Stressed girls with a family history of depression may age faster than girls without a family history of the illness, new research reveals. The study, published in the journal Molecular Psychiatry, adds to a growing body of evidence demonstrating the devastating transgenerational effects of mental illness.
The association between stress, depression and adverse physiological changes in the body is well documented. Specifically, studies have linked chronic stress to increased risk of depression, and depression to premature aging, determined by shortened telomere length.
Telomeres are structures at the end of chromosomes that protect them from deterioration. Telomeres shorten in length as we age, although oxidative stress and other DNA-damaging processes can cause them to shrink prematurely.
In fact, DNA damage caused by stressful and/or traumatic life experiences can be detected in children as young as nine years old. Using mouse models, researchers have also recently shown that prolonged exposure to stress is associated with imbalances in microRNAs that can be passed down through three generations.
However, it remains unclear as to what comes first: stress, depression, or reduced telomere length. It is also unknown whether these factors interact with one another or have the potential to produce synergistic effects.
With the aim of finding out, the team behind this latest research — led by Stanford University professor Dr. Ian Gotlib — studied these mechanisms among 97 girls aged 10-14 years who were free of depression but considered at high risk of developing depression due to a family history of the illness.
“Studying such a population is critical in assessing whether shortened telomere length is a pre-existing condition or risk factor for developing depression, or, alternatively, is a response to, or concomitant of, major depressive episodes,” the researchers explain.
Shortened telomeres ‘a potential risk factor for depression’
Dr. Gotlib and colleagues assessed the telomere length of these girls by analyzing DNA samples and then comparing them with the telomere lengths of age-matched girls who had no family history of depression. All participants underwent stress tests and were interviewed about stressful situations they had experienced. The researchers also measured participants’ cortisol levels, both before and after the stress tests.
The team found that girls at high risk of depression had shorter telomere lengths — equivalent to 6 years of biological aging in adults — compared with girls without a family history of depression. Dr. Gotlib says he was surprised by the findings. “I did not think that these girls would have shorter telomeres than their low-risk counterparts – they’re too young,” he adds.
“The results of this study indicate that healthy children at familial risk for depression have shorter telomeres than do their non-risk peers,” the authors conclude. “Thus, telomere shortening appears to be an antecedent to, and potentially a risk factor for, the onset of depression.” Furthermore, the researchers also found that girls with shortened telomere length had higher cortisol reactivity in response to stress, which is also associated with adverse health effects.
Findings have ‘important health implications’ for girls at high risk of depression
Overall, the team’s findings suggest that girls at high-risk of depression are more likely to have shorter telomere length and that stress may mediate this effect. The researchers say these findings are worrying, as telomere shortening has additional, potentially harmful health-related implications that are particularly serious given the young age of the participants.
“Telomere shortening is not only a marker of stress, but is also a mechanism of biological aging,” they explain. “Insufficient telomere maintenance can accelerate biological aging and increase individuals’ risk for experiencing age-related chronic diseases.”
As such, the team says it is important that individuals who are vulnerable to telomere shortening, such as those with a family history of depression, are identified. “Also,” they add, “it is important to follow these girls longitudinally to examine whether telomere length influences the onset of major depressive disorder and whether developing depression, in turn, contributes to further shortening of telomeres.”
Dr. Gotlib and colleagues say it may be beneficial for young girls at high risk of depression to learn stress-reduction techniques, such as attention bias training – where an individual learns to focus on the positive areas of life rather than the negative. Furthermore, physical activity and proper dietary intake have been shown to delay telomere shortening in adults, indicating that lifestyle changes may help mitigate some of the risk among girls with a family history of depression.