Children and young men are suffering more head injuries than anyone else, many caused by falls, knocks in rugby and car accidents, according to research.
Traumatic brain injuries remain at epidemic levels with a head injury occurring in New Zealand every 15 minutes, a study into the long-term effects shows.
The $2.3 million BIONIC4you study by Auckland University of Technology and the University of Waikato identified 1069 victims of head injury in the Waikato in 2010 and, with another $1 million in funding from the Health Research Council, researchers have caught up with 628 of the sufferers.
University of Waikato Associate Professor in the School of Psychology Dr Nicola Starkey said children made up a third of the original sample of victims.
The greatest number of head injuries for children playing sport was through cycling, rugby, soccer and swimming.
Rugby, equestrian, motocross and cycling were the sports causing the most head injuries in adults but Dr Starkey pointed out rugby was also one of the most popular sports.
Dr Starkey said many people were not aware that a mild traumatic brain injury could lead to ongoing problems and many did not link those daily symptoms, affecting their physical, cognitive, social, emotional and behavioural wellbeing, with the original head injury.
Up to 30 per cent of adult victims develop post-concussive syndrome, which can last years after the accident and include difficulty concentrating, fatigue, headaches, mood swings and lethargy.
Dr Starkey said one of the reasons for the long-term study was to find out how to treat patients to avoid lasting damage such as post traumatic stress disorder (PTSD).
Those most vulnerable to developing PTSD were women who had been assaulted, where the traumatic event triggered a pre-existing condition such as anxiety or depression.
The study is being led by the National Institute for Stroke and Applied Neurosciences (Nisan) director, Professor Valery Feigin, with help from Dr Starkey and Nisan neuropsychologist Dr Kelly Jones.
Long, hard trip back for athlete
Stefan Hadfield has a slight dent on the left side of his head where his temple is missing.
It's the only physical clue to the 2007 skiing accident in Canada that left him critically injured in an induced coma with a severe traumatic brain injury.
The Hamilton extreme athlete, who has represented New Zealand in X Games and set world records in rock climbing, had to rebuild his life, learning to walk, talk and eat all over again.
He had several risky operations to insert a plastic skull after the drop on to a rock from a 12-metre cliff at Whistler fractured the bones in his head and caused the brain injury.
The 194cm-tall 24-year-old, who had been in training to journey from the North to South Pole, went from 84kg to 67kg. When he woke he had no memory of the accident and even now can only just remember arriving back in New Zealand nine weeks later.
"I didn't know who I was, where I was or who my family were."
Though he could muster only a few words in some of the 13 languages he once knew, Mr Hadfield was able to play a guitar three weeks after waking up and said music was a big help in his recovery.
Now 31, he said that while another serious blow to the head could kill him, his only physical limitation is a peripheral vision impairment.