Diagnosis of Autism Spectrum Disorder Across the Lifespan

Although autism spectrum disorder (ASD) is one of the most common neurodevelopmental disorders it is also one of the most heterogeneous conditions, making identification and diagnosis complex. The importance of a stable and consistent diagnosis cannot be overstated. An accurate diagnosis is the basis for understanding the individual and establishing an individualized treatment plan. We present those elements that should be included in any assessment for ASD and describe the ways in which ASD typically manifests itself at various developmental stages. The implications and challenges for assessment at different ages and levels of functioning are discussed.