The NHS is overwhelmed with patients waiting to be assessed for ADHD and autism, with demand soaring five times since before the pandemic.

The Nuffield Trust found that there are as many as 1.2 million people in the UK with autism and 2.2 million people with attention deficit hyperactivity disorder (ADHD).

The think tank reported that some 172,000 people were waiting for expert assessment to receive a formal diagnosis of autism in December, a fivefold increase from the 32,320 people waiting four years ago.

More than half of those on the waiting list are children and young people, which poses a significant risk to their educational progress as they may not receive the extra help and support they need.

In addition to massive waiting lists, there are reports of nationwide shortages of ADHD medications. More than a quarter of patients claim they are unable to access treatment after drug shortage alert issued in 2023, Pharmaceutical Journal established.

Although the National Institute for Health and Care Excellence (Nice) recommends that people with suspected autism should be diagnosed within three months of referral, some 147,070 patients waited at least 13 weeks in December. That’s more than six times the 24,250 people who had to wait in December 2019.

The number of people aged 30 to 34 taking medication to treat ADHD increased by 146%.

New analysis of data from the Nuffield Trust found that 79% of people waiting 13 weeks or more did not get their first appointment with a specialist, up from 44% in December 2019.

Services have simply been unable to keep up with the surge in demand for testing, which experts believe is due to rising public awareness of the situation leading to more people seeking support.

The Covid-19 pandemic has exposed symptoms to many people as they have been forced out of their normal lives during lockdowns, schools and workplace closures.

Experts have yet to reach consensus on whether the increase in diagnoses is due to an increase in children with autism and ADHD, or whether previously unmet needs are causing people to now seek support.

Thea Stein, chief executive of the Nuffield Trust, said: “The extraordinary, unpredictable and unprecedented growth in demand for autism assessment and ADHD treatment has completely exceeded the capacity of the NHS to meet it.

“Frankly, it’s impossible to imagine how systems can grow quickly enough to meet this demand.

“We should not underestimate what this means for children: many schools want support through assessment and formal diagnosis, and children and their families suffer while they wait.”