It suggested RBM3 could be the key to the formation of new connections.
They proved the link in a separate experiment which showed brain cell deaths in Alzheimer’s and prion disease could be prevented by artificially boosting RBM3 levels in mice.
It was a major breakthrough in dementia research, and their findings were published in the scientific journal Nature.
Prof Mallucci believed a drug which prompted the production of RBM3 might help slow – and possibly even partially reverse – the progress of some neuro-degenerative diseases in people.
RBM3 had not been detected in human blood, so the obvious next step was to find out whether the protein is present in the human population.
In an interview on the BBC Radio 4 Today Programme, Prof Mallucci explained that she would like to test the role of RBM3 in humans – but that ethical guidelines would make it very hard to get permission to make people hypothermic.
Step forward Martin Pate, one of a small group who swim throughout the winter at the unheated open-air lido on Hampstead Heath in London.
He and the other swimmers voluntarily made themselves hypothermic on a regular basis he told her in an email, and would therefore be ideal subjects of a study.
Prof Mallucci agreed, and during the winters of 2016, 2017 and 2018, her team tested for the protein in winter swimmers.
The researchers used members of a Tai Chi club who practise beside the pool but never actually swim, as a control group.
The Cambridge team found that a significant number of the swimmers had markedly elevated levels of RBM3.
All of them become hypothermic, with core temperatures as low as 34C.
None of the Tai Chi group showed an increase in RBM3 levels or experienced these very low body temperatures.
Could cold slow dementia?
The Cambridge work on winter swimmers has been shared in online lectures
but has not yet been published in a scientific journal.
A number of other researchers have found similarly higher levels of RBM3 in babies and heart and stroke patients who have been made hypothermic.
What these findings show, says Prof Mallucci, is that – just like hibernating mammals – human beings produce the “cold-shock” protein.
But the risks associated with getting cold outweigh any potential benefits, so cold water immersion is certainly not a potential dementia treatment, she says.
The challenge now, she says, is to find a drug that stimulates the production of the protein in humans and – more important still – to prove it really does help delay dementia.
Dementia is predominantly a disease of the old, so even a relatively short delay in the onset of illness could have huge benefits for individuals, and the wider population.
Prof Mallucci says: “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.”