The majority of teens with autism lack contact with friends outside of school, saying they are never called or invited to social activities, according to a new study.

The research looked at data from more than 11,000 middle and high school-age students in special education and found that teens with autism — especially those who struggle with conversational skills — are significantly less likely than their peers to spend time with friends or report having a social life.

Nearly half of the students with autism said they never saw friends outside of school. Meanwhile, most indicated they don’t get calls from friends and are not invited to hang out.

The social struggles experienced by adolescents with autism were more pronounced even when compared to those with intellectual disabilities, learning disabilities and speech impairments, according to the study published this month in the journal PLoS ONE.

“It appears that experiences with peers are more likely to occur one-on-one, and perhaps at home rather than in the community,” said Paul Shattuck, an assistant professor of social work at Washington University in St. Louis, who led the study.

Exaggerating the situation is the fact that only about 1 in 3 teens with autism participates in a club, sport or other group activity, the study found. And when these adolescents are participating with a group, it’s more likely to be with others who also have special needs rather than in an inclusive environment.

Shattuck and his colleagues said that such limited social contact is concerning, as it can trigger health consequences. They say the study findings suggest that researchers and autism specialists need to do more to foster opportunities for socialization and find ways to help young people with the disorder learn to interact with friends.