A new study found that people who had experienced depression had significantly shorter telomeres, representing about 4 to 6 years of accelerated aging at the cellular level. Telomeres are structures at the end of chromosomes that protect DNA from damage. Shorter telomeres have been linked to aging. The study of over 2,400 people showed that those with a history of depression had telomeres about 83 to 84 base pairs shorter than those without depression, even after accounting for other lifestyle factors. While the study did not prove cause and effect, depression is known to disrupt many physical systems, and these findings suggest psychological distress from depression may lead to accelerated biological aging.