ADHD diagnoses and prescriptions have increased significantly in the UK over the past 2 decades, except in children under 5 years of age, according to a study in BJPsych Open.
Researchers from University College London performed a meta-analysis using IQVIA Medical Research Data on more than 7.6 million people aged 3 to 99 years to estimate incidence and prevalence of ADHD diagnoses and prescriptions in UK adults and children in primary care. The data was analysed by age, gender, social deprivation status, and calendar year.
The researchers identified that 0.5% (35,877 individuals) had a diagnosis of ADHD, and 0.2% (18,518) received at least two prescriptions within a year for ADHD medications from primary care.
“Except among 3- to 5-year-olds, the incidence and prevalence of ADHD diagnoses and prescriptions has increased from 2000 to 2018 in all age groups,” they said.
The rate of new ADHD diagnoses increased from 2000 to 2018 in both males and females, and by 2018, the proportion of ADHD diagnoses was 255 per 10,000 in boys and 67.7 per 10,000 in girls. For adults, it was 74.3 per 10,000 in men and 20 per 10,000 in women.
The rate was found to have doubled in males aged under 18 years and increased nearly 20-fold in those aged over 18 years. In females, the rate quadrupled in those aged under 18 years and increased 15-fold in those aged over 18 years, the researchers found.
In children, new diagnosis rates were highest between 6 and 9 years of age, whereas in adults new diagnosis rates were highest between 18 and 29 years of age.
Risk of ADHD Healthcare Inequality
New diagnosis rates were highest in the most deprived areas for children and adults — approximately two- to three-fold higher in the most deprived areas versus the least deprived areas. Similar patterns were also seen for first prescriptions of ADHD medication use.
“Many people are accessing private care for ADHD," according to lead author Dr Doug McKechnie, from UCL's Institute of Epidemiology and Health Care, who said that this could "create healthcare inequalities, given that ADHD is more common in deprived areas". Furthermore, "If people in deprived areas are struggling to get diagnosed with ADHD, our results may actually under-estimate how many people there have it, as we only counted diagnosed ADHD", he added.
As for prescriptions, the rates were 156 per 10,000 in boys, 36.8 per 10,000 in girls, 13.3 per 10,000 in men and 4.5 per 10,000 in women, the researchers calculated.
Relative Increase Largest Amongst Adults
The findings showed that, "in absolute terms, the increase was highest in children," explained the authors. Amongst boys aged 10-16 years, 1.4% had an ADHD diagnosis and 0.6% had been prescribed ADHD medication in 2000. By 2018, that was the case for more than double the number (3.5%) and four times as many (2.4%), respectively.
However, the relative increase was "largest among adults", the researchers found. Over that time, there was approximately a "twenty-fold" increase in ADHD diagnoses and "nearly fifty-fold" in ADHD prescriptions in men between the ages of 18-29 — from 0.01% to 0.56%.
Dr McKechnie emphasised that whilst ADHD was "most likely" to be diagnosed in childhood, an increasing number of people are diagnosed for the first time in adulthood. "We do not know exactly why this is happening, but it may be that ADHD has become better recognised and diagnosed," he said.
Unprecedented Rise in Demand for Support
Dr McKechnie said GPs, who already face many demands on their time, need better support in prescribing and monitoring ADHD medications "as rates and awareness of ADHD increase — allowing patients to receive prompt, safe, and effective care".
Dr Peter Carpenter, chair of the Royal College of Psychiatrists’ Neurodevelopmental Special Interest Group, commented that although it was "good to see public awareness of ADHD had grown", and that more people were coming forward for a diagnostic assessment and treatment, NHS mental health and primary care services must be provided with the necessary resources to meet this "unprecedented rise in demand for support".
The authors stress that adult ADHD services in particular are in "dire need" of appropriate resourcing.
"Only with proper funding will they be able to effectively manage growing waiting lists for assessments and provide timely and high-quality post-diagnostic care to those who need it," Dr Carpenter underlined.
BJPsych Open. Published online 17 July 2023. Full text