Autism: From Behavioral Syndrome to Systemic Biological Disorder—Communication I: Beyond Kanner’s Behavioral Diagnosis Toward a Biological Framework for Autism

Autism spectrum disorder (ASD) is usually diagnosed by looking at behavioral and developmental traits. This approach helps identify the autistic profile, describe strengths and challenges, set clinical baselines, and monitor changes. Still, focusing only on behavior does not explain the biological reasons for how autistic features appear, change, or improve. Studies in genetics, neuroscience, immunology, microbiology, mitochondrial biology, and metabolomics show that autism involves many complex and interacting processes. These include immune and inflammatory regulation, gut health and the microbiome, mitochondrial and metabolic function, oxidative balance, neural signaling, and more. There is no single cause or set of abnormalities that applies to all autistic people. Similar behaviors can come from different biological factors, which may change as a person grows. Autism should be seen as a dynamic biological process, a behavioral syndrome, or a set of fixed biological factors that interact with changing physiological states, health, environment, and treatment. Diagnosis should combine behavioral and developmental information with ongoing, broad biological assessment, while avoiding the early use of unproven biomarkers in clinical care. This approach can help separate stable risk factors from those that can be changed, identify key patterns, and clarify how different biological systems relate to clinical symptoms. Future treatments should look beyond behavior and focus on proven, mechanism-based strategies tailored to each person’s biology as it changes over time. Considering biological mechanisms alongside observed traits may improve long-term assessment, biomarker validation, treatment, and precision medicine in autism.