When it comes to autism intervention, new research suggests that more may not always be better.

It’s often recommended that children diagnosed with autism receive 20 to 40 hours per week of intensive interventions, which can include behavioral or developmental approaches.

However, a new analysis factoring data from 144 previous studies involving over 9,000 kids finds that the current advice may be misguided.

“We concluded that there was not rigorous evidence supporting the notion that increasing the amount of intervention produces better intervention outcomes,” said Micheal Sandbank, an assistant professor in the Department of Health Sciences at the University of North Carolina School of Medicine, who led the study published recently in the journal JAMA Pediatrics. “Instead, we recommend that practitioners consider what amount of intervention would be developmentally appropriate for the child and supportive to the family.”

The researchers said that the current guidelines for the amount of intervention children receive stem from a 1987 study, which found that kids with autism who participated in 40 hours each week of behavioral intervention saw greater cognitive improvement than those who had just 10 hours. But, Sandbank noted that subsequent research on this topic has been of questionable quality and has seen varying results.

The new review assessed the amount of intervention children participated in each day and the number of days it was provided. Researchers also controlled for the age of the children, all of whom were 8 or younger. They then considered whether the amount of intervention correlated with a developmental benefit in the children, depending on the type of intervention they received.

Overall, the study found nothing to suggest that more intervention yielded a greater benefit for children with autism.

“There’s probably a minimum amount of intervention needed to provide any benefit at all, and an optimal amount that is dependent on the child,” Sandbank said. “Unfortunately, right now, we don’t have clear evidence as to what that amount should be.”

For now, clinicians should “exercise caution” when recommending intensive interventions, the researchers conclude in the study.

“Although we did not find evidence that increasing amounts of intervention were associated with increasing benefits, this should not be interpreted as evidence that autistic children should be left without support,” the authors wrote. Instead, they said clinicians should work with families to “calibrate individualized supports for autistic children at an intensity that evidences individual benefit without impinging on activities and routines in home, educational and community settings that are important for their thriving.”