It turns out that depression might not just be changing people mentally. According to a report put together by scientists at the Wellcome Trust Centre for Human Genetics (WTCHG) it could also be leaving a mark on your DNA.
According to Current Biology, the discovery was made during the examination of the DNA of 11,000 people in an attempt to isolate a gene that could be responsible for increased risk of depression. Instead the researchers found that stress-related depression correlated with an increased amount of mitochondrial DNA. Apparently stress means that mitochondria struggle to effectively produce energy for cells, and so the body creates more to try and compensate.
The finding was, of course, met with some scepticism, and scientists admitted that they needed quite a big of convincing before realising it was more than just a coincidence.
They decided to test the hypothesis on mice, and subjected them to four weeks of stress. As expected there was an increase in michondrial DNA in the cells of the mice, along with another unexpected discovery: their telomeres had reduced in length. For those who don't already know, telomeres are 'caps' on the end of DNA strands that shield chromosomes from degradation. Every time a cell makes a copy of itself the telomere gets a little bit shorter until the cell is unable to divide any further.
That means telomere erosion can cause a decrease in lifespan. Thankfully researchers also discovered that this damage to telomeres and mitochondrial DNA is reversible, and after removing the mice from a stressful environment their DNA recovered.
So what does this mean for depression? It means that there is potential for better treatment of the condition in the future, and since the DNA changes it causes are reversible it's possible to assess the level of success on a cellular level. [Current Biology via IFLS]