Brain-injured offenders are packing Kiwi prisons, leaving experts calling for better assessment and rehabilitation of those suffering head injuries.

Ministry of Health figures show 64 per cent of prisoners have suffered a traumatic brain injury (TBI), compared with just 2 per cent of the general population.

Studies put the number even higher, with 80 per cent of non-Maori and 90 per cent of Maori prisoners suffering from TBI.

Neurologist Richard Seemann said it was "a given" brain injury was linked to offending behaviour.

Seemann said the frontal lobes of the brain were "the part in charge of putting brakes on behaviour - so, you think a thought but don't say it out loud, or think about doing something but decide not to do it".

People with frontal lobe injuries had trouble recognising consequences, resisting impulses, or discerning appropriate behaviour - tendencies that could land them in trouble with police, he said.

Max Cavit, manager of brain-injury support provider ABI Rehabilitation, said while many people with brain injuries would never offend, some developed behavioural issues that landed them in court.

Common effects of brain injury such as sexual disinhibition, poor risk judgment, difficulty empathising and anger-management issues were also associated with offending.

"We've had a one man who had no history of sexual offending ... who after a severe brain injury ... ended up in the prison system," Cavit said.

Another client, following a gunshot wound to the head, "developed a liking for drinking and jumping into stolen cars".

A 2012 study by University of Canterbury Professor Randolph Grace found children who experienced head injuries were more likely to offend as adults.

Experts say proper recognition and rehabilitation of brain injuries would help people to manage their behaviour, and could help stem the tide of offending.

Cavit said rehabilitation was needed for those with brain injuries to develop strategies to manage symptoms.

"We tend to think, 'Just get over it, just control that behaviour', but it's like asking someone who's lost an eye or an arm to just use that arm or see out of that eye."

Treatment in the justice system worked to reduce reoffending, and programmes to track and manage brain injury in Australian prisons had seen recidivism drop by 20 per cent, Cavit said.

He urged New Zealand prisons to consider adopting something similar.

"All the places in the world that have done this, have seen it work. The fact that it works is not in dispute. It's just how to implement it."

Corrections offender health director Bronwyn Donaldson said prisons did not screen for historic brain injuries when prisoners arrived, but if staff had concerns about a prisoner's cognitive functioning, appropriate screening could be organised.