It is the first accurate test to diagnose the disease when symptoms are mild.
Early diagnosis holds the best opportunity for potential future treatments and improving the quality of life for people with the disease.
Researchers at the Royal College of Surgeons in Ireland identified concentration changes in the blood of a small molecule that can diagnose the disease when other symptoms are mild.
The research is among a number of innovations to be presented at the annual RCSI Research Day in Dublin today.
The four-year study on Alzheimer’s disease was carried out by academics and clinicians from Ireland and Spain.
The project’s principal investigator, Tobias Engel, a lecturer in physiology at RCSI, said that they found changes in blood levels of a small molecule called microRNA.
They were also able to distinguish Alzheimer’s from brain diseases with similar symptoms.
Asked when the Alzheimer’s test is likely to be available, he said: “We are still at the stage of clinical testing. I would predict, if everything goes well, we are talking about five years.”
Dr Engel said research into the condition was largely focused on the development of new therapies.
“New therapies need diagnostic methods which are affordable and minimally invasive and can be used to screen large populations,” he said.
Alzheimer’s disease affects 48m people worldwide and an estimated 20,000 to 25,000 in Ireland. No new therapy has passed clinical trials in 20 years, and much of the failure in clinical trials has been attributed to using therapies when the disease is at an advanced stage and the brain damage is irreversible.
For treatments to be successful, the early stages preceding the full onset needs to be targeted but, currently, there is no blood test available to clinicians that can be used to diagnose the disease.
Also being presented at RCSI Research Day, is a new potential treatment to target resistant breast cancer discovered by college researchers.
They found that patients who did not respond well to treatment had high levels of a protein called BRD3 in their tumours.
Their study shows that combining two existing drugs may be a potential therapeutic strategy to treat this form of breast cancer.
One in three patients with a type of breast cancer called invasive lobular carcinoma do not respond well to traditional anti-hormonal treatment options.
Tríona Ní Chonghaile, a research lecturer at the RCSI’s department of physiology and medical physics, and one of the project’s principal investigators, said there was a greater increase in cancer cell death using the two drugs together.