Cantabrians who lived through the quakes of the past decade might have been affected in more ways than they realise, with preliminary research indicating the trauma may have led to subtle brain changes.

Studies have already pointed to significantly higher levels of depression, acute stress and anxiety among those Christchurch residents who were living in the worst-affected areas.

Now, researchers part-way through a two-year study are investigating whether the quakes affected the way people process fear in their brains, despite not having any diagnosed psychological issues such as Post Traumatic Stress Disorder (PTSD).

The research team suspect that brain changes - both in structure and how information is processed – may have taken place, as happened among those who lived through the 9/11 terrorist attacks in the US.

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Dr Nadia Borlase, a research associate at the NZ Brain Research Institute, said that since the earthquakes, the number of people in Christchurch with mental health difficulties has steadily increased and other issues may arise over time.

"There is very little research on a population who have experienced something like the Canterbury Earthquakes but who haven't gone on to develop any psychological diagnoses, such as PTSD," Borlase said.

"We are interested in the long term effects of this experience of the earthquakes in people that don't have any clinically significant psychological problems."

The study was drawing on a group of people already taking part in a wider ongoing study, run by Otago University's Department of Psychological Medicine.

About 60 Christchurch people had completed brain scans – which involve a series of disturbing and "neutral" pictures being shown to tease out any effect - which would be eventually compared with those of Dunedin people being recruited for a control group.

The research would help researchers understand the long-term effects of trauma exposure on the brain in resilient people, she said.

"We know trauma exposure, like that from the earthquakes, can have long-lasting effects such as cognitive decline, cardiovascular problems and decreased life expectancy," she says.

The control group, used in the research, experienced significant personal loss during the earthquakes of 2010 and 2011 but don't have PTSD or other psychiatric disorders.

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Their experiences include physical injury or illness, seeing buildings fall, witnessing death or loss of income or property.

"Our research is indicating trauma from the earthquake is still likely to have an impact on the brain, which could lead to other effects in their lifetimes."

Borlase said that such "sub-clinical symptomatology" was not routinely screened for, and difficult to detect.

"We aim to use the proposed research to add neurological knowledge and assist in detection and monitoring of the outcomes of trauma exposure in otherwise healthy individuals," she said.

"Findings from this research should also be applicable to other cohorts exposed to trauma, such as war, terrorist attacks or natural disasters."

This research – jointly being carried out by NZ Brain Research Institute and Otago University's Department of Psychological Medicine – is funded by The Neurological Foundation and will be completed by June next year.

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*Dunedin residents interested in taking part in the research can contact Dr Nadia Borlase at nadia.borlase@nzbri.org.