According to new research, Chemotherapy can induce changes in patient brains, affecting their concentration and memory. Dubbed “chemo brain,” the physiological effects were detected by researchers using PET/CT scans.

“The chemo brain phenomenon is described as ‘mental fog’ and ‘loss of coping skills’ by patients who receive chemotherapy,” said Dr. Rachel Lagos, a diagnostic radiology resident at the West Virginia University School of Medicine. “Because this is such a common patient complaint, healthcare providers have generically referred to its occurrence as ‘chemo brain’ for more than two decades.”

“Chemo brain” may be common, but it’s cause has eluded doctors for as long as it’s been around. Previous studies using MRIs found small changes in brain volume following chemotherapy, but no definite link was established. Lagos and his colleagues looked at changes to the brain’s metabolism instead of volume.

“When we looked at the results, we were surprised at how obvious the changes were,” said Lagos. “Chemo brain phenomenon is more than a feeling. It is not depression. It is a change in brain function observable on PET/CT brain imaging.”

The researchers looked at PET/CT brain images from 128 patients who had chemotherapy treatment for breast cancer. The results, obtained using software that reveals differences in brain metabolism, found statistically significant differences decreases in regional brain metabolism closely related to symptoms of “chemo brain.”

“The study shows that there are specific areas of the brain that use less energy following chemotherapy,” said Lagos. “These brain areas are the ones known to be responsible for planning and prioritizing.”