Does the UK have a mental health overdiagnosis problem?

The Guardian

05-04-2025

When the health secretary, Wes Streeting, suggested the 'overdiagnosis' of some mental health conditions was a factor in the government's welfare changes, many saw the comments as playing into an unhelpful culture-war stereotype of coddled millennials – and as echoing Rishi Sunak's claim, a year ago, that there was a 'sicknote culture' plaguing Britain's economy.
But media coverage of Dr Suzanne O'Sullivan's recent book, The Age of Diagnosis, has amplified and lent credibility to the idea that a diagnosis, in itself, can risk limiting an individual's life prospects.
Streeting's comments came amid plans for substantial cuts to personal independence payments (Pip), after the government concluded that the overall bill for disability benefits, which rose by nearly £13bn to £48bn between 2019-20 and 2023-24, was on an unsustainable trajectory. Much of the increase in spending is linked to a huge rise in the number of working-age adults claiming disability benefits linked to mental ill health on a scale that demands a policy response. At the heart of the debate is the question of what has caused this increase and how it could be reversed.
In 2002, mental and behavioural problems were the main condition for 25% of claimants. By 2024, the figure had risen to 44%, with more than half (55%) of the post-pandemic rise in disability benefits accounted for by claims primarily for mental health, according to a report by the Institute for Fiscal Studies (IFS) thinktank. The same report found 'compelling evidence that mental health has worsened since the pandemic' and experts agree with this assessment.
'We observe clear trends of increasing mental ill health,' says Dr Darío Moreno-Agostino, who researches population mental health at University College London and King's College London. His team's analysis of longitudinal data, tracking cohorts born in 1970, 1958 and 1946, suggests that fafter the pandemic all three generations reached or surpassed the worst mental health levels in 40 years.
'We don't know exactly the reasons, but there are some clear candidates,' says Moreno-Agostino. 'Socioeconomic adversity is one of the fundamental measures of mental health inequalities. I don't think that there's evidence that this is due to overdiagnosis.'
NHS records reveal similarly stark trends. The number of people in contact with secondary mental health services rose by 600,000 between 2019 and 2024 – a 45% increase in five years, according to data from the Care Quality Commission, which said the increase in appointments had not kept pace with this trend. In June 2024, very urgent referrals to crisis teams for adults were 45% higher than just one year earlier. Rates of common mental disorders more than doubled in 16- to 24-year-olds between 2000 and 2019 and have increased more steeply since then.
As the NHS has struggled to keep pace, clinicians are witnessing a steady increase in the severity of cases, designated green, amber or red. 'In the past we'd see a mixture of green, amber and red,' says Prof Daisy Fancourt, the head of the social biobehavioural research group at UCL. 'Now it's basically all red cases and a few amber. There isn't actually the space to see the greens.'
Fancourt, too, is sceptical that overdiagnosis is at play. 'We're going through extremely difficult times for young people,' she says. 'Poverty, Covid disrupted young people's lives at a critical time, the difficulty securing housing and employment, existential challenges, global strife, climate change. On top of that we have challenges around social media and increased availability of global news.'
There are also striking inequalities in who receives a diagnosis, according to a recent study by Prof Susan McPherson, a social psychologist at the University of Essex. The research found there were 12 times as many people with 'undiagnosed distress' (symptoms severe enough to meet clinical diagnostic criteria) as there were people with diagnoses in the absence of clinically significant symptoms, using data from the UK Longitudinal Household Study. The 'overdiagnosed' group was so small, McPherson says, that they were almost excluded from the analysis for statistical reasons.
People living with a disability had nearly three times the risk of undiagnosed distress compared with those without a disability and women had 1.5 times the risk of being undiagnosed. Both these groups were also at greater risk of having questionable diagnoses (although in much smaller numbers) highlighting that over- and under-diagnosis coexist in a health system that, the study suggests, is designed around 'patriarchal and ableist concepts of normality'. 'They can be misunderstood in both ways,' says McPherson. 'It suggests that mental health services just aren't geared up to meet their needs.'
While her research undermines Streeting's claim, McPherson is critical of an 'over medicalisation' of mental health.
'There's a huge problem out there and we can't make it go away just by saying it's overdiagnosis. But diagnosing it all is not the solution either,' she says. 'The answer is looking at the problem from a more social and economic perspective.'
Speaking to experts, a recurring theme is the role of social and economic adversity in mental ill health and the NHS is grappling with how to reflect this at a time of widening inequalities. Social prescribing, which aims to improve the health and wellbeing of patients by connecting them to community resources and activities, has tripled in the last three years.
'A lot of the time when people have milder problems there can be community-based solutions,' says Fancourt, who is running trials of social prescribing for young people on mental health waiting lists and in schools. Participants are offered six hour-long sessions with a link worker, who supports them in taking up hobbies, getting involved in volunteering, sport, social activities or dealing with practical challenges around transport or housing. The concept has faced some criticism, with one study of 6,500 people failing to identify evidence of efficacy and concerns over whether patients might feel dismissed. Fancourt agrees that further research is needed, but said demand for the schemes had been far greater than anticipated.
'It's extremely popular across age groups,' she says. 'It's not a pill, it's not a stigmatising treatment. People are building new identities that are based around their hobbies. It's an asset rather than a deficit-based approach.'
There is also a question of how the welfare system has played a role in shaping the public conversation around mental health.
'The way the system has been designed, you're either fit for work or ill,' says Dr Annie Irvine, a lecturer in social policy at the University of York.
'The only part of people's life situation that the welfare system is interested in hearing about and legitimising is the health part,' she adds. 'No matter what other issues you're also dealing with – housing, lone parenthood, domestic violence, relationship breakdown, caring – the only part of that the system has a space for at the moment is the mental distress part.'
Irvine is not questioning the legitimacy of people's mental distress. 'This idea of shirkers and scroungers claiming benefits by choice is just not reflected in the research I have done,' she says. However, based on her qualitative research with welfare recipients, she argues that mental health is often not the only significant barrier to employment.
'The barriers to work are much broader than that,' she says. 'To bring those numbers down, you need to look beyond the medicalised explanation for worklessness.'
The government's green paper, Irvine says, shows some encouraging signs of recognising this bigger picture.
Many are concerned, though, that 'overdiagnosis' is a politically convenient idea at a time when squeezing benefits spending is a priority and when the more ingrained determinants of mental health are difficult to fix.
'Identifying it as an individual crisis of care speaks to a wider political motive,' says Prof Ewen Speed, a medical sociologist at the University of Essex. 'It backgrounds a social crisis of inequality. To talk about this as overdiagnosis is a mischaracterisation of the scope of the problem.'