Describes the differences between the previous Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), and the current one (DSM-5) in terms of how autism, autism spectrum disorder (ASD) and related disorders are viewed and diagnosed. Identifies the physiological, familial, and psychological issues in the clinical diagnosis of autism spectrum disorder. Addresses the issues of toxicity from heavy metal (mercury, lead) and other pathogenic factors in the development of autism spectrum disorder. Identifies medications used in management of various clinical resentations and comorbidities of autism spectrum disorder. Discusses appropriate nonpharmacological (general health, psychological, and behavioral) approaches to the treatment of autism spectrum disorder.