People who suffer a traumatic brain injury as a child are more likely to commit offenses as adults, researchers say.
Professor Randolph Grace of the University of Canterbury, and Dr Audrey McKinlay from Melbourne's Monash University, studied Canterbury children who had experienced a brain injury as a child from birth to 17 years old.
The participants were now 18 years or older and more than five years had passed since their injury.
A traumatic brain injury is caused by an external force, such as a bump or blow to the head, which disrupts the normal function of the brain. The effects range from mild memory difficulties to dementia, seizures and depression.
The researchers looked at participants' lifetime involvement in offending behaviour, and also assessed the participants on emotional behaviour, looking at malevolent aggression, social anxiety and social self-esteem.
Dr Grace said there is "increasing evidence" childhood TPI can have negative impacts during adulthood.
"We found TBI was significantly associated with an increased risk of offending behaviour. Our analysis revealed that for people with moderate to severe TBI the strongest predictors of offending behaviour was the TBI status - higher levels of malevolent aggression and lower levels of social anxiety.
"This research has made a major contribution to reducing offending behaviour for individuals with TBI by identifying measures of emotional behaviour as useful predictors of offending behaviour and offer an opportunity for early intervention."
According to recent research, about 36,000 new TBI occur every year in New Zealand, far surpassing the number of heart attacks and more than five times the number of new strokes, Dr Grace said.
Most of the injuries were due to falls (38 per cent), followed by mechanical forces, transport accidents and assaults.