In order to inform its development of a guideline on sentencing young people, the council asked the University of Edinburgh to carry out a systematic review of the current neurological, neuropsychological, and psychological evidence on the cognitive maturity of younger people.

The review findings confirm that the adolescent brain continues to develop into adulthood and does not reach full maturity until approximately 25-30 years of age.

The review, understood to be the first of its kind in the Scottish context, found that the areas of the brain governing emotion develop sooner than those which assist with cognitive abilities and self-control. This imbalance explains the increased risk-taking and emotionally driven behaviour commonly attributed to young people.

Furthermore, brain development may be delayed or hindered by other factors such as mental disorders and distress, adverse childhood experiences, traumatic brain injury (TBI), and alcohol and substance use. These contextual risks therefore introduce significant vulnerability in young people. The very nature of brain development during the transition to adulthood is often at the root of the risk-taking behaviour which can cause further damage to the already vulnerable younger brain.

The review highlights a ‘well-established correlation’ between TBI and antisocial behaviour and violent offending. In particular, it finds that a TBI suffered during adolescence can be more damaging as it interrupts the development of the brain.

All of this means that the younger brain is less well-equipped to enable good life choices and exert self-control, and is disproportionately vulnerable to the factors which can compound these problems.

As the brain continues to develop during our late teens and into our twenties, and in light of these wider findings, the research finds that there is a strong case for considering cognitive maturity in judicial decision-making up to at least age 25.

Sheriff Principal Ian Abercrombie QC, chair of the Scottish Sentencing Council’s Sentencing Young People Committee, said: “This is a highly significant piece of research and we would like to express our gratitude to the University of Edinburgh for carrying out this work.

“The point at which the brain is fully developed and people are able to better regulate their behaviour is an important consideration for sentencing as it relates to the level of culpability, or blame, for the offence in question.

“It has been well established practice in Scottish courts that young people are not deemed as culpable for their offending behaviour as adults are. This research will no doubt add to the debate around how the criminal justice system in Scotland deals with young people who offend.”

The Scottish Sentencing Council will shortly launch a 12-week public consultation on its draft guideline for sentencing young people.