How Is Autism Diagnosed?

According to the advocacy group Autism Speaks, one in every 36 U.S. children has an autism spectrum disorder (ASD).

Early diagnosis is crucial to helping to treat the condition, but how is a diagnosis done?

The U.S. Centers for Disease Control and Prevention has an updated review of what's involved in diagnosing autism in kids.

"Diagnosing autism spectrum disorder [ASD] can be difficult because there is no medical test, like a blood test, to diagnose the disorder," the agency noted. "Doctors look at the child’s developmental history and behavior to make a diagnosis."

According to the CDC, the time at which a child receives a diagnosis varies. Sometimes an ASD can be detected as young as 18 months, or even before, but only by the age of 2 can a diagnosis by a trained professional be considered reliable.

Unfortunately, in many cases a diagnosis of autism may not come till later in childhood. Some people are unaware that they have an ASD until they are diagnosed as an adult.

Ideally, a reliable diagnosis should take place in childhood, when therapies are most effective, the CDC said.

As children grow, conversations between parents and health care providers that center on kids' skills and abilities should be encouraged, the CDC said.

Tracking your child's development -- how soon they reach typical developmental milestones, for example -- is key. These age-linked milestones include skills observed in playing, learning, speaking, behaving and moving.

Everyone can be part of the "developmental monitoring" process -- parents, grandparents, daycare workers and teachers, can all give feedback on how a child is progressing.

The American Academy of Pediatrics advises that developmental and behavioral screening occur for all children during regular well-child visits at these ages:

• 9 months

• 18 months

• 30 months

When it comes to ASD screening specifically, those should occur at 18 months and 2 years of age, according to AAP recommendations.

Screening can also happen at other times, should a caregiver or a doctor be concerned that a child might have autism, or if a child is at high risk for an ASD (for example, the child has a sibling or other family member with ASD).

A formal evaluation of your child might indicate that early therapeutic interventions for an ASD might be necessary. As well,  the specialist might recommend genetic counseling and testing for your child, the CDC said.

Source: U.S. Centers for Disease Control and Prevention

For more information on child health, check out these additional resources:

Newborn Screening: What It Is, What It Covers and Why It’s Important

Aggression in Kids: What Every Parent Needs to Know

Unexplained Vomiting in a Child: A Doctor Offers Guidance

What Is Croup? Its Symptoms and Treatment