A landmark British study has raised the prospect of a pill that can treat brain diseases such as Alzheimer’s by halting the death of neurons.

The research, performed on sick mice, is at a very early stage and it could be a decade or more before any medicine suitable for patients is developed. But experts say the findings are highly significant, and one predicted that they would be judged by future generations as a historic turning point.

The Medical Research Council (MRC) team focused on the root cause of many degenerative brain diseases, including Alzheimer’s and Parkinson’s – abnormally shaped proteins that stick together in clumps and fibres.

When enough misshapen protein builds up in the brain, it can trigger a reaction that results in the death of nerve cells.

Other approaches have sought to stop or limit the accumulation of the abnormal protein, whose structure is folded the wrong way. Instead, the MRC researchers targeted the harmful way brain cells react to misfolded proteins. Using a drug injected into the stomachs of mice through a mouth tube, they flipped a cellular switch from “off” to “on” to prevent neurons dying.

Five weeks after treatment one group of mice remained free of symptoms such as memory loss, impaired reflexes and limb dragging. They also lived longer than untreated animals with the same brain disease.

The scientists stress human trials are a long way off and point out that the mice suffered serious side effects, including significant weight loss and raised blood sugar.

But they also believe the research demonstrates in principle the possibility of developing an oral treatment – a pill or swallowed liquid – that can protect the brain from neuro-degenerative disease.

The research, reported in the journal Science Translational Medicine, duplicated previous results achieved by the same team by means of genetic engineering.

As in the earlier study, a neurodegenerative disease caused by abnormal prion proteins was induced in the mice. Prion diseases, which include Creutzfeldt-Jakob Disease (CJD), are rare in humans but share the same underlying cause – misfolded proteins – as more common conditions such as Alzeimer’s.