Language. Changes over time: Language had improved significantly by adulthood with only 5% of the cohort remaining without useful speech (Table 3). Data from the T1-T2-T3 subgroup suggest that most change took place between T1 and T2, when the proportion without speech declined from 27% to 3%. Only four individuals showed deterioration in language over time: two who had been using very few words at T2 were predominantly nonverbal at T3; of two other individuals using spontaneous phrase speech at T2, one was now using mainly brief echoed phrases and the other single words. Three of these four individuals had also shown clinically meaningful decline in IQ from T2 to T3.