House landing on overturned truck - Hurricane Katrina (Shutterstock)

In the aftermath of a natural disaster, could observing something as simple as pupil dilation indicate which of the survivors will be slammed with depression?

Research at Binghamton University in the wake of a recent local disaster in Upstate New York indicates pupil response is indeed a predictor of depression risk, as reported in the journal Clinical Psychological Science.

Such a biomarker could better direct mental health resources in the wake of the physical damage and mental stress, they conclude. 

“In light of the current findings, it is certainly plausible that individuals displaying deceased pupillary response to emotional stimuli and relatively higher levels of disaster-related stress may be good candidates for cognitive therapy to alleviate their depression,” said Brandon Gibb, one of the authors, who is also director of Binghamton’s Mood Disorders Institute.

The psychologists assessed 51 women who were impacted by a major 2011 flood in the Binghamton area. The group was split into those who had previously been diagnosed with a mental disorder, and others who had never been diagnosed with a mood disorder classified in the DSM-IV.

Both groups were presented with emotional facial expressions of people on a screen, while their pupils were monitored.

“Decreased pupil dilation to emotional expressions predicted a significant increase in post-flood depressive symptoms, but only among women who experienced higher levels of flood-related stress,” they conclude.

Decreased pupil dilation has previously been linked to emotional response strategies such as suppression, according to the study. The smaller pupils also is asosicated with decreased activity in the brain's dorsolateral prefrontal regions - which are associated with a hindered ability to effectively regulate emotions and executive control.

As many as 25 percent of people impacted by natural disasters can develop depression, said Mary Woody, a Binghamton graduate student who was the lead author of the study. By using a new method to identify those most at risk, and get them help as soon as possible, could help mental recoveries – and even save precious resources in disaster areas.

“One of the theories of depression is that there’s a lot of vulnerabilities for depression that lay latent until stress activates them,” said Woody. “Our idea was to look at a vulnerability factor/risk factor pupil response and see if we could predict which families have the most depression following the flood if they had more of this particular risk factor.”

The Binghamton flood was due to Tropical Storm Lee that led to record-high floodwaters, the evacuation of 22,000 residents, and an estimated $513 million in property damages.

Post-traumatic stress disorder has shown to manifest itself physically in the brain and elsewhere – even showing up in epigenetic changes to DNA which have shown up in the offspring of Holocaust survivors.