Screening and diagnosis of autism spectrum disorder in preschool-aged children
Autism spectrum disorder (ASD) is a severe neurodevelopmental disorder that affects 1 in 59 children. Although many early behavioral symptoms of ASD are observable by the first birthday, age of diagnosis remains problematically high, with many children not diagnosed until 3-5 years of age or even later. Appropriate screening and early diagnosis can facilitate early intervention, which has been shown to improve long-term outcomes in children with ASD. This chapter focuses on best practices in screening for and diagnosing ASD in young children. We begin with a discussion of the earliest signs of ASD and early screening practices and challenges. Then, we provide a thorough overview of gold standard diagnostic procedures and measures. We conclude with a discussion on several important considerations involved in diagnosing young children with ASD, including the role of intellectual disability, common comorbid psychiatric disorders, sex differences, and cultural and socioeconomic considerations.