A major new analysis has fueled concerns over the accuracy of tests that diagnose ADHD, suggesting many of those told they have the disorder are in fact suffering depression. 

Scientists from Scandinavia and Brazil analysed common methods of diagnosing adult ADHD described in nearly 300 medical studies. 

Many of these diagnostic tests are currently used by doctors in the UK to spot the condition. 

The findings showed that in nearly half the studies, the scientists failed to rule out other causes of ADHD-like symptoms, such as depression.

This means, they concluded, that the diagnostic test used may be unreliable, and therefore providing inaccurate results in the real world. 

‘You don’t actually know if subjects have other mental disorders such as depression or schizophrenia,’ the experts wrote in their report.

The latest findings come amid a rapid rise in adult ADHD diagnoses in the UK, with cases rising 20-fold over the last two decades.

It’s a phenomenon that has raised the concern of some of the country’s top psychologists and spurred a NHS investigation, launched in March.

Fascinating graphs show how ADHD prescriptions have risen over time, with the patient demographic shifting from children to adults with women in particular now driving the increase

Experts have warned that rogue private clinics are over-diagnosing the condition and have questioned the widespread prescribing of powerful stimulant drugs to treat it.

In the latest analysis, scientists found that a psychiatrist or psychologist made the diagnosis in only 35 per cent of ADHD cases examined. 

Adults in the UK can only be formally assessed for ADHD on the NHS by a psychiatrist, psychologist or specialist ADHD nurse. 

In some cases discovered by the researchers, it was explicitly stated that the assessment and diagnosis of ADHD was made by subjects themselves. 

One patient was reported to have reached their diagnosis with the help of a computer, the researchers explained.

‘In psychiatry, we really need that all diagnoses, not just ADHD, are made with the same uniform criteria and by trained professionals,’ said co-author of the study, consultant psychiatrist Dr Julie Nordgaard from the University of Copenhagen.

‘Otherwise, we cannot rely on the results or compare them across studies.

‘Especially in a situation where a diagnosis such as ADHD in adults is increasing, we need to be very thorough and have a solid foundation.

Sheridan Smith, 42, has revealed she has been diagnosed with Attention Deficit Hyperactivity Disorder (pictured in 2023)

Former Bake Off host Sue Perkins (left) last year shared that she had been diagnosed and that ‘suddenly everything made sense – to me and those who love me’. Love Island’s Olivia Atwood (right) said ADHD made her ‘constantly overwhelmed’

‘Otherwise, we risk too many people getting a wrong diagnosis and not being able to give them the most effective treatment. 

‘Or they risk receiving unnecessary treatment that causes side-effects.’

Symptoms of depression can often mimic those of ADHD, research has shown. 

A neurodevelopmental disorder, ADHD affects concentration, impulse control and activity levels.

Common symptoms include restlessness, distractibility, forgetfulness, difficulty following instructions or managing time, and making impulsive decisions.

Depression, which affects roughly one in six adults in the UK, can look remarkably similar. 

Those with the mood disorder often experience poor concentration, low energy and disturbed sleep. 

Both ADHD and depression can also cause changes in appetite, restlessness and irritability as well as difficulty initiating and completing tasks. 

How ADHD rates compare between countries, according to US official sources

Schizophrenia, though less common—affecting just one per cent of the UK population —can also resemble ADHD in some cases.   

Traditionally characterised by psychotic symptoms like hallucinations and delusions, schizophrenia can also cause attention problems, particularly in its early stages. 

The researchers concluded it’s impossible to know which disorders and symptoms were actually being affected by the treatments investigated in the trials. 

‘This makes the research results from many of these clinical trials difficult to utilise,’ said associate professor at the University of Copenhagen Dr Mads Gram Henrikson.

The study comes just months after the latest NHS figures revealed more than 549,000 people in England were waiting for an ADHD assessment at the end of March 2025—up from 416,000 the previous year.

Of those currently waiting for an assessment, around 304,000 had been waiting at least a year—and 144,000 for two years or more, as NHS services struggle to keep up with spiraling demand.

More than two-thirds (382,000) were aged between five and 24.

Last year a MailOnline investigation revealed that doctors were dishing out powerful ADHD drugs at 10-times the rate in some parts of England than others.

NHS data shows as many as one in 100 people in some areas are taking ADHD medications, compared to just one in 1,000 in nearby regions.

Commenting on the findings, experts warned of over-diagnosis and ‘mass-prescribing’ could be putting public health at risk.

University College London psychiatrist Professor Joanna Moncrieff, a vocal critic of medication overuse, said ADHD diagnosis is ‘incredibly subjective’.

‘One psychiatrist may think almost everyone has it, while another thinks very few do,’ she said. ‘We all have ADHD symptoms to some extent.’

She added that private clinics are often quicker to diagnose than the NHS, making a diagnosis more likely in the independent sector.

Professor Moncrieff said patients were increasingly demanding an ADHD diagnosis as the ‘answer’ to problems they are experiencing in areas like their work.

‘This concept of ADHD has got out there and everyone is reinterpreting their difficulties in the light this new idea, ‘I’m not bored and don’t like my job, I have ADHD’,’ she said.

‘Stimulants make people feel good, they make them feel confident, they make people feel a little bit euphoric, energetic, so of course people are going to be rating themselves as doing better.’

Rising interest in ADHD is thought to be fueled in part by celebrities sharing their diagnoses — including Katie Price, Love Island’s Olivia Attwood, Sheridan Smith and former Bake Off host Sue Perkins.

Attwood said it caused ‘a lot of stress’ in her teens, while Price said it explained why she never felt there would be ‘consequences’ for her actions. Perkins said the diagnosis made ‘everything make sense’.

Social media has also been blamed, with users praising ADHD meds for calming them and boosting focus.

NHS prescriptions have doubled in six years to 230,000, with the sharpest rise—nearly 60 per cent in a year—among women in their late 20s and early 30s.

Use among 25 to 39-year-olds has increased five-fold since 2015.

In response, NHS England launched a taskforce to assess the scale of the condition.

ADHD is also behind a surge in disability benefit claims. One in five now relate to behavioural conditions, with over 52,000 adults—mostly aged 16 to 29—listing ADHD as their main condition.