The women performed a card-sorting task designed to measure problem-solving skills and also reported their own perception of their cognitive abilities.
Women with breast cancer, whether or not they had had chemotherapy, showed reduced activity in two areas of the prefrontal cortex, including one heavily involved in memory, the investigators found.
"The non-chemo group did show some brain changes but their actual performance of cognitive tasks was not impaired," said Kesler, who is an assistant professor of psychiatry and behavioral sciences at Stanford University School of Medicine. "For women who had chemo, their deficit, their brain change is more severe to the point where they are showing actual performance impairment on cognitive tests."
The group that had undergone chemotherapy also had reduced activity in the prefrontal cortex and tended to repeat errors and complete tasks more slowly compared to both other groups.
This reduced activity also correlated with how patients viewed their own abilities.
The worse the disease and the worse the women perceived their own functioning, the lower the activity.
"The pattern of brain activation actually matched up with self-report," said Janelsins. "That's important because a lot of times self-report measures aren't matching up with performance on some cognitive tests. We need better markers and indicators and tests telling us which women may be having difficulty."
Women who were older and had less education also had more executive-function problems.
There are several hypotheses as to why chemotherapy might cause these problems. One is that chemotherapy is toxic to neurological stem cells; another is that chemotherapy increases the amount of inflammation in the body, which then gets into the brain, and chemotherapy also causes DNA damage.
Hormonal therapies can also a
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