By Ben Beaglehole & Joseph Boden

Cantabrians have endured much hardship over the last decade. First, a series of earthquakes, and more recently, the massacres at two mosques in the city on March 15 this year. The Canterbury earthquakes began with a 7.1 magnitude earthquake on 4 September 2010 and continued for an extended period with further major earthquakes in February, June and December 2011, and more than 10,000 aftershocks. The February 2011 earthquake was particularly devastating for the people of Canterbury, resulting in significant loss of life, multiple injuries, and widespread damage to property and infrastructure.

Media reporting following the Canterbury earthquakes suggested widespread suffering and adverse effects on mental health. In the years following the earthquakes, there were even suggestions that children in Canterbury had become “neurologically different” due to their exposure to the earthquake sequence (5). However, the extent of adverse effects reported by the media and by some researchers did not match our own clinical and research experiences. It seemed likely that media relied on health statistics and isolated studies that were subject to methodological problems in forming their view.

In order to better understand the actual magnitude of the effects of the earthquakes on the mental health of Cantabrians, we undertook a systematic review of all published studies that had measured psychological distress or mental illness following the Canterbury earthquakes.

A systematic review

In undertaking this review, we used a well-established set of techniques for conducting systematic reviews. Relevant papers were identified using a comprehensive screening process and a quality analysis of included studies was completed, using agreed-upon quality guidelines. A number of papers, including some written by our research group, reported different outcomes for the same study population. In total, we identified 20 single and combined studies evaluating psychological distress or mental disorder following the earthquakes. Two studies were identified that evaluated mental health outcomes for children and one study reported effects for older adults.

Our main finding was that of widespread but not universal adverse effects of the earthquakes on the people of Canterbury. Adverse effects were measured by studies in a number of ways. These included psychological rating scales, tracking psychiatric medication use, and diagnostic tools for depression and anxiety disorders. Although some studies did not report negative consequences following the earthquakes, the majority of studies reported worsening mental health. Study findings included higher post-traumatic stress scores, higher rates of overall mental disorder, worse scores on mental health rating scales, short term increases in prescribing of sedatives, and higher rates of mood and anxiety disorders.

It was important to clarify the magnitude as well as the presence of adverse effects. There were substantial differences in timing, sampling, and outcome measurement between the studies included in the review. This meant we could not use the data combination technique of meta-analysis to derive an overall estimate of the impact of the Canterbury earthquakes on mental health. However, the extent of adverse effects reported by most studies was small.

One of the two studies evaluating the impacts on children reported adverse effects. This was a school-based study measuring post-traumatic symptoms in children attending selected schools. A much larger study evaluating emotional and behavioural scores from a universal before-school check did not detect any evidence for negative consequences following the earthquakes.

The only study focusing on older adults did not report significant differences between those exposed to the earthquakes and those not. However, the relative absence of studies evaluating the impact of the earthquakes on children and older adults meant it was unclear whether these populations behaved similarly or had unique effects. In addition, the majority of studies were completed less than two years following the onset of the earthquake sequence meaning little is known about delayed or persistent responses and whether initial effects have decreased over time.

What are the implications of these findings?

We found widespread but not universal adverse effects on mental health as a consequence of the Canterbury earthquakes. The adverse effects were mostly small and did not match reporting by media which painted a picture of marked and widespread morbidity as a result of the earthquakes. It is likely that the view formed by media arose from focussing on the findings of single studies and local health statistics that did not take into account trends occurring nationally that were unrelated to the earthquake sequence (mental health services up and down the country are reporting increased demand for care possibly driven by population increases and other societal factors such as methamphetamine use).

A number of strategies were present in Canterbury to mitigate adverse effects after the earthquakes. These included access to free counseling, extended general practitioner consultations and other health-promoting community initiatives. To a large degree, public and private insurance also served to repair earthquake damaged homes and infrastructure. It is not possible to know the impact of these initiatives but we presume that the magnitude of adverse effects would be greater in their absence.

Although we have identified adverse effects as a result of the earthquakes, a growing body of literature also reports the potential for post-traumatic growth following individual and collective adversity. This possibility should not be discounted in the Canterbury setting. Although studied to a lesser degree, researchers have reported positive consequences and growth in personal relationships following the Canterbury earthquakes.

Are there any lessons from the Canterbury earthquakes that hold relevance now that the community is also dealing with the aftermath of the Canterbury shootings? It seems inevitable that an increase in psychological distress and mental illness will occur for some. It is likely that those with the greatest degree of exposure to the shootings will be most affected. This means that special interest and care should be given to those present in the mosques, and to first responders. Similar initiatives to mitigate adverse effects to those used previously should be introduced. These should be complemented by strategies addressing the unique experiences faced by Muslims living in Christchurch (the government should be applauded for their compassionate decisions providing certainty of immigration status). Finally, not all people exposed to the shootings will experience serious adverse effects and the possibility of post-traumatic growth should not be discounted for some.

Ben Beaglehole is a Senior Lecturer at the Department of Psychological Medicine, University of Otago, and an inpatient psychiatrist at Hillmorton Hospital. 

Joseph Boden is an Associate Professor at the Department of Psychological Medicine, University of Otago, and part of the Christchurch Health and Development Study. 

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