Introduction
Since the earliest follow-up studies of individuals with autism spectrum disorders, it has been evident that two factors -
childhood IQ and the development of functional language - are amongst the strongest predictors of later outcome. However, although most longitudinal studies, especially those involving individuals of normal intelligence, suggest that IQ is relatively stable from childhood to adulthood, this finding is far from consistent. Moreover, the specific factors that predict stability, improvement, or decline in functioning in this group remain uncertain although prognosis tends to be poorer among females, those who develop epilepsy and those with very limited language.