The rapidly growing waiting lists for autism and ADHD assessments

With as many as 1.2 million autistic people in England, as well as up to 2.2 million people with attention deficit hyperactivity disorder (ADHD), providing the right support is no small ask. Jessica Morris assesses the data to reveal what is happening to referrals for autism assessments and prescriptions for ADHD medication in England, and looks at what might lie behind any recent changes.


Blog post

Published: 04/04/2024

Long waiting times for autism and attention deficit hyperactivity disorder (ADHD) assessments can prevent people from getting the vital care and medication they need. Health and education support often relies on a formal diagnosis, without which there can be severe negative consequences. A recent report warned that failure to provide children with effective autism support can lead to poor long-term outcomes, such as an increased prevalence of mental ill health and a greater risk of school exclusion.

Estimates show that there might be as many as 1.2 million autistic people and 2.2 million people with ADHD in England, and providing them with the right support is no small task. Recent news reports have highlighted a huge rise in demand for autism and ADHD diagnoses amid increased awareness and understanding of neurodiversity.

Exploring referrals and waits for autism and ADHD assessments is a key first step to understanding the scale of the issue, which can then be used to drive improvements and change. So what does the data tell us?

What is happening to referrals and waits for autism assessments?

The below chart paints a stark picture of the growing backlog of autism assessments for adults and children in England. In December 2023, there were 172,022 patients with an open referral for suspected autism – the highest number ever reported. Even when you restrict the data to account for the fact that the number of providers submitting data has increased over time, there has been a more than five-fold increase in the number of open suspected autism referrals since 2019 (see the data notes for more information).

Why has the waiting list for an autism assessment been increasing so rapidly? Each month there are hundreds more ‘new’ referrals for suspected autism than there are ‘closed’ referrals that have ended (patients being told whether or not they have autism). This is leading to a ballooning waiting list.

Patients are waiting longer for a first appointment after they have been referred. In December 2023, 79% of patients with a suspected autism referral who had been waiting over 13 weeks had not had a first appointment recorded. This compares with 44% of patients in December 2019. National Institute for Health and Care Excellence (NICE) guidance states that people with suspected autism should have a diagnostic assessment started within three months of their referral, so that appropriate health and social care interventions and support can be given.

Data on median waits for a first appointment demonstrate just how long patients with suspected autism are waiting beyond the recommended three months. Between October and December 2023, people who had a first appointment for suspected autism had a median wait of over nine months since their referral. This compares to the same period in 2019, when people waited over four months to be seen.

Some Integrated Care Boards (ICBs) have much longer waiting times. Between October and December 2023, one ICB reported the longest median wait for a first appointment of over two-and-a-half years. In some areas of the country the wait is closer to two months, and so there is a postcode lottery depending on where you live.

What about referrals and waits for ADHD assessments?

There is no national data published on referrals or waiting times for ADHD assessments, which means that the challenges can go unrecognised. A report in April 2023 presented a summary of NHS responses to Freedom of Information requests about ADHD waiting times, which showed large variation between areas with some people waiting months and others waiting years for a first appointment.

The Petitions Committee ran an online survey asking people their views on assessment waiting times for ADHD and autism, which was debated by MPs in February 2023. The survey found that, of the respondents who were waiting for an NHS ADHD assessment, 24% had been waiting between one and two years and 10% had been waiting between two and three years.

Meanwhile, the rise in demand for ADHD support can be seen through the lens of national prescribing data. Between 2019/20 and 2022/23, there was a 51% increase in the number of patients prescribed medication for ADHD.

This comes amid a backdrop of reports of national shortages of ADHD medications. Some people are not able to access their medications in the quantity or timescale they need.

The national prescribing data also shows that, while a larger volume of children and teenagers are prescribed medication for ADHD, there has been faster growth over time for adult prescriptions. Between 2019/20 and 2022/23, the 25-44 age groups saw the biggest increases in patients being prescribed ADHD medication. There was a 28% increase in the 10-14 age group, which compares to a 146% increase in the 30-34 age group.

What has been driving the surge in referrals and diagnoses for autism and ADHD?

The rise in referrals is partly due to increased public awareness of autism, ADHD and other neurodivergent conditions, which has led more people including adults to seek support. The Covid-19 pandemic accelerated this further, as people’s symptoms were unmasked amid lockdowns, school closures and working from home. The vocal work of charities and greater use of social media have also contributed to the increased awareness of neurodiversity.

Experts are currently undecided about whether the increase in diagnoses is due to more children having autism and ADHD, whether there has been a rise in overdiagnosis, or if there was previous unmet need and that people are now coming forward. Diagnoses have also been increasing because of wider assessment boundaries, that encompass more people for whom autism or ADHD would previously not have been considered. One study found that some NHS centres were twice as likely to diagnose adults as autistic, and that there is not a consistent ‘conversion rate’ between referrals and diagnoses across the country.

What next?

Demand for autism and ADHD assessments has risen at such speed that services are simply unable to keep up. The increase in awareness of neurodivergent conditions, together with workforce pressures, the pandemic and sustained underfunding, have led to growing backlogs and longer waiting times that are negatively affecting people’s day-to-day lives.

The impact on children should not be underestimated. Without a formal diagnosis, children and young people with suspected autism or ADHD may not be getting the support they need at school, which can significantly affect their life’s trajectory.

There are also hidden waits to access support for autism and ADHD, such as long waits for initial referrals, with some people requiring multiple appointments before further investigation is deemed necessary.

There is a need for better data, particularly in relation to ADHD assessments, for which there is currently no national data published. The quality of data for autism assessments could also be improved, such as by including autism diagnosis activity that happens in the Community Services Data Set.

The unprecedented surge in demand has happened at such a scale that it stands out as a serious problem even amid the wider challenges affecting health services. NHS England is establishing a taskforce on ADHD to improve understanding of this condition. A wider debate about the role of the NHS in the assessment, diagnosis and treatment of neurodivergent conditions is needed. In a health and care system where resources are so constrained, a broader response, working with other sectors including education, is likely to be required.

Data notes

NHS Digital’s Autism Waiting Time Statistics are classified as ‘experimental’ and should be treated with caution. Experimental statistics are new official statistics that are undergoing evaluation.

Autism diagnosis activity also happens in the Community Services Dataset (CSDS), but currently NHS Digital’s publication only includes data from the Mental Health Services Dataset (MHSDS).

Autism assessments for children and adolescents happen in two types of NHS services, child and adolescent mental health services and community paediatric services. Activity in community paediatric services is reported through the CSDS, so is not included. For this reason, we chose not to display the data for adults and children separately.

The number of providers submitting data to the MHSDS has increased over time. For our first chart showing open suspected autism referrals, the total for England includes data for all providers that are currently submitting at the time of this publication. The ‘providers that submitted data in Q1 2019/20’ restricts the timeseries to only include providers that submitted any data on open suspected autism referrals in April, May or June of 2019.

The statistic on there being a more than five-fold increase in open suspected autism referrals since 2019, restricted to only include providers submitting data in Q1 2019/20, was calculated by averaging the number for October to December 2023 (107,195) and comparing this to the number in April to June 2019 (19,028).

There have been some changes in methodology over time, including how a referral for suspected autism is counted as open. Other data quality issues include the completeness of the data providers submit. More information can be found on the NHS Digital website.

The BNF Section Name ‘CNS stimulants and drugs used for ADHD’ was used to specify the total identified patients being prescribed medication for ADHD. Detail on the quality of the NHS Business Services Authority’s prescriptions data can be viewed here.

Suggested citation

Morris J (2024) “The rapidly growing waiting lists for autism and ADHD assessments" QualityWatch: Nuffield Trust and Health Foundation.