Incarcerated young people have high rates of neurodevelopmental disorders. A recent international review of research found estimates of the rate of learning disability among young people in custody range from 23% to 32%, compared to 2-4% among the general population.

Similarly, 60-90% of young people in custody have been assessed as having a communication disorder, compared to 5-7% of all young people.

The same patterns exist for attention deficit hyperactivity disorder (ADHD) and autism. What’s more, these are likely to be underestimates of levels of need. Many young people in custody are affected by particular symptoms or sub-clinical levels of impairment.

Clearly, to reduce the numbers in custody, we need to understand how a broad range of disorders affects them.

Childhood neurodevelopmental impairments are physical, mental or sensory functional difficulties caused by disruption in the development of the brain or the rest of the nervous system. They are typically the result of a complex mix of influences. These include: genetics; pre-birth or birth trauma; infection, illness or injury in childhood; or nutritional, educational or emotional deprivation.

The resulting difficulties include cognitive deficits, specific learning difficulties, communication difficulties, and emotional and behavioural problems. These are commonly experienced as one or more clinically defined disorders, such as intellectual or learning disability, specific learning disorders, communication disorders, ADHD, and autism.

So how might increased rates of custodial intervention be explained? At least three sets of explanations need to be considered.

Cognitive or emotional deficits lead to antisocial behaviour

Neuroscience offers various explanations as to how cognitive and emotional traits that are symptomatic of neurodevelopmental impairment can give rise to aggressive or antisocial behaviour. This, in turn, increases vulnerability to criminality. For example:

• ADHD is characterised by various behavioural symptoms, including inattentiveness, hyperactivity and impulsivity. The latter is particularly implicated in antisocial behaviour through a “de-coupling” of cognition and emotion. This can result in impatience, sensation-seeking and difficulties in restraining emotional reactions. That increases the likelihood of impulsive acts, particularly in response to provocation or conflict.

A complex mix of influences on a child can lead to neurodevelopmental impairment.shutterstock, CC BY-NC

• Deficits in executive functioning are seen in a range of neurodevelopmental disorders. Executive functioning is an umbrella term to describe the cognitive processes used to undertake complex goal-oriented thought and action. It includes the initiation, planning and sequencing of tasks, concentration and the self-regulation of contextually appropriate behaviour. Deficits in such functions influence antisocial behaviour by reducing inhibition or impairing the ability to anticipate consequences.

• Communication impairments are linked with a range of neurodevelopmental disorders. A reduced capacity for effective social interaction can affect the selection of language and/or non-verbal communication appropriate to the social context. Poor social communication may also result in difficulties understanding and expressing emotions, or challenging behaviour as a means to communicate feelings.

Increased exposure to social and environmental risk

Clearly, neurodevelopmental impairment may increase susceptibility to a range of negative social experiences that heighten risk of criminality. These include negative peer group influences; problematic parenting practices; and educational disengagement.

Neurodevelopmental impairment can influence ‘school readiness’.shutterstock, CC BY-NC

• Deficits in social communication can affect peer relationships, leading to a heightened desire to be accepted. Young people with speech and language difficulties are approximately three times more likely to be “regular targets for victimisation” than young people in general. Similar findings have been made for young people with ADHD or a learning disability.

• Parenting a child with a neurodevelopmental disorder can involve a range of challenges, particularly when it is undiagnosed or adequate support is lacking. This can inadvertently lead to parenting practices – such as less positive parenting or ineffective discipline – that increase the risk of problematic behaviour.

• A potential association between early difficulties in engaging with education due to impairment and subsequent classroom misbehaviour is also apparent. Neurodevelopmental impairment can affect “school readiness”. For example, ADHD symptoms of hyperactivity and poor capacity for attention can inhibit early school engagement.

Difficulties in pre-school and early educational experiences have a cumulative effect. Difficulties prior to the age of eight lead to challenges in engaging with later stages of education. At this age problematic classroom behaviour particularly becomes apparent.

Disability, discrimination and criminalisation

The ways in which impairments may increase risks of antisocial behaviour or criminality are only part of the story. If we adopt a social model theory, we must also consider how social responses to neurodevelopmental impairment give rise to experiences of disability.

In particular, diagnosis (or lack of) and classification determine the extent and nature of recognition and response to impairment. This is key to a variety of experiences that can increase risk of offending.

For example, a failure to identify and respond to the learning needs of these young people may be the origin of disengagement from education and problem behaviour. Without an appropriate awareness of impairment, behaviour in the classroom may be attributed to the wrong underlying cause. A cognitive or affective impairment may be misinterpreted as a behavioural problem and the child may attract inaccurate and inappropriate labels.

Such experiences are also apparent in the criminal justice system. This potentially leads to discrimination and criminalisation.

A lack of recognition of neurodevelopmental impairment and its impacts on behaviour can result in a failure to identify and appropriately support the young people in question. This may be through insufficient knowledge or training, lack of appropriate assessment, or limited specialist services.

Generic youth justice interventions often assume typical levels of verbal and cognitive competence. Those assumptions may be inappropriate for some young people with impairments. This can increase the risk of failure to complete an order, leading to a breach and return to court for further sentencing.

People with impairments can have difficulties dealing with the justice system, which makes them more vulnerable to incarceration.shutterstock, CC BY-NC

An impairment can also hinder a young person’s ability to understand and engage in an alien and confusing legal process. Specific terminology and conceptual language can be particularly difficult to understand.

Research has highlighted how difficulties in narrative language skills (the ability to “tell their story”) present considerable barriers in the context of forensic interviewing techniques applied in court or by police. This can lead to poor expressive vocabulary or narrative skills and poor eye contact and body language. Such responses may be misinterpreted as behavioural and attitudinal, rather than due to communication difficulties.

Implications for reform of youth justice practices

Together this evidence suggests a widespread failure to recognise and meet the needs of vulnerable young people. It calls for a radical rethinking of our approaches and of interventions intended to prevent offending.

In particular, the research evidence suggests the need to:

• develop generic policing and youth justice procedures, practices and interventions that do not assume cognitive and communicative competence or understanding of procedures, and support better engagement and access to justice for all young people;

• assess for specific functional difficulties that might help understand the basis of offending behaviour by adopting screening tools that criminal justice professionals can use;

• consider the therapeutic potential of youth justice interventions to address underlying cognitive difficulties and emotional needs, drawing on expertise in health and other services; and

• ultimately shift resources away from expensive custodial interventions and instead invest in family support, educational and health services.

By more quickly and effectively identifying and meeting the developmental needs of vulnerable youth, we can help prevent offending and re-offending.

Nathan Hughes has received funding from the European Commission and the Office of the Children's Commissioner for England in support of this research.