Understanding the relationship between attention deficit hyperactivity disorder (ADHD) and learning disabilities in early childhood

Consider a six-year-old who can't sit still in class and also struggles to read simple words. Is the reading problem a consequence of poor attention, an independent learning disability, or both operating through shared mechanisms? This research investigated the relationship between attention deficit hyperactivity disorder (ADHD) and learning disabilities (LD) in children aged 5 to 8 years in Kuala Lumpur, Malaysia. A case-control design was employed, comparing 142 children diagnosed with ADHD to 131 age- and sex-matched typically developing controls recruited from 8 primary schools and 3 child development clinics between March 2022 and September 2024. Learning disabilities were assessed using the Woodcock-Johnson IV Tests of Achievement (Malay adaptation), and cognitive profiles were evaluated using the WISC-V, NEPSY-II, and the Conners Continuous Performance Test (CPT-3).Among children with ADHD, 61.3% met criteria for at least one learning disability, compared to 21.7% of controls (OR = 5.72, 95% CI: 3.41-9.58, p < 0.001). Reading disability was the most common comorbidity (34.2% in ADHD vs. 11.4% in controls), followed by math disability (27.8% vs. 8.7%) and written expression impairment (21.3% vs. 6.2%). Children with comorbid ADHD and LD showed a distinct cognitive profile characterized by markedly lower phonological awareness (mean = 68.4), sustained attention (71.8), and executive function (73.2) compared to both ADHD-only and control groups. Academic performance was most severely affected in the comorbid group, with reading comprehension scores averaging 28.1 points below controls (p < 0.001). Working memory emerged as the strongest single mediator of the ADHD-LD association, accounting for 34.8% of the indirect effect. These findings support a shared cognitive vulnerability model in which ADHD and LD are connected through common deficits in executive function, working memory, and processing speed, rather than representing entirely independent conditions.