Follow-up of two-year-olds referred for possible autism.

Thirty, 2-year-old children referred for possible autism were evaluated using a parent interview, a rating scale and psychometric tests and reassessed one year later. Clinical diagnosis was relatively stable across time; diagnosis using the formal measures changed significantly, particularly for younger and more developmentally delayed children. Several patterns contributed to the increasing differentiation of children with autism from age 2 to 3, including the development of clearly recognizable, repetitive behaviors in the autistic children and significant improvements in basic social skills in the children judged not to be autistic.