DNA methylation plays an important role in Alzheimer's disease, researchers say.

Alzheimer's disease is characterized by memory loss and poor cognitive skills. The latest study, led by researchers at the Brigham and Women's Hospital (BWH), tried to find the epigenetic changes that help the disease develop.

DNA methylation, the addition of a methyl group (or molecule) to DNA, has previously been linked to growth of several cancers. DNA methylation acts as a switch that turns off the activity of a gene.

The researchers say that this is the first time that epigenome-wide association (EWAS) studies are used to look into the growth and development of Alzheimer's disease.

"Our study approach may help us to better understand the biological impact of environmental risk factors and life experiences on Alzheimer's disease," said Philip L. De Jager, from the BWH Departments of Neurology and Psychiatry.

The researchers explained why studying the "epigenome" is important in understanding a disease.

"There are certain advantages to studying the epigenome, or the chemical changes that occur in DNA. The epigenome is malleable and may harbor traces of life events that influence disease susceptibility, such as smoking, depression and menopause, which may influence susceptibility to Alzheimer's and other diseases," De Jager said in a news release.

For the study, the researchers analyzed 708 donated brains from subjects enrolled in the Religious Orders Study and Rush Memory and Aging Project. The researchers found some DNA methylation levels co-related with Alzheimer's disease. The team discovered biological markers for the disease in genes such as ANK1 and RHBDF2 genes as well as ABCA7 and BIN1, which have previously been linked to Alzheimer's disease.

One of the major problems with the study was that the samples were taken from dead people, meaning that the researchers can't be sure whether the changes had actually caused the disease or if it was the other way around, according to New Scientist.

The study is published in the journal Nature Neuroscience.