More than 30 percent of fathers of grown children with autism experience symptoms of depression so severe that they warrant clinical attention, first-of-its-kind research indicates.

In a study presented Friday at the International Meeting for Autism Research in San Diego, researchers found that fathers of adolescents and young adults with autism experience high levels of depression and are pessimistic about what the future holds for their son or daughter, much more so than dads whose kids have other disabilities like Down syndrome and fragile X.

“Fathers of adolescents and young adults with autism are really faring the worst,” says Sigan Hartley, a University of Wisconsin-Madison researcher who led the study, which was recently accepted for publication in the journal Family Relations.

Hartley said her findings mirror what researchers already know about mothers of those with autism — that they experience higher stress than other moms and that stress remains even as their children age. But this is the first time anyone has looked at how dads cope as their children get older.

For the study, Hartley and her colleagues looked at self-reported data collected between 2000 and 2005 from fathers of 240 individuals with autism, Down syndrome and fragile X syndrome ranging in age from 10 to their early 20s.

After controlling for the child’s age, family income and the marital status of the father, the research team found that dads of those with Down syndrome fared best out of the three disability groups while those with a child who had fragile X syndrome fell in the middle.

Factors such as the child’s behavior, the likelihood of having more than one child with a disability, the father’s age and the mother’s well-being did seem to play a role in fathers’ experiences. But Hartley says more research needs to be done to better understand what’s leading to elevated levels of depression symptoms in dads of those with autism in particular.

“This is the first step to drawing attention to dads,” Hartley says. “We need to get away from just looking at moms.”