Young people in custody often suffer from brain development disorders, according to a newly-published report.
Experts have carried out a review of published evidence which shows youngsters who have been in trouble with the law tend to have more neurodevelopmental problems than the wider population.
Researchers from the universities of Birmingham and Exeter found that young offenders were four times more likely to have a specific reading difficulty - around 43% to 57% compared to 10% of the wider population.
Many of the youngsters have a reading age below that of criminal responsibility, which is 10 in England and Wales.
The vast majority of young offenders (60% to 90%) have speech and language difficulties and a quarter may have a learning disability.
Up to three in four young people who commit crimes suffer from the effects of a traumatic brain injury, such as from a direct blow to the head, penetration of the skull or traffic collision. This compares to fewer than one in four of the general population.
The review was carried out for the Office of the Children's Commissioner (OCC), which called for earlier recognition of, and vital improvements in, the treatment and support of young people with brain conditions.
The OCC's report - Nobody made the connection: The prevalence of neurodisability in young people who offend - draws attention to the large numbers of young people in children's prisons in England who have neurodevelopmental difficulties, such as brain injuries, that could result in communication difficulties, cognitive delays, learning difficulties and emotional and behavioural problems.
Maggie Atkinson, Children's Commissioner for England, said: "This report raises serious questions about whether significant numbers of children in the youth justice system have the ability to understand the whole process from arrest through to sentencing.
"Our failure to identify neurodevelopmental disorders and put in place measures to prevent young people with such conditions from offending is a tragedy.
"It affects the victims of their crimes, the children themselves, their families, the services seeking to change offenders' lives for the better, and wider society.
"Although children who have neurodevelopmental disorders and/or who have suffered brain injuries may know the difference between right and wrong, they may not understand the consequences of their actions, the processes they then go through in courts or custody, nor have the means to address their behaviour to avoid reoffending."
One of the research authors for the report, Dr Nathan Hughes, director of education and senior lecturer in social policy and social work at the University of Birmingham, said: "This report consistently demonstrates a youth justice system that continues to punish young people for the risks and vulnerabilities associated with their neurodevelopmental difficulties.
"However, it also offers grounds for optimism in the future development of services and support based on our improved understandings of neurodisability."
The Children's Commissioner makes recommendations for the government, local strategic partnerships, the judiciary, clinical commissioning groups, and managers and practitioners across the youth justice system.
She calls on them to make sure neurodevelopmental conditions are more rapidly identified in children and young people and that they receive better and faster treatment.