Just what causes autism?

Swedish climate activist Greta Thunberg, 20, is open about her autism. Actor Anthony Hopkins, 85, disclosed his diagnosis in 2017, and former New York assemblywoman Yuh-Line Niou, 39, the first known autistic woman elected to a state legislature, was diagnosed at the age of 22.

According to a new metastudy in JAMA Network, autism spectrum disorder affects around 2.3% of Americans — more men than women — and presents with a range of abilities and disabilities.

Common early signs and symptoms of ASD appear in the first two years of life and include a lack of response when a child’s name is called, limited use of gestures in communication and lack of imaginative play. Intensive interventions with children under age 5 can improve language, play and social communication significantly.

The causes of ASD are uncertain, but there is some indication that it arises from a blend of genetic predispositions and environmental influences, including possible exposure in utero to certain infections or medications, as well as to chemical toxins found in air pollution and pesticides.

Unfortunately, there is no simple test to diagnose ASD, but if you suspect your child may have neurodevelopmental challenges or is on the spectrum, Autism Speaks has an online, 20-question screening tool that you can fill out and take to your pediatrician for further diagnostic steps. You can access it at www.autismspeaks.org/screen-your-child.

And for physicians, a free, newly validated, 39-question Autism Symptom Dimensions Questionnaire can help arrive at an accurate and useful diagnosis; it’s at https://osf. io/fd5eu.

Health pioneer Michael Roizen, M.D., is chief wellness officer emeritus at the Cleveland Clinic and author of four No. 1 New York Times bestsellers. His next book is “The Great Age Reboot: Cracking the Longevity Code for a Younger Tomorrow.” Do you have a topic Dr. Mike should cover in a future column? If so, please email questions@ GreatAgeReboot.com.