In a landmark study, researchers have found that in children diagnosed with autism by 18 months old, therapy can help to raise IQ levels and improve behavior and language development.

“Early intervention can be very effective for toddlers with autism,” says Geraldine Dawson, chief science officer of the advocacy group Autism Speaks, and one of the two lead authors of a study published Monday in the journal Pediatrics.

Pediatricians have been screening 1 – 2 year old children for autism for years, however treatment at such a young age hadn’t been clear.

“It’s crucial, if we’re going to offer screening at such a young age, that we can offer an intervention, and now we know we have methods that are effective,” says Dawson.