Long-term outcomes of toddlers with autism spectrum disorders exposed to short-term intervention

OBJECTIVES: To examine long-term outcomes of toddlers with autism spectrum disorder (ASD) who received a 6-month early intervention at age 2. METHODS: Forty-eight toddlers diagnosed with an ASD received a 6-month evidence-based intervention. Cognitive (IQ) and communication ability, as well as severity of autism symptoms, were assessed by using standardized measures at preintervention (Time 1 [T1]; mean [M] age = 27 months), postintervention (T2; M age = 35 months), short-term follow-up (T3; M age = 41 months), and long-term follow-up (T4; M age = 72 months). RESULTS: From pre- to postintervention, significant gains in IQ and Vineland Communication domain standard scores as well as a reduction in ASD severity were achieved (all P < .01). Between T2 and T3, the 6-month period immediately after completion of the intervention, IQ and Communication scores stabilized and ASD severity increased significantly (P < .05). During the long-term follow-up period (T3-T4), IQ and Communication scores significantly increased again, but ASD severity increased significantly as well (all P < .05). For overall trajectory (T1-T4), robust gains were observed for both IQ and communication; ASD severity did not change. CONCLUSIONS: Findings highlight the potential for positive long-term outcomes in toddlers with ASD. Additional research is needed to understand the relation between early exposure to uninterrupted intervention and developmental gains, and whether initial reduction in ASD symptom severity can be sustained through targeted intervention.