This chapter identifi es the biological underpinnings, phenomenology, assessment and medical treatment of Autism Spectrum Disorder, a complex neurodevelopmental disorder. Basic science has made great strides in identifying the brain pathology of autism at various levels of scrutiny. This chapter reviews genetic, molecular, histological, anatomical and epidemiological levels of the disorder. Also, new assessment technologies have come on line to provide greater clarity in what collection of observations should be called autism and what would not. Although interventions that alter the newly identifi ed pathophysiological processes are yet to be formulated, approaches to treatment that fail to take into account the current scientifi c evidence of the causes of autism can and should be avoided. The chapter describes an orientation to autism from the perspective of the scientifi c literature to provide a foundation for clinical decision-making for the practitioner.
IntroductionHow we evaluate, diagnose and treat autism is changing rapidly. Diagnostic and Statistical Manual 5 essentially eliminates autism as a discrete diagnostic entity and consistent with other neurodevelopmental disorders creates a continuum ( 1 ). Autism Spectrum Disorder (ASD) is one of twenty six diagnostic codes collected under the larger rubric of neurodevelopmental disorders in the American Psychiatric Association's newest diagnostic compendium. The diversity of disorders included span intellectual disability, Attention Defi cit Hyperactivity Disorder as well as learning disorders and motor disorders including Tic disorders.ASD can be plotted along a continuum of the essential ingredients of the original concept, now sixty years old, of Kanner's Autistic Disturbances of Affective Contact ( 2 ). Defi cits of emotional reciprocity and nonverbal communication and the narrow interests of the individual with autism remain. The distinction for DSM-5 from its predecessor is the constriction of the richness of the menu of criteria.Left as historical footnotes are the archaic views of causes now replaced by rich and exciting scientifi c data. This growing body of empirical research quickly moves the frontier of our understanding of the disorder and re-defi nes the medical basis of ASD. This chapter discusses some of the newer studies that have implications for our medical approach to the syndrome. Going forward, new research will need to validate whether fi ndings from studies of a forme fruste or lesser variants are equally relevant to its most severe form. Studies with subjects that are more compliant because they are on the higher end of the spectrum and can participate may produce data that can generalize to the entire spectrum. Research however, on brain tissue collected under previous diagnostic taxonomies may not be valid to the entire range represented by ASD.One gets a sense from recent provocative fi ndings in genetics, immunology and neurochemistry that the fi eld is much further along towards a comprehensive view of etiologies and ...