a condition that describes a sense of reduced mental capacities, or lack of focus. One recent study suggests as many as 82% of patients are affected.
The effects are relatively subtle, says Daniel Silverman at the David Geffen School of Medicine at the University of California, Los Angeles, US. “People are not going from an IQ of 120 to 80.” But the changes are real, he adds: “Typically you’ll see a patient who says ‘I can’t multitask like I used to’.”
Silverman and colleagues recruited 21 women who had undergone surgery to remove breast cancer, 16 of whom had received chemotherapy for the disease five to 10 years before the study.
Subjects completed tasks that tested their short-term memory as a machine recorded blood flow to regions of their brain, using a scanning technique known as positron emission tomography (PET scanning). Greater blood flow to a region indicates a higher rate of metabolism – more activity – in those brain cells.
Researchers compared the brain activity of these participants to that of 13 healthy controls. Patients who had received chemotherapy had reduced rates of metabolism in specific regions of the frontal cortex – an area involved in memory recall – compared to the controls.
The women whose scans revealed more abnormalities in brain metabolism, were the ones that preformed worst in the short-term memory test, the researchers found.
The toxic effects of the cancer treatment – either directly or indirectly – damages brain cells and reduces their function, Silverman says.
He suggests that closer monitoring of patiwents’ brain response to chemotherapy could allow doctors to adjust treatment to avoid causing “chemo brain”.
Original source: http://www.newscientist.com