A new study suggests that we should start screening children for autism at an earlier age. Children could be diagnosed with autism as early as 14 months, according to a study in the medical journal JAMA Pediatrics.

Autism is a spectrum disorder that may affect social skills, behavior and communication, with guidelines recommending screenings during regular doctor visits at 18 and 24 months. Earlier diagnosis could also mean earlier intervention, which can help children's development.

Dr. David Agus told "CBS This Morning" on Tuesday that early diagnosis of autism spectrum disorder is "paramount." He said that although autism is typically diagnosed at around age 3 or 4 in the U.S., catching it earlier could improve the effectiveness of certain therapies.

"So if you could diagnose it at age 14 months before the connections have been made, it's called plasticity, those connections through behavioral therapy can be stronger," Agus said. "So the hope is that we can influence the brain with behavioral therapy much earlier before those connections really start to kick in so we can actually have better function later in life in these children with autism spectrum disorder."

Agus explained that in this particular study it was easier to detect autism spectrum disorder because of standardized testing starting at 14 months.

"So we had thought that if you start to see delayed behavior in children at an early age, well, we're going to watch until age 2 and 3 to know if it's autism spectrum disorder. In this study, by age 14 months, by doing standardized testing they can actually with 84 percent accuracy diagnose autism," he said.

Only 2 percent of the kids who researchers thought had autism spectrum disorder went on to develop normally and 14 percent ultimately had another developmental disorder.

"This is a very important study and has a lot of optimism for bringing earlier treatment to kids," Agus said.

In terms of the latest data about what causes autism, we still don't know a lot. What we do know definitively is that vaccines do not cause autism, contrary to a lot of misinformation that has contributed to creating one of the largest measles outbreaks in decades.

There is evidence of a "significant genetic association" with autism, and the older the parent is, the higher the likelihood of a child having autism.

"We think it's involved in brain development in the first and second trimester, but that's about it," Agus said.

A separate, small study published recently found autism symptoms dropped by 45 percent for up to two years after patients were treated with a fecal transplant. Agus called the results "amazing."

"What they showed is that most children with autism or adults with autism have either constipation or diarrhea, and in this study they gave antibiotics followed by 7 or 8 weeks of a pill that contained somebody else's bacteria and they showed a 45 percent reduction in the autism symptoms," he said. "So this brings tremendous optimism. You get rid of other biologic issues going on, like the G.I. things, and the brain can function better. So it didn't get rid of the autism disorder but at the same time it dramatically improved symptoms and allowed the children or the adults to function better."