The Role of Diagnostic Instruments in Dual and Differential Diagnosis in Autism Spectrum Disorder Across the Lifespan

The heterogeneity inherent in autism spectrum disorder (ASD) makes the identification and diagnosis of ASD complex. We survey a large number of diagnostic tools, including screeners and tools designed for in-depth assessment. We also discuss the challenges presented by overlapping symptomatology between ASD and other disorders and the need to determine whether a diagnosis of ASD or another diagnosis best explains the individual's symptoms. We conclude with a call to action for the next steps necessary for meeting the diagnostic challenges presented here to improve the diagnostic process and to help understand each individual's particular ASD profile.