A STUDY analysing the DNA of more than 300,000 individuals has uncovered three new genes associated with Alzheimer's disease.

Two of the genes are already targeted by drugs used to treat other conditions, paving the way to potential new avenues for research into the degenerative condition.

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There are currently no treatments to slow or stop the progression of Alzheimer’s disease, the most common form of dementia.

The research, led by scientists at Edinburgh University in collaboration with colleagues in Australia and New York, sifted through DNA samples of 300,000 people held in the UK Biobank and honed in on those whose mother or father had developed the disease.

On an individual level, having a parent with Alzheimer’s disease is not linked to a significantly greater risk of succumbing to the illness.

However, since most of the volunteers who have donated genetic samples to the Biobank as part of research studies are comparatively young, there are very few belonging to Alzheimer's patients.

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Combining data from thousands of people whose parents developed the disease enabled the researchers to pinpoint genetic patterns relevant to the disease.

The team then combined results from their new analysis with data from an existing genetic study involving 70,000 people with and without Alzheimer’s disease.

The findings highlight three new gene variants that may play a role in Alzheimer’s risk, in addition to around 30 previously discovered.

Dr Riccardo Marioni, an expert in genetics at Edinburgh University, said: “New genetic discoveries can provide vital clues to the biological processes involved in Alzheimer’s, but our genetic makeup is not the only factor that affects our risk of the disease.

"We are now working to combine genetic data and information about people’s lifestyle to produce more comprehensive and personalised picture of Alzheimer’s risk.”

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Dr Sara Imarisio, head of research at Alzheimer’s Research UK, which part-funded the study, said: “The next step will be for molecular scientists to assess how these genes might contribute to the development of Alzheimer’s and fit in to the existing picture of the disease.

"Interestingly, two of these genes are targeted by drugs that are used to treat other conditions, signalling a potential direction for research into new Alzheimer’s treatments."

It comes after new study shed doubt on the belief that exercise can slow cognitive decline.

A trial in England involving nearly 500 participants with mild to moderate dementia found that there was no significant difference after 12 months between those assigned to a supervised exercise regime which included 60-90 minute group sessions in a gym twice a week, and those who continued with their usual care.