A Failing System of Care?

In the early 1990s, while working at the Maudsley Hospital in London, clinical and forensic psychologist Susan Young began to notice a troubling trend. Young people diagnosed with conditions such as attention deficit hyperactivity disorder (ADHD) were missing appointments, only to resurface months later. Many sheepishly admitted that they had been in prison. 

“Of course it was not a huge surprise, because around 50% of children with ADHD will also have conduct problems. That’s been known for many years,” Young told Medscape News UK. “Not all of them will go on to have careers in crime and many will get off that path,” but many will continue, she added.

Young, who now runs a private practice, has been researching the link between ADHD and criminal behaviour ever since. She was the lead author of one of the first meta-analyses examining ADHD prevalence among incarcerated populations.

Is it One in Four?

Published in Psychological Medicine a decade ago, Young’s meta-analysis found that approximately 25% of prisoners met diagnostic criteria for ADHD. A subsequent meta-analysis, published in Frontiers Psychiatry, calculated the prevalence at around 26%.

The figures suggested ADHD rates among prisoners were 5-10 times higher than in the general population. The National Institute for Health and Care Excellence (NICE) currently estimates ADHD affects 3%-4% of adults and 5% of children and young people.

However, more recent data have challenged the estimate of 1 in 4. A 2024 meta-analysis by Professor Seena Fazel of the University of Oxford and Dr Louis Favril from Ghent University, Belgium, published in Criminal Behaviour and Mental Health, put the figure closer to 8% or possibly lower.

Fazel has attributed the earlier estimates to methodological issues in previous studies, including reliance on self-reported symptoms and selected sampling. “If a screen was followed by a more detailed assessment (2-phase design), prevalence was systematically higher,” he wrote. “We think it may be related to a form of confirmation bias or (medication and other perceived) consequences from this diagnosis in prison.”

The Numbers Behind the Debate

Regardless of whether the rate is 25% or 8%, the figures are sobering. According to Ministry of Justice (MoJ) and HM Prison & Probation Service (HMPPS) data, more than 325,000 individuals were in the criminal justice system in England and Wales as of December 31, 2024. This includes 85,372 prisoners and 240,497 people on probation.

A 25% prevalence rate would suggest over 81,000 people with ADHD are involved in the system; even an 8% rate equates to at least 26,000 individuals.

“Certainly lots of young offenders appear to have ADHD,” said Professor Philip Asherson, emeritus professor at King’s College London and a director of the UK Adult ADHD Network that provides support, education, and training for professionals who work with adults with ADHD.

“There’s a question about how to identify ADHD early and give people the right kind of support for their ADHD and their behaviour, to try and direct them away from the criminal justice service,” the recently retired psychiatrist told Medscape News UK.

ADHD and the Path to Offending

NICE defines ADHD as a neurodevelopmental condition characterised by persistent inattention hyperactivity or impulsivity that interferes with functioning or development.

Asherson, who was a member of NICE’s ADHD guideline development group, said the condition “generates emotional instability, impulsive behaviour, and is associated with difficulty attending [school]. So it’s hard for people to learn, to do well in education.”

He noted that many individuals with ADHD struggle academically, a pattern also seen widely in prison populations. MoJ data from 2022-2023 indicate that 28% of prisoners had a confirmed learning difficulty or disability. 

Limited education and few life opportunities, coupled with undiagnosed ADHD, may lead some young people to land on the wrong side of the law, Asherson observed.

“In the prison I worked in, a lot of them were drug dealers or linked in some way to drug-related activity,” he said. “I guess that was a way of functioning or making money if you were unable to hold down a job and were poorly educated.”

ADHD and Reoffending Risk

Research has also shown that 96% of prisoners with ADHD have at least one comorbidity, Young said. “If you compare prisoners with ADHD to prisoners without ADHD, and you look at the comorbidity, they have higher rates of everything. They have more severe anxiety, more severe depression.” Young, who is also an honorary professor at Reykjavik University in Iceland, also noted: “They’re revolving door criminals, because they’re going in and out, in and out [of prison].” 

Young and other researchers have reported that prisoners with ADHD are more likely to reoffend, enter the criminal justice system earlier, make false confessions, and engage in risky behaviours such as substance misuse.

Misunderstood and Misdiagnosed 

Young, alongside Kelly Cocallis from Northumbria Healthcare NHS Foundation Trust, highlighted that offenders with ADHD are “ disadvantaged within the system.” They are disadvantaged because ADHD symptoms are often under recognised and/or misunderstood and their diagnosis of ADHD “may be missed or misdiagnosed.”

This was the experience of Jan (not her real name), an ex-offender supported by Working Chance, a charity which helps women with criminal records find employment. 

Jan was initially diagnosed with emotionally unstable personality disorder. “When I looked into it more, I didn’t think the diagnosis was right,” she told Medscape News UK. She eventually sought a private ADHD assessment in 2018. By then, her life was already in crisis, embroiled in court proceedings that resulted in her children being taken into care.

Jan had to wait until 2021 for the NHS to confirm the ADHD diagnosis. It was too late to avoid a cascade of events: poor educational performance, teenage pregnancy, a string of abusive relationships, and, finally, a criminal conviction.

“I was quite vulnerable at the time of my offence,” Jan said. “Because I hadn’t really felt affection and was in a vulnerable place, it all added up. I feel like if I’d been able to manage my emotions, which is hard with ADHD, I potentially wouldn’t have ended up in that situation. The decision-making would have been slightly different.”

Jan said her ADHD was largely ignored in the first prison she was sent to. “I don’t think they really took that into consideration. As soon as you walk into the prison, it’s like you’re cut off from society and everything stops.”

“There needs to be more help in closed prisons,” she said. “If you’ve only got one neurodiversity lead and they’re not doing their job, you’re letting down 150 people.”

Conditions were better in the second prison, where staff were more responsive. “The neurodiversity lead in the open prison was very invested in me,” Jan said. “She said she felt like I was in the criminal justice system for the wrong reasons, like the system had failed me.”

Gaps in Post-Release Support

Jan’s challenges continued after her release. “I’ve found it very difficult to handle changes,” she said. Frequent housing moves disrupted referrals. “There just seems to be some sort of drop in the system when you’re released.”

Confusion over probation conditions also caused distress. On several occasions she has said to her probation officer, “please, just send me back to jail.”

Young pointed out that many former inmates struggle to access care, lacking even a registered GP to renew prescriptions.

According to the MoJ, entrants to the prison system should receive an initial health screen within 24 hours. This is followed by a full health assessment within 7 days. This provides “opportunities for identification of known conditions or needs, as well as capturing any required reasonable adjustments,” Medscape News UK was told. 

Although HMPPS takes a needs-led approach to supporting people in prison, they “would not attribute any additional needs that are identified during the screening process to a specific clinical condition ourselves but do encourage individuals to self-declare any conditions or needs they consider themselves to have.” 

HMPPS introduced the neurodiversity support manager (NSM) role in 2021 to improve support for people with ADHD and other neurodivergent conditions while they were behind bars. NSMs were responsible for providing training and guidance to prison staff to help them not only identify prisoners who may need extra support but also to ensure that neurodivergent prisoners had access to appropriate education, skills, and work opportunities within the prison.

Communication and understanding was a big issue for Jan: “Some of my licence conditions they’ve put there haven’t really been explained. So, I’ve then done things that have potentially breached my licence without knowing it.”

Does Medication Help?

The evidence on whether medication reduces reoffending is mixed. Asherson and colleagues conducted a large randomised double-blind trial in the UK to assess the effects of methylphenidate on ADHD in a prison population. However, the results were null, which was somewhat unexpected.

“It was a bit surprising at the time because prior research had suggested there was a very large effect of medication,” Asherson said.

Asherson referred to a large Swedish trial that found lower reoffending among offenders treated for ADHD. There were also data to show that they were less likely to show violent behaviour. 

Data are conflicting as to whether treating people diagnosed with medication while in prison actually has an influence on their overall outcomes. 

Calls for Change

Young told Medscape News UK: “There’s so much research. There’s so many arguments” that ADHD is prevalent in the prison population and that it urgently needs addressing. 

Like Asherson, Young also sat on the NICE ADHD guideline working group and noted that research was not being translated into practice. 

One issue is the lack of data. When Medscape News UK contacted the MoJ under a freedom of information request to ask how many people within the prison system had a diagnosis of ADHD, the response received was that clinical diagnoses of neurodevelopmental conditions such as ADHD fell under the remit of NHS England.

NHS England published its first national-level data on ADHD prevalence and assessment  as recently as May 2025. The document acknowledged the need to improve data quality.

Henry Shelford, the chief executive of ADHD UK, criticised the delay, noting that NICE first published guidelines for ADHD in the year 2000. “For NHS England to take 25 years to create any population estimate is an expression of their abject failure to properly manage and resource ADHD,” he told The Guardian.

Takeda, a pharmaceutical company which manufactures several drugs for treating ADHD, has been campaigning for better ADHD recognition in the criminal justice systemfor several years. 

In 2024, it filed freedom of information requests with 44 prisons. Only seven (16%) replied, and none could provide data on ADHD diagnoses, screening practices, staff training, or prisoner support.

Young called the results “really frustrating.” “I’ve been at this since the mid 90s, and it just seems to be cyclical. I just think, when is something going to be done?” 

Is Reform Finally on the Way?

There are some signs that change may be coming. In March 2024, NHS England launched a national task force to examine system-wide ADHD challenges, including access, diagnosis, and care pathways. While not specifically focused on the criminal justice system, its first interim report in June 2025, highlighted the need for “cross-agency and cross-government department working focused on the whole person” and early recognition of neurodivergent conditions.

Young welcomed the effort but warned that clinicians and professionals should consider the wider consequences of having the condition. 

“They may be seeing people with ADHD, but they just don’t know it,” Young said. “We don’t routinely ask, ‘have you committed a crime?’ ‘Have you ever been convicted of something?’ But perhaps we should.”

Young acknowledged she had received speakers’ fees from Takeda, and previously from Eli Lilly & Company, Flynn Pharma, Janssen, Novartis, and Shire. She had also received research grants from Eli Lilly & Company, Janssen, and Shire. Asherson has consulted for Eli-Lilly & Company, Flynn Pharma Jannsen-Cilag, and Shire. 

Sara Freeman, BSc, MSc, is a freelance medical journalist based in London, UK. She has been reporting for specialist healthcare news organisations for more than 20 years.