Predicting IQ change in preschoolers with developmental delays.

This study examined IQ change over a 2-year period in 291 young children (mean age 39 months) referred to a pediatric developmental clinic for evaluation of developmental problems. Although correlation between initial and follow-up IQ was very high (0.78), there was also a significant increase in mean IQ score, from 67.12 to 74.06. Moreover, 26% of the subjects showed IQ increase of 16 points or more. Variables making some contribution to IQ change were initial clinical diagnosis, etiology, and intervention. Children diagnosed with a developmental language disorder made significantly greater gains than those diagnosed as mentally retarded. Sex, family status, initial age, and test interval were not significantly correlated with IQ change. We concluded that prediction for individual children is difficult, but that initial diagnosis may be useful in differentially predicting IQ change in young children with developmental delays.