Attention-deficit hyperactivity disorder (ADHD) could be more predictive of poor mental health outcomes in adults than autism spectrum disorder (ASD), according to a UK study.
A research team led by the University of Bath found that anxiety and depression were more common among adults with high levels of ADHD than those with high levels of ASD, and said they hoped their findings would prompt further investigations.
They said that most of the research efforts and clinical practice had concentrated on associations between ASD and mental health problems, including anxiety, depression, and obsessive-compulsive disorder. However, whilst internalising disorders associated with ASD were also present in people with ADHD, fewer studies had investigated the link between ADHD and mental health, particularly among adults.
Co-occurrence of ASD and ADHD, estimated to affect around 28% of individuals with autism, meant that researchers had "struggled to statistically separate the importance of ADHD and autism for mental health outcomes because of how frequently they occur together", said Luca Hargitai, a PhD researcher at the University of Bath's Department of Psychology, who led the investigation.
The study, published in the journal Scientific Reports, involved 504 UK adults who self-reported using the short autism-spectrum quotient and the adult ADHD self-report scale questionnaires, as well as completing questionnaires for generalised anxiety and depression.
Call for a 'Shift' of Focus from Autism to ADHD
The results suggested that both ASD and ADHD traits predicted greater internalising problems than those without either condition. Further analysis also indicated that ADHD traits might be a stronger predictor of internalising problems than ASD traits. "Overall, we report converging evidence that ADHD traits are a stronger and more important predictor of internalising problems than ASD traits," the researchers wrote.
The authors noted limitations of the study, including the brevity of self-reported questionnaires used, the overlap of traits in cases of ASD and ADHD, and the lack of ethnicity data.
Nevertheless, 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."
Dr Punit Shah, PhD, associate professor of Psychology at the University of Bath, and the study's senior author, commented: "Further research is now needed to delve deeper into understanding exactly why ADHD is linked to poor mental health, particularly in terms of the mental processes that might drive people with ADHD traits to engage in anxious and depressive thinking.
"At the moment, funding for ADHD research – particularly psychological research – is lacking. This is especially pronounced when you compare it to the relatively high level of 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 better understand ADHD in adulthood."
Dr Tony Floyd, CEO of the ADHD Foundation neurodiversity charity, 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 research being commissioned 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 both primary and secondary care, are now more apparent."
In a press release, the University of Bath noted that the study was published on so-called 'Blue Monday', which has achieved popular status as the gloomiest day of the year. Attributed to a combination of Christmas debt, poor weather increasing the risk of seasonal affective disorder, and low levels of motivation, Blue Monday, which falls on the third Monday in January each year, dates back almost 20 years to a marketing campaign by a holiday travel firm.
In a statement today, Dr Subodh Dave, dean of the Royal College of Psychiatrists, said: "While this formula may not be real, we do know that more people are struggling with their mental health than ever before."
He added: "We are now in the middle of January and many people are starting to feel the full effects of the cost-of-living crisis.
"Families are being forced to choose between heating their homes and feeding themselves. That is a decision that nobody should be forced to make, and would undeniably make anyone stressed or anxious, but in more severe cases it can also contribute to serious mental health problems."
This work was supported by a GW4 award, Neurodevelopmental Neurodiversity Network. The authors declared no conflicts of interest.