The Prevalence of ADHD Subtypes Significantly Differ by Sex

Among individuals with attention-deficit/hyperactivity disorder (ADHD), the diagnosis of ADHD subtypes significantly differs by sex – as girls and women are more likely to be diagnosed with predominantly inattentive ADHD while boys and men are more likely to be diagnosed with combined-type or predominantly hyperactive ADHD. These study findings were published in the Journal of Attention Disorders.

Previous research has demonstrated significant sex differences in the diagnosis, symptom trajectory, and comorbidities of ADHD. However, relatively little is known about the prevalence of ADHD subtypes between girls/women and boys/men. To this aim, the current study aimed to provide further insight into the potential sex differences in the timing of initial ADHD diagnosis, prevalence of ADHD subtypes, and comorbid depression and/or anxiety.

Researchers conducted a retrospective, observational study using data from 4 United States databases, including 3 administrative claims databases and 1 electronic health record database. The databases were selected to provide a demographically comprehensive cross-section of the US population. Participants had received an initial diagnosis or procedure indicating the presence of ADHD (index date) on or after October 1, 2015. The researchers evaluated 9 cohorts of patients, which included patients with all types of ADHD, predominantly inattentive ADHD, hyperactive-impulsive ADHD, combined-type ADHD, other/non-classified ADHD, patients with major depressive disorder (MDD), patients with anxiety, patients taking antidepressants, and patients taking anxiolytics. Additionally, results were further stratified by sex and age category (<12, 12–17, and ≥18 years).

The researchers found that ADHD diagnoses were more prevalent among boys/men than girls/men for individuals younger than 12 years of age and those aged 12 to 17 years across all age groups. However, the prevalence of ADHD was higher among girls/women than boys/men in the subgroup of participants aged 18 years and older, as the mean age at initial ADHD diagnosis was higher for girls/women (range: 16.3-28.6 years) than boys/men (range: 11.2-22.7 years).

Sex differences were also observed in the prevalence of ADHD subtypes. Girls/women were more likely to be diagnosed with predominantly inattentive ADHD (standardized mean difference [SMD], 0.14 to 0.23) while boys/men were more likely to be diagnosed with combined-type ADHD (SMD, -0.14 to -0.20) and hyperactive-impulsive ADHD (SMD, -0.09 to -0.08).

In addition, girls/women were approximately twice as likely to have a diagnosis of depression or anxiety in the year before their initial ADHD diagnosis, relative to boys/men. Girls/women were also more likely than boys/men to receive new diagnoses and/or treatments for depression or anxiety in the year after their initial ADHD diagnosis. The sex differences observed in diagnoses and treatment for depression or anxiety were most pronounced in the subgroup of individuals aged 12 to 17 years.

“Awareness of these differences between the sexes is important for clinicians in order to facilitate consideration of whether [girls and women] diagnosed with depression or anxiety may have comorbid ADHD, and vice versa,” the researchers concluded. “Additional research is required to further identify the contributing factors and the impact on the diagnosis and care of [girls and women with] ADHD.”

The primary study limitation is the use of secondary data from healthcare databases not primarily used for research. Additionally, the information acquired on the index date was used to assign patients to ADHD subtypes; however, this subtype may have been misdiagnosed, not known at the time of their ADHD diagnosis, or may have changed over time. 

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of author disclosures.

This article originally appeared on Psychiatry Advisor