Our brain’s reaction to pictures of angry or fearful faces could help predict our risk of developing depression or anxiety in response to stressful life events, a new study suggests. Researchers used MRI scans to examine activity levels in a part of the brain associated with our fear response — called the amygdala — when 340 healthy young students were shown images of angry or fearful faces. The students were then contacted online regularly for at least the next year to report on their mood and any stressful experiences. According to results published today in Neuron , the students who showed greater brain activity in response to the images also showed a greater vulnerability to psychological stress brought on by events such as the death of a friend, a parent losing a job, or being in a car accident. Lead author Dr Johnna Swartz, a post-doctoral associate at Duke University says the findings could help improve our ability to identify people most at risk of these mental illnesses. “We’re just not very good at predicting who’s going to develop depression and anxiety,” Swartz says. “We know some of the major risk factors; we know for example that childhood maltreatment, having a family history of the disorder and stressful life events are risk factors, and many people experience these but only a subset go on to develop the disorder.”
The amygdala plays a key role in processing emotions, particularly fear in response to perceived threat. Previous studies have shown that this region is hyperactive in individuals with depression and anxiety, but what’s not known is whether this hyperactivity is a side effect of these disorders, or if it’s something that exists before these disorders developed and perhaps even predisposes people to developing them. Swartz and colleagues’ results suggest that amygdala reactivity is around long before people develop mental health issues. “The fact that we could see this relationship as much as one, two, or three years out was surprising because quite a bit happens in that amount of time, and it’s just one measure of brain function at one time point.” The challenge now is to work out how amygdala reactivity might be used to predict risk of future mental health symptoms. The researchers are looking at the genes linked to amygdala function in the hope that genetic testing might offer a way to find higher risk people. “It’s much cheaper to get a saliva sample and look at somebody’s DNA than to run an fMRI scan,” Swartz says. “If we know that amygdala reactivity predicts [depressive] symptoms then we can essentially use the genes as markers of risk and that would be a relatively cheap way to assess people’s risk.”
This article first appeared ABC, 5 February 2015.