In a paper published Tuesday in the journal Molecular Psychology, researchers in California and the Netherlands said they found an association between major depressive disorder, or MDD, and accelerated cellular aging.
Specifically, study authors said that after examining the white blood cells of more than 2,400 Dutch study participants, they found that people with clinical depression had shorter telomeres than their healthy peers.
Telomeres are strands of protective DNA that cap the tips of chromosomes within a cell. Each time a cell divides, the telomeres get a little bit shorter. Eventually the telomeres become so small that the cell begins to shut itself down.
Scientists have also linked shortened telomeres to various age-related health problems like heart disease, obesity, diabetes, cancer and mental decline. Now, researchers believe they are linked to depression as well.
While people who suffer clinical depression may avoid physical exercise and adopt other unhealthy practices like heavy drinking and smoking, study authors said those behaviors did not fully account for the rapid shortening of telomeres observed in clinically depressed study subjects.
Researchers said that based on telomere length, study subjects who suffered severe clinical depression for a period of two years actually aged seven to 10 years, when compared to healthy people.
"The most severely and chronically depressed patients had the shortest telomeres," said lead author Josine Verhoeven, a psychiatric researcher at Amsterdam's VU University Medical Center.
"Overall, this study provides convincing evidence for the suggestion than an emotional stressful condition, such as MDD, may truly impact on the physical 'wear and tear' of a person's body resulting in accelerated biological aging," wrote Verhoeven and colleagues.