"This is good news as it offers preliminary evidence that there are no long-lasting effects on cognitive impairment after exposure to a traumatic event, at least in people who don't develop a mental health condition.
"It suggests changes in their cognitive functioning and emotion processing may be related to exposure to continued threat in the environment, which improves when the threat resolves,' she said.
Douglas said the findings back up similar international studies which show the brain's ability to recover once distanced in time from the original trauma.
"When the original studies were conducted, people were living in an environment of ongoing seismic activity where, over a two-year period, Canterbury experienced over ten thousand aftershocks.
"The fact that residents were in a chronically hyper-aroused state may have resulted in biological changes in the brain, such as in the amygdala, which is responsible for processing strong emotions. By the time of the current study however, there was no seismic activity and the sense of threat had abated."
Study co-author, Associate Professor Caroline Bell, also from the University of Otago, Christchurch, says the study adds to the growing body of international research relating to how large groups in society react and respond following traumatic situations.
"These findings give us a sense of the effects of exposure to major threats from disasters such as earthquakes on wider populations.
"They are reassuring in showing that a resilient response is the most prevalent. They also suggest, conversely, that persisting impairments in threat sensitivity and cognitive functioning may affect people's productivity and could potentially be a target for intervention," she said.
