A new government report confirms what many parents of teens with autism have long suspected: There is little scientific evidence backing up the current treatments used for autism spectrum disorders in older children and young adults.

"What we found was a dramatic lack of evidence for any kind of interventions," said Julie Lounds Taylor, an assistant professor of pediatrics and special education at Vanderbilt University and lead author of the paper.

"It was not a surprise," Taylor continued. "There's not very much research in general focused on adolescents and adults with autism."

According to the Centers for Disease Control and Prevention, approximately 1 in 88 children have been diagnosed with autism spectrum disorder by the time they're 8 years old, and most children are diagnosed around age 4. With treatment, the core symptoms of autism -- such as problems with communication and social interaction -- can improve. However, "some degree of impairment typically remains throughout the lifespan," the new report states.

To summarize the current evidence, Taylor and her colleagues combed through scientific databases for studies analyzing the various treatments and interventions available for people between 13 and 30 years old with autism. Due to inadequate sample sizes or lack of "relevance to ASD treatment," only 32 studies warranted analysis. Of those 32 studies, most "were poor quality," according to the researchers.

The researchers found only eight studies on medical interventions that met their criteria for inclusion, half of which were considered "fair quality" and half of which were considered "poor." Studies looking at the use of antipsychotic medications to reduce behavioral problems that can accompany autism showed some benefits, such as reductions in repetitive behavior, aggression, hyperactivity and irritability.

Serotonin reuptake inhibitors, a widely used antidepressant type, also appeared to curb irritability, aggression and repetitive behavior, according to the studies. However, all of the research looking at the use of medication to treat autism in teens found side effects, such as weight gain and fatigue.

"The FDA-approved medications for autism address associated symptoms, such as irritability, but none address the core symptoms of autism," said Geraldine Dawson, chief science officer for Autism Speaks, one of the largest autism advocacy organizations in the country. "There is great need for more research focused on developing medicines that can improve the lives of people with autism."

The new report also considered the strength of studies focused on non-drug-related interventions for autism, including educational programs and intensive behavioral treatment. None had sufficient evidence to clearly prove or disprove their efficacy. A section of the report focused on vocational programs aimed at helping young adults with autism get into the workforce and stay there was published in the journal Pediatrics on Monday; it also found there was too little evidence to say whether such programs can truly be effective.

"There is a tremendous knowledge gap regarding how to help young people with autism be successful in the work environment," Dawson told The Huffington Post. "Given the huge number of adolescents who will be entering adulthood in the next several years, it is crucial that we address this knowledge gap."

There is no cure for autism, and much of the research thus far has focused on therapies for younger children.

"Until recently, we have thought about autism as a childhood disorder, and there has been quite a lot of research thinking about early interventions," Taylor, the lead author, told HuffPost. "It's only in the last five to 10 years that [researchers] have started to think about the fact that children with autism grow up to be adults with autism."

She predicted that in the next 10 to 20 years, more funding will go toward studying treatments for teens and adults with autism and that researchers will start to have a much better sense of which treatments work.

In the meantime, she said parents of teens with autism or children who will soon enter their teenage years should not lose hope.

"What we can say to families now is keep doing what you're doing, keep exploring what's out there and finding what works for you," Taylor said. "We didn't find evidence saying that these things don't work; we just don't have enough evidence to conclude that they do."

Sallie J. Rogers, a professor of psychiatry and behavioral sciences at the University of California Davis MIND Institute, encouraged parents to push for more research.

"One things parents can do is make a fuss about the relative lack of study of teens and adults, because people are adults for most of their lives. They're only toddlers for two years." Rogers said. "The problems of adolescents and adults should be primary, and parents have a lot of power."