Long-term outcome of a cohort of adults with autism and intellectual disability: A pilot prospective study.

Fusar-Poli et al. (2017) followed the same adults with autism and intellectual disability for ten years. All used little or no speech and lived in a residential facility. Each year staff gave the Vineland Adaptive Behavior Scales. The team wanted to know if daily-living skills would grow, stay flat, or drop.

No extra therapy was added. The study simply watched what happened as time passed.

Raw scores on the Vineland did not budge. Standard scores looked higher, but the authors say that bump is just a test-norming trick, not real skill growth. In plain words: dressing, cooking, and bus-riding skills stayed where they were ten years earlier.

The adults still needed the same level of staff help at the end of the study.

Johnson et al. (2009) seems to disagree. Their autistic adults—who had average IQ—gained adaptive skills and half reached good independence. The gap is explained by IQ: Laura’s group all had intellectual disability while A’s group did not. Same label, different support needs.

Rodgers et al. (2021) pooled 491 preschoolers and found small adaptive gains after two years of intensive ABA. Those kids were very young and not yet labeled with ID. Laura’s adults show what can happen if supports fade after childhood: gains may plateau.

Bak et al. (2019) tracked minimally verbal children for one school year and also saw no spontaneous language growth. Both studies echo the same message—without ongoing, targeted teaching, minimally verbal clients rarely make leaps.

If you serve adults with autism plus ID and little speech, expect adaptive scores to stay flat. Use this fact when you write ISP goals: focus on maintaining, not skyrocketing, skills. Push for lifelong staffing ratios, respite, and community access rather than short-term cure talk. Teach staff to celebrate tiny, day-to-day successes instead of waiting for big jumps that data say are unlikely.