Depression may take away years from your life, a new study that looked closely into humans' cells suggests.
Research published in Molecular Psychiatry on Nov. 12 shows that people who are or had been severely depressed had shorter telomeres, which are cellular markers that are used to measure how a cell ages.
Telomeres are shields made from DNA and protein that protect chromosomes and help keep them stable, similar to the plastic caps at the end of shoelaces. They naturally become shorter and weaker over time, leading the cell to age faster and die.
Researchers looked at almost 1,100 people who were currently diagnosed with major depressive disorder (MDD) or clinical depression, 802 people who had previously been diagnosed with MDD and 510 who never had the psychological issue. The Centers for Disease Control and Prevention estimate that about 1 in 10 U.S. adults suffer from depression at any given time.
Participants all gave a blood sample so the researchers could look at their telomeres. When all outside factors that can influence aging were ruled out, they discovered that people who currently or previously were depressed had 83 to 84 fewer base pairs of DNA in their telomeres than those who never had depression.
People typically lose 14 to 20 base pairs a year due to aging, so the researchers theorized that depression aged people an additional four to six years.
"Psychological distress, as experienced by depressed persons, has a large, detrimental impact on the 'wear and tear' of a person's body, resulting in accelerated biological aging," study author Josine Verhoeven, a researcher at the Free University in Amsterdam, told Live Science.
"The findings might help explain the variety of health complaints often experienced by people with major depression," she added.
It was unclear in the new study if shorter telomere length led to depression or depression led to fewer DNA base pairs in telomeres.
Shorter telomere length has previously been linked to an increased risk of some cancers, stroke, vascular dementia, heart disease, obesity, osteoporosis, diabetes and the common cold. A Scottish study also revealed that lower-income individuals who had a household income of less than $41,000 had their telomeres shrink faster during the course of a 10-year study than those who made more money.
Having a healthy lifestyle, on the other hand, has been linked to longer telomere lengths.
Etienne Sibellie, an associate professor of psychiatry at the University of Pittsburgh, told HealthDay that the new study was especially important because it looked at a large group of people. He was curious to see if doing things to lengthen telomeres would improve the health of these individuals.
"It's just not known whether it has an impact on cell function," he said. "If that's the case, it has potential therapeutic importance."