Signs of Autism: Symptoms at Every Age

Early signs in infants include limited eye contact, not smiling back by 6 months, not babbling by 12 months, not responding to their name by 12 months, and not pointing or waving by 12 months. By 16–18 months, not saying single words is also a red flag. The Canadian Paediatric Society recommends discussing these concerns with your doctor promptly.

Toddler signs include no two-word phrases by 24 months, loss of previously acquired language skills, limited pretend play, repetitive movements (hand flapping, rocking), lining up objects, unusual attachment to specific objects, intense distress at changes in routine, and limited interest in other children.

School-age children may have difficulty understanding social rules, struggle to maintain friendships, experience sensory overload in busy environments, have very focused areas of intense interest, and find transitions or unexpected changes very difficult. Academic skills may be strong in some areas and challenging in others.

Autistic adults may find social interactions exhausting, struggle to read implicit social cues, prefer direct communication, have strong routines and difficulty with unexpected changes, experience sensory sensitivities, and have intense areas of interest. Many adults are not diagnosed until adulthood, particularly women who have learned to mask their traits.

Girls often present with stronger social motivation and are more likely to "mask" autism traits by imitating social behaviours learned from peers. This camouflaging can make autism less apparent to parents and clinicians, leading to later diagnosis. Girls may show fewer repetitive behaviours and more internalized anxiety, making their presentations more subtle.