Depression – not just in your head, it’s also in your genes
97 healthy girls, ages 10 to 14, had saliva DNA samples taken. About half of them had moms with histories of depression, and about half had moms who did not. None of the girls had histories of depression. (1)
The girls whose moms had suffered depression had significant reductions in the length of their telomeres. We all want to understand telomeres, the caps at the ends of our DNA strands, because the longer they are the longer we tend to live – and live freer of age related illnesses like heart disease, stroke, dementia, diabetes, and osteoporosis. The girls whose moms didn’t have histories of depression, the control group of the study, did not show the same changes in their DNA as a result of reductions in the length of their telomeres.
The researchers took the study another step: they compared both groups of girls, the former or “high risk” group and the control or “low risk” group, by measuring their response to stressful mental tasks. The children of moms with depression had significantly higher levels of cortisol, our stress hormone, released during these tasks than those in the control group; both had normal levels of cortisol before the stressful tasks.
These findings are what scientists call associations, namely highly significant events found together that are unlikely to co-occur randomly. In themselves, they don’t prove one caused the other, but they suggest that something important, not accidental, is going on. This study demonstrated shorter telomeres in daughters of moms who had depression and greater hormonal reactivity to stress in these girls.
When the girls were followed until age 18, 60 % of those in the high risk group developed depression, a condition that was not evident when they were first studied. The telomere was a biomarker, an individual hallmark that a person is at higher risk for an illness– in this case for depression. We already knew that shortened telomeres were a risk factor for chronic, physical diseases but now the evidence is emerging for its likely role in depression.
Should you go out and get your saliva tested? There are labs happy to provide the test. But your decision should depend on whether you have reason to suspect being at risk, like a family history of maternal depression – which may be all you actually need to know. But information is only valuable if we can do something about it.
And we can. We have a growing set of tools to help control our stress responses: these include yoga, yogic breathing, meditation, cognitive training techniques, exercise, diet, and working to have supportive, stable relationships, and home and work environments. People at greater risk for stress-related diseases (mind you, we all are at risk it’s just a matter of degree) would be wise to learn and master these techniques early in life, and use them to live a healthier and longer life.
We also need to better detect and treat mothers who suffer from depression. We have strong evidence that untreated depression in moms impairs their attachment to their children and is associated with these children developing behavioral and emotional problems in childhood. If the moms are properly treated not only do they do better, so do their kids.
As we try to undo a long history of stigma about mental disorders and demonstrate they are illnesses that call for identification, early intervention, effective treatment, and prevention whenever possible, this telomere study is more evidence that depression is “…not just in our heads.”
Understanding our genetic predispositions, developing reliable biomarkers, managing our environment and stresses, protecting ourselves from our harmful hormones, and having access to effective treatments are our best prescriptions for healthier and longer lives.
(1) Telomere length and cortisol reactivity in children of depressed mothers, Gotlib, IH, LeMoult, J, et al, Molecular Psychiatry advance online publication, 30 September 2014; doi:10.1038/mp.2014.119