When Princeton University researchers analyzed data from a representative sample of 40 African-American boys enrolled in the Fragile Families and Child Wellbeing Study that followed children born in large U.S. cities between 1998 and 2000, they determined that those that lived through 9 years of age with less-stable families such as parents with multiple partners and harsh or hostile parenting styles had a higher probability of shorter telomeres compared with other children. Telomeres were, on average, 40 percent longer among children from stable families.

Telomeres are the segments of DNA at either end of a chromosome that protect the ends from deterioration or fusion with neighboring chromosomes. Shorter telomeres can decrease life expectancy by reducing the number of times our cells can divide, and scientists are discovering that a person’s living environment may lead to the condition.

Using large cohort (age group) study data from the Netherlands Study of Depression and Anxiety, another group of researchers from Amsterdam’s Vrije University found significantly shorter telomere length among those with higher stress markers; the shorter length was also associated with aging approximately 10 years faster. In addition, the scientists observed significantly shorter telomere length among people with depressive symptoms lasting longer than four years; the shorter length correlated with both longer and more severe depression.