Aim The purpose of this study was to systematically review the neural similarities and differences in brain structure and function, measured by magnetic resonance imaging (MRI), in children with neurodevelopmental disorders that commonly co‐occur to understand if and how they have shared neuronal characteristics. Method Using systematic review methodology, the following databases were comprehensively searched: MEDLINE, EMBASE, CINAHL, CENTRAL, PsycINFO, and ProQuest from the earliest record up to December 2021. Inclusion criteria were (1) peer‐reviewed studies, case reports, or theses; (2) children under 18 years of age with at least one of the following neurodevelopmental disorders: autism spectrum disorder (ASD), attention hyperactivity deficit disorder (ADHD), developmental coordination disorder (DCD), and their co‐occurrence; and (3) studies based on MRI modalities (i.e., structural MRI, diffusion tensor imaging [DTI], and resting‐state fMRI). Thirty‐one studies that met the inclusion criteria were included for quality assessment by two independent reviewers using the Appraisal tool for Cross‐Sectional Studies (AXIS). Results Studies compared brain structure and function of children with DCD and ADHD (n = 6), DCD and ASD (n = 1), ASD and ADHD (n = 17), and various combinations of these co‐occurring conditions (n = 7). Structural neuroimaging (n = 15) was the most commonly reported modality, followed by resting‐state (n = 8), DTI (n = 5), and multimodalities (n = 3). Interpretation Evidence indicated that the neural correlates of the co‐occurring conditions were more widespread and distinct compared to a single diagnosis. The majority of findings (77%) suggested that each neurodevelopmental disorder had more distinct neural correlates than shared neural features, suggesting that each disorder is distinct despite commonly co‐occurring with each other. As the number of papers examining the co‐occurrence of ASD, DCD, and/or ADHD was limited and most findings were not corrected for multiple comparisons, these results must be interpreted with caution.

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