The largest genetic analysis of Alzheimer’s disease to date has doubled the number of genes tied to the late-onset variant of the disease. Researchers hope that this new information will shed light on how this devastating and common brain condition develops.

The study, pioneered by the International Genomics Project and Cardiff University in the U.K., includes data from 145 academic centers around the world. Researchers, including many of the world’s leading experts on Alzheimer’s, examined genetic data gathered from over 74,000 people and found 11 new genes.

Researchers noted several surprising discoveries within their data, including that some of the newly identified genes are involved in regulation of the body’s immune system. One particular gene variant helps govern the histocompatibility complex region of the brain, which partially determines how white blood cells interact. This part of the brain also appears to play a role in other neurologic disorders, including multiple sclerosis and Parkinson’s disease. The new results reinforce the idea that the immune system could play a significant role in the development of Alzheimer’s.

In total, 21 different genes that raise Alzheimer’s risk have now been identified. Scientists in this study also identified an extra 13 that may also be linked to the disease, but they require further research. The researchers also hope to further investigate genes linked to early-onset Alzheimer’s disease, which generally appears in the 40s and 50s.

As many as five million Americans suffer from Alzheimer’s, and it is the most common type of dementia in adults over the age of 60