A new DNA test could help identify at birth which people are most likely to develop Alzheimer’s later in life.
For some babies, the risk that they will develop Alzheimer’s before their 80th birthday is very small. For others, the odds are much greater.
Scientists now have a genetic test which determines the likelihood of an individual developing Alzheimer’s at different stages of the person’s lifetime.
At this time, the estimates that the test produces are vague and are only probabilities rather than certainties. However, experts believe that the research conducted was an important step towards early identification and treatment of patients at a stage where drugs or changes to a person’s lifestyle could still make a difference.
Alzheimer’s in the UK
About 850,000 people suffer from dementia in the UK and of these, around two thirds have Alzheimer’s. There is currently no cure for the condition but some scientists are interested in treatments that could be used at the earliest stages, while there are no obvious symptoms. Finding patients who are in this phase can be difficult, but scientists think that examining a person’s DNA could help. While Alzheimer’s affects about one in eight people over the age of 65 and two in five over the age of 85, the risk varies from one person to the next. DNA is one of the best ways of identifying that risk.
Up until recently, scientists have been looking at a mutant form of the APOE gene which can be found in around a quarter of all cases. However, two years ago a group of academics published a tool which calculated a person’s risk of developing the disorder based on 31 genetic markers and two APOE variants. The tool was found to be about 80% accurate.
The most recent work has gone a step further – breaking the genetic risk down into age groups which makes a significant difference to the accuracy of the polygenic hazard score (PHS). The team based their work on 17,000 subjects with Alzheimer’s and 37,000 without, demonstrating that the people with high risk scores would develop Alzheimer’s 10 to 15 years before the people with the lowest scores. A person in the safest 25% has an 80% chance of avoiding developing Alzheimer’s up to the age of 85 – while the chance of avoiding the disease dropped to 15% for those in the riskiest 25%.
The team noted that for any individual with a given age and genetic information they could calculate a personalised, annualised risk for developing Alzheimer’s. Of note, however, the research was carried out exclusively on Americans with European ancestry – and the researchers would need to analyse a more diverse group to see the effect on findings.
The research was published in PLOS Medicine Journal.
No cure for dementia
Although the risk for dementia increases with age, this debilitating disease can affect younger and older people alike. A Lasting Power of Attorney (LPA) allows you to nominate someone you trust to make decisions for you if you should lose mental capacity because of dementia or for some other reason such as an accident or stroke. There are two types of LPA: one for financial decisions and the other for decisions relating to health and care. Visit our LPA page or ask our Later Life Planning team for more information.