Stress is to blame for a spike in the number of strokes after the Christchurch terror attacks, a study has found.
New research, led by Canterbury District Health Board neurologist Dr Teddy Wu in collaboration with the New Zealand Brain Research Institute, shows there were four times as many acute strokes in the city the week after the mosque attacks and more than four times the number of large strokes.
Dr Wu said the surge in stroke hospitalisations was only found in Christchurch.
He said it is likely stress around the attacks increased the risk of blood clotting leading to more strokes.
"The statistics suggest the observations of increased treatments and large strokes in Christchurch did not occur by chance.
"The most plausible explanation is the generalised stress response after the terror attack. This may increase risk of blood clotting."
Professor Tim Anderson, clinical director of the NZBRI, said the study has been hailed internationally as an exceptional and important piece of work.
"It shows a clear relationship between stress and acute and large strokes. There has never been clinical evidence of this before.
"Worldwide, post-9/11 New York researchers focused on heart failure, and Japanese researchers reported an increased number of strokes throughout Japan at the time of the earthquake/tsunami in 2011, but in terms of having information about the size of the strokes, our study is unique," he says.
Three days after the terror attack, the NZBRI team set out to see if there was an increase in strokes in the city.