Chemo Brain is Real and Affects Ability to Concentrate

The ability to focus and maintain concentration seems to be directly affected in "chemo brain."

Those undergoing chemotherapy may find some solace after researchers from the University of British Columbia (UBC) confirmed that “chemo brain” is a very real thing.

The negative cognitive effects of cancer treatment have long been suspected, but new research confirms that patients with the symptom lack the ability to sustain focused thought, with their brain remaining in a disengaged state for long periods of time.

“A healthy brain spends some time wandering and some time engaged,” Todd Handy, a professor of psychology at UBC, said in a press release. “We found that chemo brain is a chronically wandering brain, they’re essentially stuck in a shut out mode.”

The researchers compared performance of 19 breast cancer survivors who self-reported cognitive problems to 12 healthy controls on a target detection task using electroencephalogram. The participants were periodically asked to report their attentional state.

After an average of 38 trial blocks, the cancer survivors reported significantly higher levels of mind wandering (M = 57%, SD = 16%) compared to healthy controls (= 39%, SD = 15%; t(29) = −2.93, p = .007). Cancer survivors responded slower than controls, however this did not reach statistical significance. Parietal (P3) event-related potential component elicited by visual targets during the task was smaller in cancer survivors than controls, and cancer survivor also showed greater neural activity at rest.

With the effects of chemotherapy on patients observed at least three years after treatment, the study results recognize the persistent effects that treatment can have on patients and their quality of life.

Using electroencephalogram and target detection tasks to detect cognitive deficits in cancer survivors may be useful, as tests developed to detect cognitive deficits in people with Alzheimer’s or Parkinson’s have been shown to not be sensitive enough to detect changes in cancer survivors. 


  1. Kam JWY et al. Clin Neurophysiol. 2015; doi:10.1016/j.clinph.2015.03.007. 
  2. University of British Columbia press release