It's well-known that chemotherapy often comes with side effects like fatigue, hair loss and extreme nausea. What's less well-known is how the cancer treatment affects crucial brain functions, like speech and cognition.
For Yolanda Hunter, a 41-year-old hospice nurse, mother of three and breast cancer patient, these cognitive side effects of chemotherapy were hard to miss.
"I could think of words I wanted to say," Hunter says. "I knew what I wanted to say. ... There was a disconnect from my brain to my mouth."
Before getting treated for cancer, Hunter led a busy, active lifestyle. But the effects of chemotherapy on her brain made it difficult for her to do even the most basic things.
"I couldn't even formulate a smile. I had no expression," she says. "I might feel things on the inside, but it didn't translate to the outside. ... It literally felt like you were trying to fight your way through fog."
Some cancer patients call this mental fog "chemo brain." And now researchers are trying to quantify exactly what chemo brain really is.
Oncologist Jame Abraham, a professor at West Virginia University, says about a quarter of patients undergoing chemotherapy have trouble processing numbers, using short-term memory and focusing their attention.
Using positron emission tomography, or PET, scans to measure blood flow and brain activity, Abraham looked at the brains of 128 breast cancer patients before they started chemotherapy and then again, six months later.
On the second brain scan, he found significant decreases in brain activity in regions responsible for memory, attention, planning and prioritizing. Those results were recently presented at the Radiological Society of North America meeting.
Chemotherapy "can cause damage to bone marrow, hair cells, mucosa," Abraham says. "In the same way, it can potentially cause changes in the brain cells, too."
But Max Wintermark, a brain imaging specialist at the University of Virginia, says the findings bring up more questions than answers: Do brain changes occur with all types of chemotherapy or just one type? Do they only happen to breast cancer patients or to all cancer patients?
Wintermark says these are critical questions that warrant further study.
In the meantime, Wintermark says there are some simple ways cancer patients can work around "chemo brain": reminders on sticky notes and detailed grocery lists.
And fortunately, Abraham says chemo brain is almost always temporary. He says patients usually regain their full cognitive abilities within a year or two after chemotherapy treatment ends.