Chemo Fog or Chemo Brain – Does It Really Ever Go Away?

“Chemo fog” or “chemo brain” is a neurological side effect of chemotherapy manifested as reduced brain function, or more specifically decreased executive brain function, that is experienced by patients who have or who are undergoing chemotherapy.

In the recently held  Cure Panel Talk Show’s episode on Breast Cancer, we discussed side effects and toxicity related to chemotherapy with Dr. Rugo and Dr. Schattner. Dr. Hope Rugo is a hematologist and oncologist specializing in breast cancer treatment. Dr. Elaine Schattner is a medical educator, non-practicing oncologist and a breast cancer survivor. She is a Clinical Associate Professor of Medicine at Weill Cornell Medical College in New York.

Along with dealing with the shock of newly diagnosed cancer, they have to deal with a greater dilemma of getting chemotherapy for increased survival on one hand, and at the same time having to suffer the extreme side effects of chemo, which may change your lives completely.

One such side effect is chemo brain, where patients have hard time thinking normally and experience kind of things noticed in old people. Chemo brain is a burning issue with cancer patients – before, during, and after chemotherapy.

It manifests as impaired executive brain function like disturbed short term memory where they have name finding problems – they forget people’s names, forget names of things, forget why they walked into the room. Few people are unable to multitask, have trouble focusing, reading and have to write down a list of things to do.


The cause of chemo brain is controversial. Through a brain imaging study and very detailed cognitive tests, Dr. Rugo found that, in addition to some part of it being due to chemotherapy or radiation, the impairment in executive brain function is also contributed to a large extent by antidepressants, lack of sleep, menopause issue including hormone therapy, which is unavoidable in hormone receptor sensitive cancers.

Scientists are trying to explain the mechanisms involved in chemo brain. In a recent study, Andres et al. (2014) explains, Cisplatin – a commonly used chemotherapeutic drug, achieves high concentrations in brain. He found that even low doses of this drug cause loss of dendritic spines and synapses– essential for neuronal transmission and brain functioning, within 30 minutes of exposure. The group noticed that at clinically relevant doses, this drug caused reduction in dendritic branches. So, this damage to the synapse and dendrites by chemotherapeutic drugs may be the reason behind chemo brain or impaired cognitive function observed after chemotherapy.

Moreover, specific parts of the brain involved in memory storage such as the parietal cortex – the major storage site of visuo-spatial memory and prefrontal cortex are seen to be affected by chemotherapy-induced impairment, leading to chemo fog (Raffa, 2013).

Now, does it really go away?

Dr. Schattner believes most people who receive chemo do well with the chemo and it is often not as bad as people expect. Most people often are relieved after the first dose. She believes that if the symptoms are reported to the doctor early, your doctor might help you by changing either the dose or the frequency of chemotherapy.

However, Dr. Rugo says that changing the dose or the schedule of chemo may reduce the effectiveness of chemo and so avoided. Still, in some severe cases where chemo is severely affecting quality of life, such changes may be desired.

The field of chemotherapy and cancer treatment has changed overtime according to Dr. Rugo. Earlier, heavy doses – almost ten times more than current doses – were given to patients, which lead to severe side effects such as chemo brain. Moreover, the growth factors that are available today to improve and keep the blood cell count strong after chemo, were not readily available then. Keeping the blood cell count maintained by these growth factors has helped to reduce the severity of chemo fog along with other toxic side effects of chemo lately.

Dr. Rugo assures that the current standards of chemo treatment that is given now is much improved, and has modest side effects that can be resolved overtime.  Patients may notice some short-term effects, which can be countered by relatively simple measures that, she suggests, should be incorporated in our daily lives, whichever way we age. She encourages patients to join the programs that are trying to help people with their executive cognitive functions through little mind games like Sudoku and crossword puzzles – aiming at improving brain focus.

Listen to the entire show HERE!



1) Andres ALGong XDi KBota DA. (2014). Low-doses of cisplatin injure hippocampal synapses: A mechanism for ‘chemo’ brain? Exp Neurol., Mar 2. pii: S0014-4886(14)00065-X. doi: 10.1016/j.expneurol.2014.02.020. [Epub ahead of print]

2) Raffa RB. (2013). Cancer ‘survivor-care’: II. Disruption of prefrontal brain activation top-down control of working memory capacity as possible mechanism for chemo-fog/brain (chemotherapy-associated cognitive impairment). J Clin Pharm Ther. Aug; 38(4):265-8. doi: 10.1111/jcpt.12071. Epub 2013 May 8.

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