Impact of early language regression: ADI information on early language regression was available for 49 participants (there was no informant for two participants and the remaining informants could not remember whether regression had occurred). Comparisons between those individuals who did (n = 9) or did not (n = 40) show language regression indicated no group difference in current adult language ratings (Mann–Whitney z = 1.77, p = .08); current IQ (z = .91, p = .36), or decrease in IQ scores over time (z = .85, p = .39).