Adult diagnoses of attention deficit hyperactivity disorder (ADHD) rose almost 20-fold among men in the UK between 2000 and 2018, possibly due to an increased awareness of the condition.
Doug Mckechnie at University College London and his colleagues analysed anonymised records from National Health Service doctors collected throughout the UK over those 18 years.
“A lot of it is the increasing awareness amongst patients and clinicians, making it more likely that their symptoms are detected and attributed to ADHD,” says Mckechnie. Common symptoms include difficulty concentrating, hyperactivity and impulsiveness.
The increase in cases could also be due to a better understanding of how ADHD continues beyond childhood, he says. “It used to be thought that most people stopped having ADHD once they reached adulthood, but this is no longer thought to be the case,” says Mckechnie.
Among children, diagnoses also rose over that 18-year period in all age groups aside from those between 3 and 5 years old, where rates approximately halved in boys and decreased by a third in girls.
Why diagnosis rates dropped among these young children is unclear. ADHD medication isn’t recommended for children younger than 6, so doctors may be less inclined to diagnose people in this age group, says Mckechnie. “It’s also possible that the waiting list is becoming so long that under-6s have aged past their 6th birthday by the time they’re seen and diagnosed.”
The researchers also found that the number of ADHD diagnoses among both adults and children were almost twice as high in the most deprived areas of the UK compared with the least deprived ones. It is unclear why this is the case, but a variety of genetic and environmental factors could play a role, says Mckechnie. People who are genetically pre-disposed to have ADHD may find that it affects their schooling and careers, which could result in them living in more deprived areas, he says.
Though the findings only go up to 2018, Mckechnie says the rates of ADHD diagnoses are probably even higher now. “In my clinical experience as a GP [general practitioner], requests for ADHD assessments from patients have become much more common since 2020,” he says.