A clearer picture of what causes Alzheimer’s disease is emerging after the largest ever analysis of patients’ DNA. A massive international collaboration has now doubled the number of genes linked to the dementia to 21.
The findings, published in the journal Nature Genetics, indicate a strong role for the immune system. Alzheimer’s Research UK said the findings could "significantly enhance" understanding of the disease. The number of people developing Alzheimer’s is growing around the world as people live longer.
However, major questions around what causes the dementia, how brain cells die, how to treat it or even diagnose it remain unanswered.
"It is really difficult to treat a disease when you do not understand what causes it," one of the lead researchers, Prof Julie Williams from Cardiff University, said. The genetic code, the instructions for building and running the body, was scoured for clues.
A group – involving nearly three quarters of the world’s Alzheimer’s geneticists from 145 academic institutions – looked at the DNA of 17,000 patients and 37,000 healthy people.
They found versions of 21 genes, or sets of instructions, which made it more likely that a person would develop Alzheimer’s disease. They do not guarantee Alzheimer’s will develop, but they do make the disease more likely.