Source: NPR Date: December 28, 2012 Author:  Patti Neighmond   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 [...]