Systematic Review and Meta-analysis: The Science of Early-Life Precursors and Interventions for Attention-Deficit/Hyperactivity Disorder.

Abstract

OBJECTIVE\nTo evaluate which early neurocognitive and behavioural precursors are associated with the development of attention-deficit/hyperactivity disorder (ADHD) and whether these are currently targeted in early interventions.\n\n\nMETHOD\nWe conducted two systematic reviews and meta-analyses of empirical studies to examine (1) early-life (0-5 years) neurocognitive and behavioural precursors associated with familial likelihood for ADHD, an early ADHD diagnosis/elevated ADHD symptoms, and/or the presence of later-childhood ADHD, and (2) interventions delivered to children aged 0-5 years targeting the identified precursors or measuring these as outcomes. Standardised mean differences (Hedge s g) and pre-post-treatment change scores (SMD) were computed.\n\n\nRESULTS\nOne-hundred-and-forty-nine studies (165,095 participants) investigating eight neurocognitive and behavioural domains met inclusion criteria for part (1). Multi-level random-effects meta-analyses on 136 studies revealed significant associations between ADHD and poorer cognitive (g=-0.46 [95% CIs:-0.59,-0.33]), motor (g=-0.35 [CIs:-0.48,-0.21]) and language (g=-0.43 [CIs:-0.66,-0.19]) development, social (g=0.23 [CIs:0.03,0.43]) and emotional (g=0.46 [CIs:0.33,0.58]) difficulties, early regulatory (g=0.30 [CIs:0.18,0.43]) and sleep (g=0.29 [CIs:0.14,0.44]) problems, sensory atypicalities (g=0.52[CIs:0.16,0.88]), elevated activity levels (g=0.54 [CIs:0.37,0.72]) and executive function difficulties (g=0.34 [CIs:0.05,0.64] to -0.87 [CIs:-1.35,-0.40]). Thirty-two trials (28 randomised, four non-randomised, 3,848 participants) testing early interventions that targeted the identified precursors met inclusion criteria for part (2). Multi-level random-effects meta-analyses on 22 studies revealed significant intervention-related improvements in ADHD symptoms (SMD=0.43[CIs:0.22,0.64]) and working memory (SMD=0.37[CIs:0.06,0.69]).\n\n\nCONCLUSION\nChildren aged 0-5 years with current or later-emerging ADHD are likely to experience difficulties in multiple neurocognitive/behavioural functions. Early interventions show some effectiveness in reducing ADHD symptoms but their effects on neurocognitive/behavioural difficulties require further study.