Cold-water swimmers have long professed its benefits, from improving the mood to boosting the immune system. Now they have another incentive to brave the icy water: it may also protect the brain from dementia.

Scientists conducted tests on 40 people who made a practice of swimming daily in an unheated north London lido in winter, and found their blood had elevated levels of a brain protein called RBM3. Known as the “cold-shock” protein, because its production is triggered by a drop in core body temperature.

RBM3 plays a crucial role in restoring connections in the brains of animals coming out of hibernation. Its impact on human brains has never been tested, but in tests on mice bred to develop Alzheimer’s, those with raised levels of RBM3 experienced significantly less synapse and brain cell depletion than other mice.

Achieving a natural boost in RBM3 is not safe or easy: it requires the body to enter a hypothermic state. However, the researchers, at Cambridge University’s UK Dementia Research Institute, hope that if their findings are confirmed, it might be possible to develop a drug that mimics the protective effects of RBM3.

My comment:  Or move to the south coast of England and swim in the sea every morning in winter?  After the hospital deals with your hypothermia you will be in good shape.