Every year millions of Americans undergo chemotherapy. The goal of the treatment is to destroy cancer, but along the way more than half of the people treated lose something else. They suffer from something called “chemo brain” which causes problems with thinking and memory. In some cases it can be temporary, lasting a few months. In others it can last years.
New findings
Now a CIRM-funded study by researchers at Stanford has found what may be behind chemo brain and identifying potential treatments.
In an article on the Stanford Medicine News Center, senior author Michelle Monje said:
“Cognitive dysfunction after cancer therapy is a real and recognized syndrome. In addition to existing symptomatic therapies — which many patients don’t know about — we are now homing in on potential interventions to promote normalization of the disorders induced by cancer drugs. There’s real hope that we can intervene, induce regeneration and prevent damage in the brain.”
Exposure to chemotherapy
The team examined postmortem brains of children who had received chemotherapy and those who had not. Chemotherapy‑treated brains showed far fewer oligodendrocytes, the cells that protect nerve fibers.
Next, the team injected methotrexate into mice and compared their brains with untreated mice several weeks later. Treated mice had fewer oligodendrocytes, and the remaining cells were immature, indicating that the drug blocked their development.
These internal changes showed up in behavior. Treated mice moved more slowly, showed higher anxiety, and had impaired memory — symptoms that lasted up to six months.
The researchers also found that chemotherapy disrupted other brain cells, triggering a cascade that worsened memory and other cognitive functions.
The study, published in Cell, offered some hopeful results. When researchers gave treated mice a drug designed to counter methotrexate’s side effects, their cognitive problems eased.
Monje says this is the direction her research will continue.
“If we understand the cellular and molecular mechanisms behind cognitive dysfunction after cancer therapy, we can develop effective treatments. It’s an exciting moment.”
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