An international team, including Australian researchers, have identified novel areas of DNA that are linked to the risk of developing Alzheimer's disease (AD) and other forms of dementia. Researchers believe that the findings could lead to a better understanding into how the debilitating disease takes hold. The research, published in Nature Genetics and released on Tuesday, was based on a two-stage study of genomes of more than 111,000 people suffering from AD and some 670,000 controls who don't have the disease, Xinhua news agency reported. The research found people with AD had numerous risk regions within their genomes which occur less among the control group. They initially found 42 risk regions, and further research in the new loci identified 31 genes that were suggestive of new genetically associated processes. One of the researchers, Associate Professor Michelle Lupton from Australia's QIMR Berghofer Medical Research Institute, told Xinhua that the findings pinpointed the actual genes and genetic regions that are contributing to heritability. Based on the findings, they refined a previously existing "genetic risk score" which is used in identifying people who are more likely to get the disease.
"As you get older, you could be diagnosed with mild cognitive impairment. So that's when people start to just see reduced cognition. Around 50 per cent of people with mild cognitive impairment may go on to get dementia, however others won't." "This shows that people who have a high-risk score are more likely to get AD within three years, so you could try to prevent them developing the disease." The research also confirmed previous findings regarding the protein amyloid-beta and tau, which build up in and around nerve cells as Alzheimer's progresses, and pointed to new evidence for the role of genes involved in inflammation. "We see that a lot of genes that are involved in inflammation in the brain contribute to AD, especially the involvement of microglia, the immune cells in the brain. It gives clues to drug targets, and what to aim for when looking for drugs to treat or prevent AD," Lupton said. Researchers said their findings suggest that AD is caused by a multitude of different factors. As one of the factors, the heritability of the disease is estimated to be between 60 per cent and 80 per cent. These newly identified genetic components provide an opportunity to determine the pathophysiological processes in the disease and to identify new biological features and new therapeutic targets through translational genomics.