Excess of calcium build-up could be the cause of chemo brain fog for millions of cancer patients, study finds

Scientists think they have uncovered the cause of ‘chemo-brain’ experienced by some 75,000 cancer patients – a name given to memory and attention problems commonly found during treatment.

American researchers claim it could be linked to an excess of calcium floating around inside the brain, and that the findings might lead to new treatments to restore cognitive function in sufferers.

Calcium is an essential mineral for bone health found abundantly in dairy foods. It also serves as a crucial messenger in cells throughout the body.

However, a build-up of the nutrient is known to occur in patients with heart failure and atrial fibrillation – a common disorder that causes the heart to beat erratically.

Teams at Columbia University Vagelos College of Physicians and Surgeons and the University of Texas MD Anderson Cancer Center found that chemo also causes ‘calcium leaks’ in the brain.

The mice they tested on suffered memory problems, too, struggling with mazes and navigating obstacles. The investigators also discovered one of their drugs under development was able to reduce the calcium leaks and the cognitive symptoms in the mice.

Dr Andrew Marks, a physiology and cellular biophysics professor who co-authored the study, says: ‘As a clinician, one of the things I ask my patients with cancer is, “What is the thing that affects you most in daily life?” One thing they say is brain-fog – something a busy clinician typically doesn’t have time to address.

‘It’s a very important problem with a huge unmet clinical need.’

The study also adds weight to the argument that calcium leaks play an important role in cognitive deficits in general. Excess of the mineral inside cells is seen in patients with Alzheimer’s, long Covid and PTSD.

Cancer Research UK estimates that of the near-400,000 Britons diagnosed with cancer each year, 28 per cent have chemotherapy as part of their treatment.

Around three quarters of these sufferers report memory and thinking problems, although it tends to resolve within six to nine months of finishing the treatment, according to experts.

Other frequent chemo side effects include nausea, fatigue and hair-loss.