The stability of cognitive and behavioral parameters in autism: a twelve-year prospective study.

Sixty-two autistic patients enrolled in a prospective study an average of 12 years ago. Current retesting results are now available on 53 of the original 62 patients (85.5%). Results indicate that 36 (67.9%) achieved scores within their original IQ group. Twelve (22.6%) moved up IQ groups and five (9.4%) moved down. Of particular clinical importance is the observation that Vineland Adaptive Behavior Scores were consistently lower than cognitive scores, and maladaptive behaviors occurred with equal frequency in the high, medium, and low IQ groups. The implications of this new data for understanding the natural history of autism, educational and vocational planning, and future research are discussed.