The spectrum of autism-from neuronal connections to behavioral expression.

Autism spectrum disorders are defined behaviorally by the based on abnormal development in social interaction and communication and restricted, repetitive, and stereotyped patterns of behaviors and interests that are evident before the age of 3. After decades of debate, research has demonstrated that the distinctions among autism, Asperger disorder, and pervasive developmental disorder not otherwise specified are neither clinically reliable nor based on valid neurobiological or genetic differences. The fifth edition of the therefore proposes to collapse all of the clinical syndromes under the single diagnosis of autism spectrum disorder (ASD).