A large-scale analysis of patient's DNA could provide a clear picture of the causes behind Alzheimer's disease, it is hoped.
Collaboration between international researchers has found a number links to the cognitive condition.
Published in the Nature Genetics journal, the study indicates that a person's genetic code would play a part in a person's vulnerability to dementia.
Geneticists from 145 institutions examined DNA from 17,000 Alzheimer's patients and 37,000 people with normal health.
Some 21 genes were found which make it more likely that a person will go onto develop the condition.
Professor Julie Williams, head of neurogeneration at Cardiff University, told the BBC that looking at the function of these genes in the body could enable scientists to work out what failings in them made Alzheimer's disease more prevalent.
"We've doubled the number of genes discovered and a very strong pattern is emerging," she added.
"There is something in the immune response which is causing Alzheimer's disease and we need to look at that."
Dr Eric Karren, director of research at the charity Alzheimer's Research UK, said mapping the genetics of Alzheimer's highlights new biological processes that could increase understanding of the disease.
He believes, that, while not conclusive, the study has the potential to pinpoint the exact genes involves so that new medications can be worked on.
It's a view shared by Dr James Pickett, head of research at the Alzheimer's Society, who described the analysis as being able to "open up new avenues to explore in the search from treatments".
Around 820,000 people are currently living with some form of dementia in the UK and that figure is expected to rise above the one million mark by 2021 if a suitable cure is not found.
Alzheimer's disease is the most common form of dementia, affecting 62 per cent of patients.
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