Researchers in Dublin have developed a new blood test that can diagnose Alzheimer's disease in its early stages.

The team from the Royal College of Surgeons in Ireland (RCSI) says that the test can also predict how the disease will progress.

Alzheimer's disease, which is the most common form of dementia, is a progressive and irreversible disease of the brain. It is characterised by a loss of intellectual function, chronic memory loss, language deterioration and personality change.

An estimated 20,000-25,000 people in Ireland are affected and the disease costs the health system up to €400 million every year to treat. However, no new therapy has passed clinical trials in 20 years and this has largely been blamed on the fact that therapies are usually aimed at the advanced stages of Alzheimer's when damage to the brain has become irreversible.

According to the RCSI researchers, for treatments to be successful, the early stages of the disease, before full onset, need to be targeted. However, there is currently no blood test available to diagnose Alzheimer's.

They have developed a blood test that appears to do this. It focuses on concentration changes of a small molecule in the blood that can diagnose the disease at an early stage when other symptoms are mild.

"Our research carried out over the past four years has identified changes in blood levels of a small molecule called microRNA, which is able to diagnose Alzheimer's disease at a very early stage and is able to distinguish Alzheimer's from brain diseases with similar symptoms," explained the study's principal investigator, Dr Tobias Engel, of the RCSI.

He noted that people are living longer today and as a result, the incidence of age-related brain diseases, such as Alzheimer's, will increase.

"Research into the condition is largely focused on the development of new therapies, however, new therapies need diagnostic methods which are affordable and minimally invasive and can be used to screen large populations," he pointed out.

The research was carried out with colleagues in Spain and Dr Engel is now working on advancing the translation of this research to make it available as a test for patients.

Details of the findings are being presented at the RCSI Research Day 2018 (March 7) at the RCSI in Dublin.