Sex-differential patterns of neuropsychological functioning in adults with attention-deficit/hyperactivity disorder

The sex-differential prevalence of attention-deficit/hyperactivity disorder (ADHD) varies across the lifespan, but little is known about sex differences in executive functions in adults with ADHD. We assessed 261 adults, aged 18–40 years, diagnosed with ADHD (170 males assigned at birth, aged 25.81 ± 5.49; 91 females, aged 27.76 ± 5.42) and 308 neurotypical adults (176 males, aged 24.62 ± 5.14; 132 female, aged 25.37 ± 5.42) via psychiatric interviews to confirm ADHD and other psychiatric diagnoses. They were assessed by the Cambridge Neuropsychological Testing Automated Battery (CANTAB) on Reaction Time (arousal/processing speed), Rapid Visual Information Processing (sustained attention), Spatial Span (spatial memory), Spatial Working Memory, Intradimentional/Extradimensional Shift (set-shifting), and Stocking of Cambridge (spatial planning). The primary analyses were adjusted for age, full-scale IQ, and co-occurring psychiatric conditions. Adults with ADHD had various co-occurring psychiatric conditions without sex differences in ADHD-neurotypical differences. Both adult males and females with ADHD performed poorer in all CANTAB tasks than same-sex neurotypical adults. Significant sex-moderating effects were observed in neuropsychological performance, including greater ADHD-neurotypical differences in arousal for females than males and in location memory for spatial tasks in males than females. There were no sex-moderating effects in the presence of co-occurring psychiatric conditions in adult ADHD. However, there were sex-moderating effects on how ADHD related to neuropsychological functioning in adulthood. ADHD was associated with more challenges in arousal/processing speed in females and more challenges in strategy use or inhibition in spatial memory in males.