The negative impact of neurodevelopmental disorders and multiple co-occurring conditions on academic performance of school-age children and adolescents.

Students with neurodevelopmental disorders (ND) are at risk for academic impairment. However, the pervasive co-occurrence among these conditions has rarely been considered when evaluating this association. This study examined whether intellectual disabilities (ID), communication disorders, autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), specific learning disorder (SLD), and motor disorders were related to academic outcomes. Parents and teachers completed standardized screening instruments for mental health problems and learning difficulties. Children who screened positive were interviewed for diagnostic confirmation according to the Diagnostic and Statistical Manual of Mental Disorders, while students who screened negative served as controls. Academic performance across multiple subjects was obtained from school records. The final sample comprised 9018 participants aged 5-17. Mixed-effects ordinal logistic regression models determined the independent and combined effects of ND on academic performance, adjusting for background and coexisting conditions. When examined separately, each diagnostic category was significantly associated with lower marks in all educational outcomes, even after adjusting for sociodemographic and school-related factors. However, when the influence of neurodevelopmental co-occurrence was controlled for, ID emerged as the strongest predictor of poor academic performance, followed by ADHD, SLD, and communication disorders. ASD and motor disorders were only associated with lower marks in arts and physical education. Furthermore, youth with coexisting conditions were at higher risk for academic impairment across all subjects. These findings highlight the need for early diagnosis and targeted interventions to address the specific educational needs of students with ND. Likewise, co-occurring diagnoses should be actively sought to avoid disadvantaging children with multiple disorders.