Children in England and Wales aged 15 or 16 are now more likely to be receiving disability benefits than adults in their 20s to 40s, according to research highlighting a sharp increase in claims resulting from conditions such as autism and ADHD.

In a new report, the Resolution Foundation thinktank points out that the number of children whose families receive disability living allowance (DLA) has more than doubled in the last decade, to 682,000.

The biggest shift has come among teenagers, with 8% of all 15-year-olds receiving DLA last year, up from 5% in 2013.

As a result, the research finds that it is only among adults aged 52 and above that the proportion claiming disability benefits is now higher than for 15- and 16-year-olds.

The thinktank says the increase in DLA payments has been “almost entirely driven by awards made to children whose main condition is either a learning difficulty, behavioural disorder or attention deficit hyperactivity disorder (ADHD)”.

Understanding and diagnoses of such conditions have increased rapidly in recent decades. A study by UCL researchers found a 20-fold increase in diagnoses of ADHD between 2000 and 2018. Another paper found that autism diagnoses had shot up by 787% over the 20 years from 1998.

Louise Murphy, the author of the report and a senior economist at the Resolution Foundation, said: “The rising prevalence of disability across Britain is driving up the number of children awarded disability benefits, and that increase is most stark among older children.”

The report suggests part of the shift may reflect the rapid increase in parents applying for extra support with their children’s special educational needs in the classroom.

“It is plausible that some of this pressure is showing up in child disability benefit claims, with families being more likely to apply for child DLA after receiving a diagnosis or description of their child’s additional needs,” it said.

However, Murphy warned of a sharp drop-off once claimants reached adulthood, with 25% of those in receipt of DLA not going on to receive the personal independence payment (Pip), which adults with disabilities can apply for.

“There may be positive reasons for no longer claiming support, but it is a huge worry if young people are leaving the benefits system and missing out on support at the arbitrary cut-off point of age 16, rather than when their condition changes,” Murphy said.

James Taylor, executive director of strategy at the disability equality charity Scope, said: “It’s worrying that such a big number of young disabled people are losing out on financial support as they reach adulthood.

“Life costs a lot more when you’re disabled, and benefits like DLA and Pip are an absolute lifeline to help cover those extra costs.”

“Our benefits system is incredibly complex, adversarial and difficult to navigate, so we know the transition from DLA to Pip can be challenging and stressful. The new government needs to look into the real reasons behind these figures, and work with disabled people to fix our broken welfare system,” he added.

Dan Paskins, director of policy, advocacy and campaigns at Save the Children UK, said: “These figures are cause for concern for the UK government as we also know children living with a disability are more likely to be growing up in families experiencing poverty.

“Our social security system must support disabled children in their earliest years but also during the critical time of entering adulthood. It’s clear from this research that politicians need to analyse the support system for children with disabilities as they grow older.”

DLA, which includes a “mobility” and a “care” component, is worth between £28.70 and £184.30 a week, depending on how much additional help the child is deemed to need.

With claims rising sharply, the total cost of paying the benefit has increased from £1.9bn to £4bn in real terms over the past 10 years.

The spending watchdog the Office for Budget Responsibility has forecast that the cost of all disability benefits will increase by almost half over the next five years, to £58bn. As well as DLA and Pip, this includes attendance allowance, paid to older adults with care needs.

A government spokesperson said: “We are committed to ensuring parents of children with disabilities are supported fairly, including those with neurodevelopmental conditions as awareness and formal diagnoses have increased.

“As children enter adulthood, support will continue for those who need it and we are committed to breaking down the barriers so there is opportunity for everyone.”