Adults with high levels of attention-deficit hyperactivity disorder (ADHD) symptoms are more likely to experience anxiety and depression than adults with high levels of autistic traits, according to new research led by psychologists at the University of Bath in the UK.

This study is the first to show that ADHD predicts poor mental health outcomes in adults more than other neurodevelopmental conditions, like autism.

Until now, there has been a dearth of information on the effects of ADHD on poor mental health, with far more research focusing on the impact of autism on depression, anxiety and quality of life. As a result, people with ADHD often struggle to access the clinical care they need to cope with their symptoms.

The study’s authors hope their findings will trigger new research into ADHD and ultimately improve the mental health outcomes for people with the condition. ADHD is a neurodevelopmental condition characterised by inattention and/or hyperactivity and impulsivity. The condition is estimated to affect between 3% and 9% of the population.

Blue Monday

Speaking on Blue Monday (January 16) – the third Monday of January, described by some as the gloomiest day of the year – lead researcher, Luca Hargitai, said: “Scientists have long known that autism is linked to anxiety and depression, but ADHD has been somewhat neglected.

“Researchers have also struggled to statistically separate the importance of ADHD and autism for mental health outcomes because of how frequently they occur together.”

Ms Hargitai, a PhD Researcher at Bath, added: “Our aim was to precisely measure how strongly ADHD personality traits were linked to poor mental health while statistically accounting for autistic traits.”

The new research – a collaborative effort between the Universities of Bath, Bristol and Cardiff, and King’s College London – is published this week in the prestigious journal Scientific Reports. It comes in the same month that two British TV personalities – Johnny Vegas and Sue Perkins – have opened up about their recent diagnoses of ADHD.

“The condition affects many people – both children and adults – and the fact that more people are willing to talk about it is to be welcomed,” said Ms Hargitai. “The hope is that with greater awareness will come more research in this area and better resources to support individuals in better managing their mental health.”

Overly active, as though driven by a motor

The study used a large, nationally representative sample of adults from the UK population. All participants completed gold standard questionnaires – one on autistic traits, the other on ADHD traits – responding to statements such as “I frequently get strongly absorbed in one thing” and “How often do you feel overly active and compelled to do things like a motor drove you?”

The researchers found that ADHD traits were highly predictive of the severity of anxiety and depression symptoms: the higher the levels of ADHD traits, the more likely a person is to experience severe mental health symptoms. Through innovative analytical techniques, the study authors further confirmed that having more of an ADHD personality was more strongly linked to anxiety and depression than autistic traits.

These results were replicated in computerised simulations with a 100% ‘reproducibility rate’. This showed, with great confidence, that ADHD traits are almost certainly linked to more severe anxiety and depression symptoms in adults than autistic traits.

Shifting the focus of research and clinical practice

Ms Hargitai said: “Our findings suggest that research and clinical practice must shift some of the focus from autism to ADHD. This may help to identify those most at risk of anxiety and depression so that preventative measures – such as supporting children and adults with the management of their ADHD symptoms – can be put in place earlier to have a greater impact on improving people’s wellbeing.”

According to Dr Punit Shah, senior author and associate professor of Psychology at Bath, another important aspect of the new study is that it advances scientific understanding of neurodevelopmental conditions.

“By addressing the shortcomings of previous research, our work provides fresh information about the complex links between neurodiversity and mental health in adults – an often overlooked area.

“Further research is now needed to delve deeper into understanding exactly why ADHD is linked to poor mental health, particularly in the mental processes that might drive people with ADHD traits to engage in anxious and depressive thinking.

“Currently, funding for ADHD research – particularly psychological research – is lacking. This is significantly pronounced compared to the relatively high funds directed at autism.

“As the evidence becomes clear that ADHD isn’t just a childhood condition but persists throughout life, we must adjust our research agendas to understand ADHD in adulthood better.”

Commenting on the new findings, Dr Tony Floyd, CEO of ADHD Foundation, The Neurodiversity Foundation, said: “This research demonstrates clear evidence of the increased risks of mental health comorbidities associated with adult ADHD. This is a step towards recognising the broader impact of unmanaged and untreated ADHD. We hope this research will lead to more commissioned research in this area. We also hope it will result in changes to the design and delivery of health services.

“The cost implications to the NHS of leaving ADHD untreated, and the need to better train health practitioners in primary and secondary care, are now more apparent. And of course, there are other costs too that need to be considered – to the health of UK citizens with ADHD and to their family life, employability and economic well-being. These costs are often hidden, but they are considerable.

“This research from Bath University will add to the growing national debate and the business case for a national review of health services for ADHD across a person’s lifespan.”