Both conditions are characterised by the build-up of harmful, misshapen proteins in the brain which eventually cause the nerve cells around them to die, leading to a loss of brain function. But tests on mice with Prion disease, which is rare in humans but affects the brain in a very similar way, found that a new drug could stop the deterioration. Although the therapy has yet to be tested on humans and would take many more years to develop, independent scientists claimed it could ultimately lead to the first effective treatment to control and prevent conditions like Alzheimer’s.

Prof Roger Morris, acting head of the chemistry department at Kings College London, who was not involved in the study, said it could be “judged by history as a turning point in the search for medicines to control and prevent Alzheimer’s Disease”.

The drug, developed by researchers from Nottingham and Leicester Universities, is administered by mouth and targets the mechanism which causes the death of brain cells.

In mice with Prion disease, misshapen proteins accumulate in the brain, prompting it to shut off the production of new proteins as a defence mechanism.

Usually the brain would resume its production once the blockage had cleared, but in diseased mice the faulty proteins keep accumulating and prevent it from doing so.

This means brain cells are starved of the new, healthy proteins they need in order to survive.

In the new study, published in the Science Translational Medicine journal, the team gave the mice an oral drug which prevented the brain from “switching off” its protein production.

Writing in the Science Translational Medicine journal, they reported that it was able to stop the progression of the disease across the whole brain.

However the drug compound, developed by GlaxoSmithKline for a different purpose, also had side-effects including substantial weight loss and mild diabetes caused by damage to the pancreas.

Researchers said mice with Prion disease were a good model for himans with Alzheimer’s and Parkinson’s because all three diseases involve a similar build-up of misshapen proteins.

Prof Giovanna Mallucci, who led the study, said: “We’re still a long way from a usable drug for humans – this compound had serious side effects…[but] developing drug treatments targeting this pathway for prion and other neurodegenerative diseases is now a real possibility.”

Prof Morris added: “This is the first convincing report that a small drug, of the type most conveniently turned into medicines, stops the progressive death of neurons in the brain as found, for instance, in Alzheimer’s Disease.

“This finding, I suspect, will be judged by history as a turning point in the search for medicines to control and prevent Alzheimer’s Disease.”

The Telegraph