It is believed the drug – usually used to treat diabetes – can help to restore brain activity before symptoms of the terminal illness become established.

Research published in the journal eLife found that the drug can help to regulate the Huntingtin protein, which in a mutated form can accumulate in the brain, leading to the onset of the illness.

The study was led by the University of Dundee – working with Johannes Gutenberg University and the German Center for Neurodegenerative Diseases in Bonn, both in Germany.

Dr Ros Langston, of the University of Dundee School of Medicine, and co-author of the study, said: “This is a really important development as there are currently no effective treatments for Huntington’s patients.

“Metformin is already in the public domain and its limited side effects are already known, meaning that further studies should not take as long as those for new drugs. This means that in terms of developing therapeutic treatment for people who may have Huntington’s in their family, this is potentially very exciting news.”

From studying the visual cortex in mice treated with Metformin, researchers found that the drug helped to restore brain activity patterns and reduce erratic behaviour by controlling the Huntingtin protein.