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The neuroscience of crime: will a new brain study enhance the rights of young offenders?

Crime may be more tied to biology than we realised. This is the contentious finding of a major Lancet Psychiatry study, published last month. Researchers identified a difference in brain structure among individuals who had engaged in a lifetime of criminal behaviour.

A study with such far-reaching implications raises many questions. How can we determine its accuracy and separate cause from correlation? Additionally, how might these findings impact the human rights of offenders? Study authors have cited hopes that it will encourage a “compassionate” approach to young offending, favouring early intervention and increased social support. But oversimplified interpretations of biological ‘weakness’ could have detrimental effects.

Teenagers are overwhelmingly the perpetrators of crime. The much-cited age-crime curve shows that, in the majority of cases, criminality doesn’t persist into adulthood.

It’s important to clarify this study uses the term ‘criminal’ behaviour to refer to acts of delinquency such as stealing and violence, regardless of whether they have resulted in prosecution. Even adopting this broader definition, those who continue to engage in criminal behaviour throughout their lives remain a minority group. The study results are especially illuminating with regards to this minority group.

Researchers used MRI scans to analyse the brains of 672 New Zealand-based participants, all aged 45. The cohort, tracked since early childhood, was considered population-representative, taking socioeconomic disparities into account. 151 of the participants had only engaged in criminal behaviour as teenagers. No widespread brain abnormalities were identified within this group.

But a different pattern emerged when researchers turned their attention to the 80 individuals, whose criminal behaviour had persisted throughout their lives. They identified a notable difference in their brain structure: a reduced mean average surface area and thinner brain cortex in key regions of the brain – regions thought to regulate emotions, motivation and goal-directed behaviour.

How can we distinguish between these different types of ‘offenders’ when they are still young? Researchers are not suggesting we conduct brain scans on every misbehaving teenager. But the age at which conduct problems arise is an indication. Among ‘lifelong offenders,’ they tend to appear sooner – in early childhood.

Dr Essi Viding, professor of Developmental Psychopathology at UCL, is co-author of the study. She believes these children need additional support at the earliest possible opportunity to prevent their behaviour from escalating. Currently, they are “being failed by society”. Long-term offenders often show a tendency towards violence from a young age, she notes. This makes them prime targets for policies such as school exclusions. But this cohort needs “additional help, not social isolation or demonisation”, Dr Viding argues. “They are operating under some handicap at the level of the brain”.

It’s important to make a distinction here. A “handicap at the level of the brain” refers to a biological susceptibility. But criminal behaviour cannot be grounded in genetics alone.

Painting them as victims of biology could be detrimental to the rights of offenders. It implies certain offenders are ‘a lost cause’. And it distracts from social factors.

Many of the study’s lifelong offenders come from challenging home environments, facing multiple social challenges in addition to the biological. It’s impossible to disentangle genetics from environmental influences. But highlighting a biological vulnerability shouldn’t undermine the importance of tackling the latter. On the contrary, it is crucial to address social factors since these are the ones that can be altered.

The interwoven nature of genetics and environmental factors does create a study limitation: we cannot fully separate cause and effect. This is the first study to use neuroimaging and “the largest and most persuasive so far (in demonstrating biological difference)”, says Professor Stein, from the Institute of Food, Brain and Behaviour. “But it still leaves a burning question unsettled. What causes the (brain) reduction?”

Since the brain scans were performed on 45 year-olds, we cannot be sure when the alteration occurred. It may have been present from birth, contributing to disruptive behaviour. But it’s possible that a lifetime of mental ill-health and drug abuse –prevalent among the group of lifelong offenders- caused this brain abnormality to develop.

It’s equally crucial to take traumatic brain injury into account. A growing body of research shows that prisoners experience early-life head injury at much higher rates than the rest of the population. In 2015, The Disabilities Trust screened 613 men upon admission to Leeds Prison. 47% had experienced at least one traumatic brain injury prior to conviction. There is substantial scientific evidence showing severe head injuries can lead to aggressive behaviour and poor impulse control.

With all these factors at play, the study-in-question requires further research -something its authors are well aware of. At a Wellcome Trust briefing, they made a plea to avoid oversimplified interpretations: “the findings do not mean that all offenders have small brains”.

Leaning on biology to explain crime poses a risk of undermining social factors, as discussed. But how might this study help to advance a human rights agenda?

A key finding is the young age at which patterns of disruptive behaviour emerged in those -with a suspected biological vulnerability- who went on to become lifelong offenders. It supports the case for early intervention, to protect this group from policies leaving them vulnerable to incarceration. School exclusions, for instance, and the sense of hopelessness they instil, pave the way to criminality. The number of permanent school exclusions has reached its highest point in nearly a decade in England.

Additionally, the findings call for scrutiny of the age of criminal responsibility in the UK. Excluding Scotland, in the UK children as young as 10 can be prosecuted and given a criminal record. This is the lowest minimum age in any EU state – the average being 15.

The system of juvenile justice in the United Kingdom is “excessively punitive”, says Thomas Hammarberg, former Council of Europe Commissioner for Human Rights.

The number of children in custody has fallen in recent years – a step in the right direction. But the UK has repeatedly resisted pressure from the UN’s Committee on the Rights of the Child to raise the age to 12 at the absolute minimum.

Criminalising children adversely affects their future prospects and may increase the likelihood of them reoffending as adults. And indeed, the study in question found a correlation between early-onset behavioural difficulties and lifelong offending.

“The Lancet study is yet another reminder of the manifold and complex reasons a young person can end up in detention. While human rights must be protected for everyone in detention, hopefully these findings will better result in care and support for those who have underlying neuropsychological differences.”

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