New forms of genetic testing could allow people to discover their risk of developing Alzheimer’s at a particular age, scientists have said.

An individual’s genetic data can be used to estimate how likely they are to develop the debilitating disease in the future, according to a new study published in Plos Medicine.

Alzheimer’s disease is the most common form of dementia, which mainly affects people over 65 and can cause a deterioration in memory, thinking and behaviour.

Dementia affects 850,000 people in the UK and recently overtook heart disease to become the leading cause of death in England and Wales.

Rahul Desikan, a researcher from the University of California, analysed genetic data from more than 70,000 elderly people, some who had Alzheimer’s and some who didn’t.

By identifying known genetic risk factors for the disease in each person’s genetic “fingerprint”, he and his team created a scoring system known as the polygenic hazard score (PHS).

What is dementia?

The researchers then combined this score with statistics on the incidence rates of the disease to predict an individual’s Alzheimer’s risk and even predict the age of the onset of the disease.

They tested their risk calculations in two independent groups of patients and found people with the highest score were several times more likely to develop Alzheimer’s than those with lower scores.

People with the highest PHS score were also found to have an earlier than expected age of onset of the disease by up to 10 years.

“Our genetic risk score may serve as a ‘risk factor’ for accurately identifying older individuals at greatest risk for developing Alzheimer’s, at a given age,” Dr Desikan told The Independent.

“This score may also be helpful for identifying non-demented older individuals at greatest risk for developing Alzheimer’s neurodegeneration.”

Dr Desikan said while there may be “justified fear” among patients about finding out they have a disease for which there is currently no cure, “knowing your ‘personalised’ risk for Alzheimer’s can really help with planning for the future.”

“For example, if you know that you are at elevated risk for this disease, you may want to make decisions on making a will, getting your finances in order, figure out when to stop driving and perhaps reprioritise your life,” he said.

Dr James Pickett, head of research at the Alzheimer’s Society, said the study was “fairly successful at predicting the likelihood of someone developing dementia over the coming year”.

He said the study, which focused primarily on individuals of European descent living in the US, “needs to be tested further in mixed, non-US populations”.

“This genetic risk score could help identify people to take part in research studies, but is not opening a door to genetic testing for dementia risk in the clinic,” he added.

“For anyone concerned about dementia the first step is to visit your GP. If you’re looking for ways to reduce your risk, remember what’s good for your heart is good for your head, and it may be possible to lower your risk by staying active, eating well and learning new skills.”

Six ways to help reduce the risk of dementia Show all 6 1 /6 Six ways to help reduce the risk of dementia Six ways to help reduce the risk of dementia Moderate, regular exercise Last year, a study found that walking briskly for 30 to 40 minutes a day, three times a week, was all it took to “re-grow” structures of the brain linked with cognitive decline in later life. Researchers have also said statins, designed to help those with heart conditions, may play an additional role in protecting the brain from dementia. Getty Images Six ways to help reduce the risk of dementia Quit smoking A review of studies relating smoking and dementia found that (when you remove studies funded by the tobacco industry) smokers have a significantly greater risk of dementia. Getty Six ways to help reduce the risk of dementia Protect your head A variety of observational studies have shown that professional boxers and war veterans are at greater risk of dementia due to repeated concussion and traumatic head injuries. Rex Six ways to help reduce the risk of dementia Puzzles and crosswords In 2010, studies suggested people who do puzzles and crosswords may stave off dementia for longer. However, the same study also found they may experience a more rapid decline once the disease sets in. Crosswords and Puzzles from The Independent can be solved here Getty Images Six ways to help reduce the risk of dementia A healthy lifestyle Dr Laura Phillips of Alzheimer’s Research UK says a healthy lifestyle is best for preventing dementia: “Eating a balanced, healthy diet, exercising regularly, not smoking, and keeping blood pressure and weight in check.” Getty Six ways to help reduce the risk of dementia A Mediterranean diet Research has suggested that a Mediterranean diet – rich in fish, fresh fruit and vegetables, whole grains, nuts and seeds – may reduce the risks of dementia. However NHS Choices has rpeviously warned some of the media coverage of this diet may overstate its benefits. Rex

Early diagnosis of dementia can help patients receive treatment to help with symptoms more quickly and help them and their families to develop coping strategies, which in some cases can save lives.

Professor Paul Morgan, director of the Systems Immunity Research Institute at Cardiff University, said the study “adds to the strong evidence that an approach that takes into account the polygenic nature of Alzheimer’s disease can be a useful way of aiding risk prediction”.