Aquatic Exercise as a Complementary Intervention for Cognitive, Behavioral, Motor, and Functional Outcomes in Attention-Deficit/Hyperactivity Disorder, Autism Spectrum Disorder, and Down Syndrome: A Narrative Review

Background: Neurodevelopmental disorders such as attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and Down syndrome (DS) are associated with cognitive, behavioral, motor, and functional impairments that may negatively affect daily functioning and quality of life. Aquatic exercise has emerged as a potential complementary intervention due to its unique physical and sensory characteristics. Objective: To analyze the available evidence regarding aquatic exercise as a complementary intervention for individuals with ADHD, ASD, and DS, considering its potential effects on cognitive, behavioral, motor, and functional outcomes. Methods: A narrative review was conducted using studies identified in PubMed, Scopus, and Web of Science between November 2025 and February 2026. Experimental and quasi-experimental designs, including case studies, evaluating aquatic exercise interventions in individuals with ADHD, ASD, or DS were included. Results: Twenty-two studies were analyzed (ADHD = 7, ASD = 10, DS = 5). In ADHD, aquatic exercise was associated with improvements in inhibitory control, attention, cognitive flexibility, behavioral regulation, academic performance, and cardiorespiratory fitness. In ASD, the main benefits included improvements in balance, motor coordination, aquatic skills, social interaction, communication, adaptive behavior, and behavioral regulation, particularly in Halliwick-based interventions. In DS, positive effects were mainly observed in aerobic capacity, muscular strength, body composition, balance, functional physical fitness, and motor autonomy. Across studies, interventions commonly involved 2–3 weekly sessions lasting 30–90 min over 6–36 weeks. Conclusions: Aquatic exercise appears to be a promising complementary intervention for individuals with ADHD, ASD, and DS, with potential benefits across cognitive, behavioral, motor, and functional domains. Although the available evidence is heterogeneous and methodological limitations remain, aquatic exercise may represent a valuable component of interdisciplinary intervention and adapted physical activity programs.