British researchers have identified a series of genes that predict Alzheimer’s disease years before symptoms appear.

The unique “gene signature” for the leading cause of dementia, discovered by brain scientists from King's College London, could point the way to a blood test that might one day be used to identify individuals at risk early.

Doing so could speed drug treatment which can delay the progression of Alzheimer’s – medications that are most effective when taken early in the development of the disease.

The findings, published in the journal Genome Biology, are based on analysis of 150 genes associated with “healthy aging” in a group of 65-year-olds that reduce their risk of developing age-related diseases, such as dementia.

In comparing the genetic profiles of the study participants, the researchers found those later diagnosed with Alzheimer's had an altered “healthy aging” gene signature in their blood -- suggesting significant association with the disease.

"Our discovery provides the first robust molecular 'signature' of biological age in humans and should be able to transform the way that 'age' is used to make medical decisions. This includes identifying those more likely to be at risk of Alzheimer's, as catching those at 'early' risk is key to evaluating potential treatments, " said lead researcher James Timmons.

"This is the first blood test of its kind that has shown that the same set of molecules are regulated in both the blood and the brain regions associated with dementia, and it can help contribute to a dementia diagnosis. This also provides strong evidence that dementia in humans could be called a type of 'accelerated aging' or 'failure to activate the healthy aging program.' "