Autism impacts normal brain development in areas of social interaction and communication. People with autism may exhibit repetitive behaviors, unusual responses to people, attachment to objects, and resistance to change in routine. The main types of autism are autistic disorder, Asperger's disorder, pervasive developmental disorder, Rett's disorder, and childhood disintegrative disorder, which are distinguished based on levels of impairment and when symptoms begin. While there is no definitive medical test, autism is diagnosed by a team using interviews, observations, and checklists to evaluate social skills, communication, and restricted or repetitive behaviors.