A new study has shown the compounding risks for young people in trouble with the law.

Drugs, sex, illness and abuse are rampant throughout the key section of society, and must be tackled with a multi-faceted approach, researchers say.

Young people serving time in youth detention or serving community-based orders have extremely high rates of substance dependence, poor mental health and engage in risky sexual behaviour, researchers from Murdoch Childrens Research Institute and the University of Melbourne have found.

The recent study interviewed over 500 young people in custody or community-based orders about their educational and vocational experiences, violence and sexual assault, offence history, family history of mental illness and imprisonment, and their substance use and own mental health.

Among the concerning statistics is the finding that 34 per cent of those serving community based orders and 66 per cent in youth detention were dependent on alcohol, cannabis, heroin, amphetamines or sedatives – the most common being cannabis.

Young people in youth detention are significantly more likely to have ever injected a drug (48 per cent compared with 13 per cent). Rates of hazardous alcohol use were found to be high in both groups: 73 per cent for young people serving community based orders and 82 per cent for those in custody.

Depression was common in both groups, with many reporting engaging in self-harm.

In both groups, 29 per cent reported having a family member with a history of mental illness. The majority reported having sex before 15 years of age, and one in ten reported having had more than five sexual partners in the past six months.

“The links between substance use, poorly managed mental illness and offending are well documented. Addressing the complex health needs of these young people therefore has the potential to not only improve their future, but also reduce the risk of reoffending – it’s a win-win situation,” said lead author Associate Professor Stuart Kinner.

“Young people in juvenile detention have disastrous health profile that costs them dearly in premature death and disability and the community in their reoffending,” said senior author Professor George Patton.

“The health problems of young offenders are inseparable from their offending. These young people become caught in a vicious cycle in which substance abuse and mental disorders contribute directly and indirectly to their offending.

“There is a compelling case for investment in both health and vocational training of these young people as they enter the justice system and crucially, as they return to the community,” he said.

“Recent innovations in monitoring the health of adult offenders should be extended to young offenders - including those serving community based orders - where the best opportunities for early intervention lie.”

More information is available in the full report.