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Chemo-brain is the term sometimes used to describe those symptoms experienced by individuals who have undergone chemotherapy. They complain that their thinking skills are clouded with disrupted attention, short-term memory loss and a slower speed of thinking.

Enduring chemotherapy to then discover that one’s thinking skills are significantly impaired can lead to frustration and worry that our brains cognitive skills may be permanently affected. Up until now there has been little to explain why chemo-brain occurs and what if anything can be done about it.

A new study published in the European Journal Of Neuroscience indicates that chemo-brain occurs because the chemotherapy appears to impair neurogenesis: the production of new brain cells. In addition, disruption of what are called theta brain rhythms in the hippocampus, the area of the brain associated with the formation of new memories occurs. The role of theta brain waves is believed to be important for connecting information across brain regions.

Using a specific chemotherapy drug called Temozolomide (TMZ) in rat studies, the researchers were able to demonstrate a reduction in both neurogenesis (by 34%) and theta activity with associated disruption to learning, especially for learning of more complex tasks. No such disruption was seen however, for previously learned associations.

The good news is that this disruption is temporary only, which will be a relief to those undergoing chemotherapy who are experiencing these thinking problems, at a difficult time when they are already having to cope with coming to terms with undergoing treatment plus trying to lead as normal a life as possible.

The researchers comment that while up to 70% people who have cancer therapy will experience some short-term memory loss and disordered thinking, up to 50% experience significant and measurable reduction in cognitive skills including attention, learning, memory and processing speed. In addition there are approximately 15% who will experience longer lasting cognitive disturbance, as a result of undergoing chemotherapy.

When I was working as a G.P. patients not infrequently would ask me what they could do to help their brain recover from this chemo-fog. It appears that in most instances, time will allow the brain to recover. Some proponents of working memory training suggest that this specific type of brain training can help. This research appears to support the notion that stimulating the working (or short term) memory would be helpful here. It will be interesting to see whether further research does in fact support this.

“Chemotherapy disrupts learning, neurogenesis and theta activity in the adult brain” by Miriam S. Nokia, Megan L. Anderson, Tracey J. Shors in European Journal of Neuroscience. Published online December 2012 DOI: 10.1111/ejn.12007

Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, podcaster, keynote speaker and best-selling author. Her new book 'Thriving Mind: How to Cultivate a Good Life' (Wiley) is available online and at all good bookstores.

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