The crushing transformation that comes with depression may cause an alteration in mitochondrial DNA.
A team of scientists led by the University of Oxford's Dr. Jonathan Flint was looking at a previous study to determine if there was a particular gene associated with depression, according to Medical Daily.
This study featured thousands of Chinese women suffering from severe depression, sometimes caused by adolescent sexual abuse.
After comparing the DNA of these patients to a healthy control group, the researchers noticed the depressed women had more DNA in their mitochondria, which converts food into energy for cells.
Mitochondria increase in number when the body is under stress and in need of more energy.
Dr. Flint said,
We were surprised. So surprised it took us a long time to convince ourselves it was real.
They also found the depressed women had shorter telomeres, which are the caps at the ends of chromosomes that keep them intact.
Telomeres shorten as metabolism decreases with age.
A test was then conducted on laboratory mice to confirm these findings.
The mice were put under stress for four weeks, and sure enough, they exhibited the same changes in mitochondrial DNA and telomeres, IFL Science reports.
These changes proved only temporary, however.
Once the researchers administered an anti-stress hormone and placed the mice in a stress-free environment, their DNA went back to normal.
These findings suggest what was once viewed as a predominantly mental illness is really rooted in the impact of stress on one's metabolism. They suggest the body responds to environmental stress with bouts of depression.
This led Dr. Flint and his team to wonder "how [molecular markers] change over time -- before, during and after a depressive illness."
They inferred a decrease in mitochondrial DNA and increase in telomere length should be the paramount effects of future anti-depressants.
Such medications will hopefully be created very soon because if depression shrinks telomeres, it can take years off of patients' lives.
This study was originally published in the journal, Current Biology.