The scientists found that people who had been depressed at any point in time had significantly shorter telomeres than people who had never been depressed. The average degradation—apparent even after taking lifestyle factors like smoking and drinking into account—amounted to four to six years of additional aging. “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,” says researcher Josine Verhoeven. An important next question is whether this cellular aging can be reversed; past studies have demonstrated that a healthier diet, exercise, and stress management may lengthen telomeres.