What doesn’t kill you makes you stronger? Genes determine the long-term effects of stress
For some people, no strain means no gain. They seem to come out of every crisis a stronger person, with renewed insight and energy. Others, however, bear the emotional scars of their traumatic experiences for years.
A study by researchers at the Medical University of Vienna has shed new light on why there is no one-size-fits-all outcome of stressful experiences. Their findings show that similar life events have very different effects on our brains depending on three specific genetic variants that have previously been linked to depression.
These gene variants determine the long-term effects of our ordeals by modifying the reaction of the hippocampus to stress. The hippocampus is an area of the brain described as the “central stress interface”. It changes in size depending on the degree and quality of the pressure you're under. When you’re faced with a perceived threat to your safety, it shrinks, whereas the type of stress you may experience in exciting social situations can actually make it grow larger.
In those suffering from depression and post-traumatic stress, the hippocampus is often found to be smaller than average, a finding to which many of the symptoms of these disorders have been attributed.
In order to examine the interaction between stress, genes and hippocampal size, the researchers gathered information on the life events of 153 healthy subjects, as well as carrying out MRI scans and DNA extractions. Their results showed a clear interplay between stress and the three risk-factor genes.
"People with the three gene versions believed to encourage depression had a smaller hippocampus than those with fewer or none of these gene versions, even though they had the same number of stressful life events," explains study leader Lukas Pezawas.
On the other hand, those who had only one or none of the gene variants studied, showed the opposite reaction to stress: Their hippocampi were enlarged after experiencing comparable burdens.
These findings indicate that to a large extent, our genes dictate whether stressful events will ultimately build us up or bring us down.
"These results are important for understanding neurobiological processes in stress-associated illnesses such as depression or post-traumatic stress disorder. It is ultimately our genes that determine whether stress makes us psychologically unwell or whether it encourages our mental health," according to Mr Pezawas.
If this all sounds a little too fatalistic to you, don't be alarmed. Previous research has shown that our mindsets also moderate the effect that stress has on us, and that we are able to change those beliefs in order to increase our resilience. Understanding the way you naturally respond to stress is key to developing better coping strategies that work for you.