Sex differences in attention-deficit hyperactivity disorder diagnosis and clinical care: a national study of population healthcare records in Wales.

Background: Population-based studies have observed sex biases in the diagnosis and treatment of attention-deficit hyperactivity disorder (ADHD). Females are less likely to be diagnosed or prescribed ADHD medication. This study uses national healthcare records, to investigate sex differences in diagnosis and clinical care in young people with ADHD, particularly regarding recognition and treatment of other mental health conditions.

Methods: The cohort included individuals diagnosed with ADHD, born between 1989 and 2013 and living in Wales between 2000 and 2019. Routine primary and secondary healthcare record data were used to derive diagnoses of ADHD and other neurodevelopmental and mental health conditions, as well as ADHD and antidepressant medications. Demographic variables included ethnicity, socioeconomic deprivation and contact with social services.

Results: There were 16,458 individuals diagnosed with ADHD (20.3% females, ages 3-30 years), with a male-to-female ratio of 3.9:1. Higher ratios (4.8:1) were seen in individuals diagnosed younger (<12 years), with the lowest ratio (1.9:1) in those diagnosed as adults (>18). Males were younger at first recorded ADHD diagnosis (mean = 10.9 vs. 12.6 years), more likely to be prescribed ADHD medication and younger at diagnosis of co-occurring neurodevelopmental conditions. In contrast, females were more likely to receive a diagnosis of anxiety, depression or another mental health condition and to be prescribed antidepressant medications, prior to ADHD diagnosis. These sex differences were largely stable across demographic groups.

Conclusions: This study adds to the evidence base that females with ADHD are experiencing later recognition and treatment of ADHD. The results indicate that this may be partly because of diagnostic overshadowing from other mental health conditions, such as anxiety and depression, or initial misdiagnosis. Further research and dissemination of findings to the public are needed to improve awareness, timely diagnosis and treatment of ADHD in females.