METHOD: A systematic search of PubMed, PsyINFO, CINAHL, EMBASE+EMBASE CLASSIC, ERIC, and Web of Science was conducted for articles up to March 16, 2020. Experimental studies comparing instrumental learning between groups (ADHD versus TD) or a manipulation of reinforcement/medication within an ADHD sample were included. Quality of studies was assessed with an adapted version of the Hombrados and Waddington criteria to assess risk of bias in (quasi-) experimental studies.
RESULTS: A total of 19 studies from among 3,384 non-duplicate screened articles were included. No difference in basic instrumental learning was found between children with ADHD and TD children, nor effects of form or magnitude of reinforcement. Results regarding reinforcement schedule and reversal learning were mixed, but children with ADHD seemed to show deficits in conditional discrimination learning compared to TD children. Methylphenidate improved instrumental learning in children with ADHD. Quality assessment showed poor quality of studies with respect to sample sizes and outcome and missing data reporting.
CONCLUSION: The review identified very few and highly heterogenous studies, with inconsistent findings. No clear deficit was found in instrumental learning under laboratory conditions. Children with ADHD do show deficits in complex forms of learning, that is, conditional discrimination learning. Clearly more research is needed, using more similar task designs and manipulations.
METHOD: Based on a preregistered protocol (PROSPERO: CRD42021239635), PubMed, Web of Knowledge/Science, Ovid MEDLINE, Embase, and APA PsycInfo databases were searched until April 21, 2021, to identify empirical studies reporting indices of autonomic nervous system (ANS) functioning in youths meeting DSM (version III, IV, IV-TR, 5 or 5-TR) or International Classification of Diseases (ICD) (version 9 or 10) criteria for any psychopathological/neurodevelopmental condition and assessed for ED with a validated scale. Eligible outcomes included correlation coefficients between ED and ANS measures or differences in ANS measures between youths with and without ED. Study quality was assessed with the Appraisal tool for Cross-Sectional Studies (AXIS) and the Newcastle-Ottawa Scale (NOS) for cohort studies. Random-effects meta-analyses were used for data synthesis.
RESULTS: There were 12 studies (1,016 participants) included in the descriptive review and 9 studies (567 participants) included in the meta-analyses. No evidence of a significant association between ED and altered cardiac or electrodermal functioning was found. However, exploratory meta-regressions suggested a possible association between reduced resting-state cardiac vagal control and increased ED.
CONCLUSION: This study did not find evidence of an association between ED and autonomic dysfunction. However, preliminary evidence that reduced vagal control at rest might be a transdiagnostic marker of ED in young people was found. Additional studies comparing autonomic measures in youths with and without ED are needed and should also assess the effects of interventions for ED on ANS functioning.
STUDY PREREGISTRATION INFORMATION: Systematic Review and Meta-Analysis: Is Autonomic Nervous System Functioning Atypical in Children and Adolescents With Emotional Dysregulation? https://www.crd.york.ac.uk/prospero/; CRD42021239635.