The group of disorders that formerly included autism, pervasive developmental disorder, not otherwise specified (PDD-NOS), Asperger's syndrome, and sometimes Rett's disorder and childhood integrative disorder are are now referred to as autism spectrum disorders. The range of these disorders varies from severely impaired individuals that were formerly described as suffering from autism to other, more high-functioning individuals who have abnormalities of social interaction but normal intelligence, who were described as having Asperger's syndrome. The ways in which autism spectrum disorders are exhibited can differ greatly. Additionally, autism can be found in association with other disorders such as mental retardation and certain medical conditions. The degree of autism can range from mild to severe. Mildly affected individuals may appear very close to normal. Severely afflicted individuals may have an extreme intellectual disability and be unable to function in almost any setting.