Scientists have discovered that stress-induced depression is correlated with an increase in the length of mitochondrial DNA. Furthermore, it was observed in mice that stress is associated with a decrease in the length of telomeres.The findings were published in the journal Current Biology.
Depression leads one to a terrible roller-coaster ride, many times compared to death. The highly-ingrained emotional and mental condition seems to pervade even deeper into humans, reaching into their DNA. A new study has shown that depression temporarily modifies one’s mitochondrial DNA.
When a group of scientists from the Wellcome Trust Centre for Human Genetics (WTCHG) set out to locate the gene associated with an increased risk of depression, they were surprised to find fate bringing them to another discovery altogether. Though they did not detect the gene they aimed to identify, they found a peculiar link between depression and mitochondrial DNA. They observed that stress-related depression was correlated with an increased length of mitochondrial DNA.
The scientists analysed the DNA of more than 11 000 people, some of whom had recorded stress-related depression, and others were healthy controls.
The finding relating to the increase in the mitochondrial DNA in people with depression comes with a number of implications. Mitochondria are known as the powerhouses of cells: they house the processes that release energy allowing the cells to live. During stressful conditions, the cell organelle has to struggle to create energy as efficiently during normal times. Because of this need, the body responds by creating more and more mitochondria to compensate for the stress, and keep up with the increased energy demand.
The researchers thereafter tested these changes in mice. They subjected the mice to four weeks of stress. The results then showed that the expected increase in mitochondrial DNA happened in the mice as well. Furthermore, it was observed that their telomeres, which are found at the end of DNA strands, had decreased in length. It is to be noted that telomeres protect chromosomes from degrading and losing information; however, telomeres decrease in length over time under normal circumstances as cells make copies of themselves, thereby leading to a point where the cell can no longer divide. Therefore, it is suggested that stress thus decreases life expectancy.
Fortunately, though, the changes that occur in both the telomeres and the mitochondrial DNA, are mostly reversible: when the mice were freed from stress, their DNA recovered.
Now, how is stress-related depression linked with molecular changes in the body? Stress itself is caused by a number of factors, including lack of food, and environmental ones. Consequently, stress impacts negatively on the efficiency of mitochondria. The body is thus stimulated to create more to protect itself. It is also suggested that thus is depression the response of the body to environmental stress.
This study might be indicating possible treatment for depression in the future. The molecular changes being reversible, treatment at the molecular level may be assessed as to its potential success.