Researchers in the United Kingdom say exposure to cold water may be beneficial in defending against dementia.
The key is a protein called RBM3. In a 2015 study involving mice, levels of RBM3 seem to be higher in mice after they went into hypothermia - that is, body temperature below 35 degrees Celsius - and then were carefully warmed. These mice also showed signs that neuron cells damaged by the cold had been repaired.
In another experiment, scientists took mice with Alzheimer's or prion, both neurodegenerative diseases, and raised their levels of RBM3 artificially. They then put the sick mice through the "cold shock" experience and found that some synapses between brain cells were less prone to breakage than without the higher RBM3 levels. This might mean RBM3 helps shield against brain damage.
The researchers related their work to hybernating mammals, who go into hypothermic states each winter and lose 20-30% of their synapses. Yet, the animals do not seem to be harmed by the synapse loss. It is thought that RBM3 may help them regenerate synapses.
A group of swimmers in London who take the plunge in an outdoor pool year round volunteered to assist with RBM3 research in humans. After warming up from extremely low core temperatures, the swimmers had higher RBM3 levels than people in a control group.
"If you slowed the progress of dementia by even a couple of years on a whole population, that would have an enormous impact economically and health-wise," said lead scientist Giovanna Malluci.
She recently discussed her research live on YouTube.
Malluci and her team do not recommend cold-water exposure as a treatment or prevention for dementia, noting that it poses health risks. Instead, they say, scientists may be able to find a safe way to boost RBM3 within the body.