Attention deficit hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder in children and is associated with significant risk of educational failure, interpersonal problems, mental illness, and delinquency. Despite a number of comparative and comprehensive reviews on the effects of ADHD treatments on ADHD core symptoms, evidence synthesizing the effects of ADHD interventions on cognitive difficulties is limited. In this meta-analysis, the neuropsychological effects of non-pharmacological interventions for ADHD were examined across studies published between 1980 and 2017. Data were extracted from studies that used objective cognitive measures (either computerized or pencil-and-paper), and multiple meta-analyses were conducted to compare the effectiveness across these interventions. Publication bias was assessed, as well as quality of the evidence, using Cochrane risk of bias tool for randomized control trials studies. Our final meta-analysis included 18 studies with interventions that were categorized into four categories: neurofeedback, cognitive-behavioral therapy, cognitive training, and physical exercises. Physical exercises demonstrated the highest average effect size (Morris d = 0.93). A further evaluation of cognitive functions yielded 49 effect sizes for the five categories, including attention, inhibition, flexibility, and working memory. Analyses demonstrated a homogenous, medium to large, effect size of improvement across interventions, with inhibition demonstrating the largest average effect size (Morris d = 0.685). This study highlights the positive effect of psychological interventions on ADHD cognitive symptomology and supports the inclusion of non-pharmacological interventions in conjunction with the commonly used pharmacological treatments.
Keywords: ADHD; Cognitive impairment; Executive function; Inhibition; Meta-analysis.
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