Alzheimer's picture becomes clearer

Scientists believe they now have a clearer picture of genetic causes of Alzheimer's disease. This follows the biggest-ever study into the condition.

There are an estimated 800,000 people with dementia in the UK, with 62% of these having Alzheimer's, according to the Alzheimer's Society.

An international team discovered 11 new genes that are linked to Alzheimer's disease, the most common form of dementia, using information from nearly 75,000 people across 15 countries.

The study builds on the genome-wide association analysis study that, since 2009, has discovered 10 genes known to be linked to Alzheimer's.

Professor Julie Williams, the head of neurodegeneration at the Cardiff University School of Medicine's Medical Research Council (MRC) Centre on Neuropsychiatric Genetics and Genomics, spearheaded one of four worldwide research groups.

She said the findings will identify new mechanisms underlying Alzheimer's disease.

Prof Williams said: 'What surprised us most about the findings was the very strong pattern that showed several genes implicating the body's immune response in causing dementia.'

21 genes known to raise risk of Alzheimer's

Scientists now have a total of 21 published genes known to raise the risk of developing Alzheimer's. While having any of these genes does not necessarily make a person develop the disease, their presence allows researchers to try to understand what the underlying causes might be.

But a big proportion of the genetic risk for the disease remains unexplained. Prof Williams said additional studies are still required to find the other genes involved before a complete picture can be built up.

The next part of the research will concentrate on people with early onset Alzheimer's - people aged in their 40s and 50s afflicted with more severe forms of the condition.

The research, part-funded by the Medical Research Council, the Welsh Government and Alzheimer's Research UK, is published in the Nature Genetics journal.

Copyright Press Association 2013