A yearlong training program to help parents communicate with their very young autistic children reduced symptoms of the disorder up to six years later, according to a follow-up analysis released on Wednesday.

Children were less impaired in their ability to communicate, and less likely to show repetitive behavior, one of the telltale signs of the disorder.

They did not, however, show improvements in language skills or reduced anxiety, researchers reported in The Lancet, a leading medical journal.