A groundbreaking, Curtin led review of studies involving more than 21 million people worldwide has revealed ADHD impacts more than 3% of the global adult population, putting it on par with several common anxiety disorders such as PTSD and panic attacks.
The review examined 57 unique international primary studies from meta-analyses undertaken between 2009 and 2021 and found it was a global concern, potentially impacting approximately 180 million adults if the ratios are representative.
Lead author Dr Getinet Yaya, from the Curtin School of Population Health, said the umbrella review, published this week in Psychiatry Research, was believed to be the first to quantify how widespread the disorder was internationally.
“It has not only shed light on the significant prevalence of ADHD among adults but also shows the dire need for greater awareness, diagnosis, and management of this condition in adulthood,” she said.
“ADHD is typically associated with children but can affect any age group, and it is imperative we pay more attention to its prevention, identification, and management.
“Several factors contribute to the startling fact that a vast majority of adults are not receiving the appropriate treatment, including limited attention, limited access to specialised care, diagnostic challenges, and variations in treatment options.”
The findings also revealed ADHD-I, characterised by inattention, was the most prevalent subtype among adults, followed by ADHD-HI (hyperactivity) and ADHD-C (combined), supporting past research which has shown that inattentive symptoms of ADHD remained comparatively stable over time while the hyperactive–impulsive symptoms of ADHD were developmentally sensitive, and tended to decrease over time.
“According to the included meta-analytic reviews, the prevalence estimates of ADHD in adults ranged from 2.18% to 5%. Based on a random effect meta-analysis, the pooled prevalence of ADHD in adults was 3.10%, with significant heterogeneity across the studies,” Dr Yaya said.
“This pooled prevalence of ADHD in adults was yielded based on data from five systematic review and meta-analyses studies with a total of 253,528 ADHD cases and 21,142,129 participants.
“This prevalence is comparable or only slightly lower with the reported prevalence estimates of mental disorders that received significant attention by the government across the globe such as schizophrenia (4%), and major depressive disorders (5%).”
The prevalence rates of ADHD were also higher than other well-known mental disorders in adult populations, including bipolar disorders (1%) and some anxiety disorders such as PTSD, OCD, GAD, and panic disorders.
But unlike the aforementioned disorders, ADHD in adults received less attention from health authorities. For example, a 2020 study suggested that only 90% of adults with ADHD receive the intended treatment.
The review also revealed that living in a low socioeconomic environment may contribute to differences in ADHD prevalence.
“Willcutt et al.’s meta-analysis included studies from the US, Iran, Colombia, and Australia, reporting 5.0% prevalence in adults, 1.5 to 2.3 times higher than European studies,” Dr Yaya said.
“Epidemiologic evidence indicates individuals from low SES environments were 1.5–2.3 times more likely to meet ADHD criteria than those from high SES families.”
“This research aims to be a vital resource for policymakers, researchers and clinicians by providing robust and reliable data to help with the development of prevention and early intervention strategies,” Co-author and head of the Curtin School of Population Health, Professor Rosa Alati, said.
“Focusing on ADHD in adults is a critical public health concern, as leaving it untreated can lead to long term social, physical, and mental health challenges.
“By considering the methodological aspects and synthesizing diverse findings, this umbrella review enhances the reliability and generalizability of the prevalence estimates, guiding informed decision making in policy, research, and clinical practice.”