A rare mutation of a gene that’s normally linked to inflammation could triple the risk of Alzheimer’s disease, according to new research from an international team of scientists.

Less than 1 per cent of the population has the gene variant, called TREM2. Scientists hope that by studying the gene they will better understand how Alzheimer’s attacks the brain -- and find a way to stop it.

Their findings were published Wednesday in the New England Journal of Medicine.

About 30 million people around the world have Alzheimer’s, and that number is expected to rise to 35 million in the next three years.

The incurable disease first destroys the mind’s ability to remember. Over time, as brain cells are attacked, symptoms worsen and patients lose more of their mental abilities until they are entirely dependent on caregivers.

Until now, it’s been commonly thought that the disease is caused by Amyloid plaques -- a sticky, toxic material. Based on this theory, pharmaceutical companies have spent hundreds of millions of dollars testing medications to treat Alzheimer’s, but most attempts have failed clinical studies.

The new research suggests those experimental treatments were pointed in the wrong direction, and that TREM2’s role suggests inflammation could be the main culprit.

“What we are now finding out from genetic study is that inflammation is an important part of the disease itself,” Dr. Peter St. George-Hyslop of the University of Toronto told CTV News. “It starts early, and it is part of the way the disease actually happens.”

TREM2 has been previously linked to other forms of dementia, and was first found by researchers with Iceland-based deCODE Genetics Inc., who mapped the genetic code of 2,200 people.

Other scientists searched for the gene variant in 3,550 Alzheimer’s patients and people suffering from other types of dementia, and found it was more common in those with Alzheimer’s.

Study subjects who were found to have TREM2, but did not suffer from Alzheimer’s, still had lower mental function than those without the gene variant.

Dr. Lili-Naz Hazrati, of the University Health network, is hopeful that studying TREM2 could lead to a major breakthrough in fighting the disease.

“We are finding different components of the disease and yes, we are very optimistic that we are going towards a treatment for Alzheimer’s.”

However, Dr. Rudolph Tanzi, a Harvard Medical School geneticist, was more cautious.

He told The Associated Press he would prefer to “see more evidence” that TREM2 was linked to Alzheimer’s and not one of the other forms of dementia already connected to the gene variant.

With a report by CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip, and files from The Associated Press