Lost words or skills: preparing for an assessment

Your child had words. "Mama", "ball", "bye-bye", maybe ten of them. Or they used to wave and look at you when you came into the room. Then those things faded. Whatever the cause turns out to be, a change like this is worth describing to a health professional rather than explaining away. This page helps you note what changed and ask the right questions.

What "regression" means

Regression is the loss of skills a child already had. In young children it can show up as:

• Words disappearing. Words your child used to say become rare or stop.
• Gestures fading. Waving, pointing or reaching to be picked up happen less.
• Social engagement dimming. Less turning to their name, less interest in shared games like peek-a-boo.
• Play changing. Copying or pretend play stops or becomes less frequent.

The Public Health Agency of Canada lists "starting to develop language skills but then stopping or losing those skills" among the signs of autism to watch for. ¹ These examples are not a diagnostic test.

Why to ask for an opinion

A large review that pooled 85 studies and more than 29,000 children found regression reported in roughly a third of autistic children, with an average onset around 21 months. ² Definitions and the skills studied varied; these figures do not predict your child's path.

Losing a skill your child had is different from developing more slowly. Describe the change without waiting until you can explain it.

In Canada the median age of autism diagnosis is 3.7 years. ³ That figure comes from a different population than the regression studies, so it does not show that any particular step will shorten a wait by a set amount.

What regression does not tell you

A study of more than two million children across five countries estimated autism heritability at about 80 percent. This is a population estimate; it does not explain why a particular child lost skills. ⁴

A cohort followed from infancy into mid-childhood describes developmental profiles that change over time. ⁵ It does not establish how likely a child is to regain words after regression. The sources here cannot promise whether, or when, a child will regain a given skill.

Regression is not always linked to autism. Hearing differences and some medical situations can also be involved. An assessment is needed to look for the cause; this page cannot determine it from a distance.

When to contact a doctor promptly

Contact your doctor or call Info-Santé 811 promptly, without waiting for a routine appointment, if you notice:

• a sudden loss of skills, over a few days;
• staring spells, unusual movements or possible seizures;
• a loss of skills after age 3, especially in several areas;
• a loss of motor skills, such as walking or using the hands.

If your child is having a seizure, is hard to wake, or you are worried about their immediate safety, call 911.

Do not wait to see if these settle. Ask for guidance suited to the situation; a professional will decide which tests are appropriate, which may include hearing or a specialized assessment.

What to do in Quebec

• Write down what you see. The words or skills your child used to have, roughly when, and what has changed recently. Photos or videos you already have can help you describe it; keep them private.
• Contact your doctor or your CLSC. You can say: "My child no longer uses some skills they had learned. Which assessment do you recommend? Could you note these changes in the file?" See What to say to your doctor.
• Ask about Agir tôt. According to the program's page, it is free and voluntary, for children under 7, and does not require a diagnosis. ⁶
• Discuss screening. Ask whether the M-CHAT-R/F suits your child's age and situation; it does not replace an assessment of the lost skills. See M-CHAT-R/F explained.

While you wait, adapt talk and play to your child's pace. Discuss which ways of communicating might help, including gestures, pictures or signs. See AAC and signs do not delay speech and Waiting is not wait-and-see. These suggestions do not replace individual advice.

This week

Sources

1. Autism: Signs and characteristics (2026) ↩1
2. Prevalence and onset of regression within autism spectrum disorders: a meta-analytic review (2013) ↩1
3. Autism spectrum disorder: Highlights from the 2019 Canadian Health Survey on Children and Youth (2022) ↩1
4. Association of genetic and environmental factors with autism in a 5-country cohort (2019) ↩1
5. Mid-childhood developmental and behavioural outcomes in infants with a family history of autism and/or ADHD (2026) ↩1
6. Agir tôt program (2026) ↩1