It's great you're looking into the research behind ABA therapy! Studies show that early and intensive ABA (25-40 hours a week) can really help young autistic children. We're talking about improvements in things like cognitive functioning, communication, and adaptive behavior.

One analysis showed that higher intensity ABA led to the biggest gains in areas like IQ and behavior. Even lower amounts of ABA can still be helpful. Starting early, around age 2, seems to be most effective. You can find more info on the Autism Speaks or Association for Behavior Analysis websites.