Disparities in treatment initiation following diagnosis of attention-deficit/hyperactivity disorder: a systematic review.

Early intervention improves long-term outcomes in children with Attention-Deficit/Hyperactivity Disorder (ADHD). However, disparities may exist in the timing of treatment initiation following diagnosis. The objective of this systematic review was to examine associations between sociodemographic factors and time to treatment initiation after ADHD diagnosis in children and adolescents. We searched MEDLINE, EMBASE, PsycINFO, and CINAHL from inception to October 8, 2025. We included quantitative studies comparing time to ADHD treatment initiation after a diagnosis across sociodemographic groups, including sex, race and ethnicity, socioeconomic status, insurance type, and geographic factors. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Newcastle-Ottawa Scale. Heterogeneity between studies prevented meta-analysis. We narratively synthesized findings. Twelve out of 6,223 studies initially identified were included in the review. Seven studies reported on pharmacological treatment alone while four studies examined both pharmacological and non-pharmacological treatments; one study reported on psychosocial treatment alone. Sex was the most frequently assessed factor (N = 10 studies), with most studies reporting earlier treatment initiation among males compared with females (effect estimates ranged from 1.02 (95% CI 0.82-1.26) to 1.36 (95% CI 1.21-1.54)). Children from racial and ethnic minority groups, lower-income families, and rural areas generally experienced longer delays in treatment initiation. Findings varied by geographic region, and no consistent differences were observed by insurance type. Sociodemographic disparities persist in the timing of ADHD treatment initiation. These findings may inform strategies to promote equitable and timely ADHD care following diagnosis.