Researchers were looking for changes to structures found deep in cells called telomere lengthh, which is used to measure cell aging. Previously observed changes to the telomere length could not be linked to lifestyle changes like smoking, and this new study will help better understand the aging process of cells.
Josine Verhoeven from the VU University Medical Center in the Netherlands and other researchers in the U.S. studied 2,407 people; some who were currently depressed, some who had experienced depression in the past and others who had never experienced depression.
Telomeres, which cap the ends of chromosomes, protect against unwanted loss of vital genetic code during cell division. When cells divide, the telomeres get shorter and shorter, making them useful markers for aging.
Researchers found that people who were depressed or had experienced depression in the past had much shorter telomeres as compared to those who weren't depressed. They published their findings in the journal Molecular Psychiatry.
"This large-scale study provides convincing evidence that depression is associated with several years of biological aging, especially among those with the most severe and chronic symptoms," the researchers wrote.
It appears likely that only a major depressive disorder can cause changes in the telomere length, but it is unclear whether this aging process is harmful and if it can be reversed.