A new study led by Stony Brook University suggests that autism may not be a single spectrum, but rather several interrelated spectra. The researchers compared two large samples of children and adolescents, both with and without diagnosed autism, and found that autism is comprised of three related domains of atypical behavior: social interaction difficulties, interpersonal communications difficulties, and repetitive or restrictive thoughts or actions. Each of these domains can vary in severity from mild to severe. The researchers believe that this new understanding of autism could have significant implications for how professionals classify and support individuals with autism. The study was supported by grants from the National Institute of Mental Health and the Simons Foundation Autism Research Initiative.