A consortium of Alzheimer's researchers, including a team from Canada, has identified five additional genes that each add to risk of dementia later in life.

Until recently, only four genes associated with late-onset Alzheimer's had been confirmed, including SORL1, which was discovered in 2007.

"This represents new information about the pathway that causes Alzheimer's," said Dr. Peter St. George-Hyslop of the University of Toronto's Tanz Centre for Research in Neurodegenerative Diseases.

"Several of the genes were genes we didn't know about and they are going to quite richly tell us more about the disease. I think they are going to be very valuable in the next few years and might even lead us to diagnostic or treatment markers with potential to slow down the disease."

"Now we will need to go back and look at a whole new range of possibilities," added St.George-Hyslop, who led the Canadian cohort of researchers. "Things that we thought were end stage of life events will have to be looked at again. We have to do a full scale re-think."

The study, done by the Alzheimer's Disease Genetics Consortium, detailed the genetic analysis of more than 11,000 people with Alzheimer's disease and a nearly equal number of elderly people who had no symptoms of dementia. It also confirmed data to bring the total number of people analyzed from the United States, Canada, the United Kingdom and Europe to 54,000.

The consortium discovered four extra genes in one study while another study, released on Sunday, uncovered a fifth.

St. George-Hyslop believes that, with a lot of hard work, there could be breakthroughs in as little as five years because medical researchers already have a lot of background in the biology of the brain and dementia: "We are not starting at zero."

The researchers' aims are twofold:

• Identify new Alzheimer's disease genes and gain major clues to the disease's underlying cause, information critical to finding better drugs to treat dementia.
• Learn to predict who will develop Alzheimer's disease, which will be important when preventive measures become available.

Canada has top researchers

One of the challenges will be scrounging around for the money to fuel the continued research, St. George-Hyslop says.

"We have very good researchers here in Canada and if we were properly funded we could provide solid and substantive contributions, even play a prominent role as Canadian researchers have in the past," he said.

The study that discovered the four genes is a result of a large collaborative effort with investigators from 44 universities and research institutions in the U.S. and Canada. It is the culmination of about five years of research on Alzheimer's disease and is published in the current edition of the journal Nature Genetics.

That study was partially funded by the Canadian Institutes of Health Research and the Alzheimer Society of Ontario.

About 500,000 Canadians currently suffer dementia, a number that will grow as baby boomers age.

During the federal election campaign, the Alzheimer Society of Canada is asking all candidates to take a position on a national strategy to make dementia a government priority.

With files from the CBC's Mary Sheppard