Auckland, New Zealand – Traumatic brain injuries may be more common than previously thought, suggesting they have not been properly accounted for throughout the world, finds a new study from Auckland University of Technology.

Researchers examined more than 173,000 TBI cases in New Zealand from 2010 to 2011 and found the rate was higher there than in other developed countries – 790 per 100,000 people a year in New Zealand, compared with 618 per 100,000 in North America and 453 cases per 100,000 in Europe. By their estimate, 2.2-3.36 million people worldwide suffer moderate to severe TBIs per year, which is nearly 6 times higher than previous estimates, according to an AUT press release.

Mild TBIs, which accounted for 95 percent of cases in the study, can result in memory loss, seizures and depression.

Among New Zealanders, falls were the main cause of TBIs (37.7 percent), followed by mechanical forces (21 percent), transport incidents (20.2 percent) and assaults (16.7 percent). Children, young adults and rural residents were among the most at risk for TBIs, according to the study abstract.

The study was published online Nov. 22 in The Lancet.