Regression

In autism, regression means a child loses skills they already had. It's most often words or social behaviors, like looking at faces, sharing smiles and making sounds toward people. It usually happens in the second year of life, and the loss can be sudden or gradual. The American Academy of Pediatrics (AAP) says about 25 percent of children later diagnosed may lose some words, though studies find different rates.

Regression is different from a plateau, where skills stop moving forward but aren't lost. Some autistic children show early differences from infancy instead, and some show a mix. Slow loss can be easy to miss, too. In one study, most parents didn't report a regression even when testing showed their child's social skills had faded. That's why watching for early signs of autism over time matters.

Your child might stop using words they used to say, look at faces less, stop sharing smiles or seem more withdrawn. The Centers for Disease Control and Prevention (CDC) says to act early if your child has lost skills they once had. Talk to your child's doctor right away. Regression also shows up in other conditions, such as Rett syndrome, so a doctor needs to evaluate it. A screening is a starting point, not a diagnosis.

• What changed and when: Ask your child's doctor to look at which skills your child lost, when it started and whether it was sudden or gradual.
• Other causes: Ask whether your child needs testing for other conditions that involve skill loss, such as Rett syndrome.
• If your child is in therapy: Ask your Board Certified Behavior Analyst (BCBA) to share data on any lost skills, so you can bring it to the doctor.