Some children lose skills they previously developed, such as words, social interaction or everyday abilities. This is known as developmental regression. Regression can occur in children later diagnosed with autism, but it is not itself a diagnosis of autism. When a child loses previously acquired skills, parents should seek professional evaluation rather than assume the change is part of autism.
What Does Developmental Regression Look Like?
Autism regression most often involves a noticeable loss of previously acquired language or social skills. A child who used words may stop using them, respond less often to their name, show less social interaction or lose previously established communication behaviours. Some children may also show changes in play, routines or other abilities.
Research suggests that regression occurs in a proportion of children with autism, although estimates vary depending on how regression is defined. A systematic review found a pooled prevalence of about 30%, with an average reported onset around 20 months.
Parents can review the NICE guidance on developmental regression for information about when further assessment may be needed.
Why Can Skill Loss Happen?
There is no single explanation for developmental regression. Some children with autism show regression as part of their developmental course, while loss of skills can also occur with other medical or neurological conditions. Hearing problems, epilepsy, Rett syndrome and other developmental conditions may need consideration during evaluation.
Regression should therefore be assessed based on the child's complete developmental and medical history.
Does Regression Mean Autism?
Not necessarily. Regression can be one feature seen in children who are later diagnosed with autism, but it does not confirm autism. An autism assessment considers social communication, restricted or repetitive behaviours and developmental history alongside other clinical information.
What Should Parents Do Next?
If a child loses language, social, motor or other previously acquired skills, arrange a prompt evaluation with a paediatrician, developmental paediatrician or paediatric neurologist. NICE specifically recommends specialist referral for children with language or social regression and for children of any age with motor regression.
Parents can record when the changes began, which skills were lost and whether other symptoms appeared. This information can help clinicians plan the assessment.
It is also important not to assume that vaccines caused regression. The WHO's 2026 evidence review found that the strongest available studies do not support a causal relationship between vaccines and autism.
If your child loses previously acquired language, social, motor or other skills, seek prompt professional evaluation.
FAQs
What causes autism regression?
There is no single established cause. Regression may occur in some children later diagnosed with autism, while other medical or neurological conditions can also cause skill loss.
At what age does autism regression happen?
Studies report that regression most often begins during early childhood. One systematic review found an average onset of about 20 months, although individual experiences vary.
What are the early signs of regression?
Loss of previously used words, reduced social interaction, decreased response to communication, changes in play and loss of other previously acquired skills can be signs of regression.
What should I do if my child is regressing?
Contact a paediatrician or qualified developmental specialist promptly. A clinical evaluation can help identify possible developmental, medical or neurological causes.
How long does autism regression last?
There is no fixed duration. The course varies between children, and recovery or development of skills after regression also differs.
Is autism regression caused by vaccines?
Current evidence does not support vaccines as a cause of autism. The WHO's updated evidence review found no causal relationship between vaccination and autism.
Can early intervention help after regression?
Early support can address a child's communication, developmental and functional needs. The appropriate intervention depends on the child's individual assessment and goals.
References
- Prevalence and age of onset of regression in children with autism spectrum disorder: a systematic review and meta-analytical update. Autism Res. 2021PubMed.
- Autism spectrum disorder in under 19s: recognition, referral and diagnosis. NICE guideline CG128. NICE.
- Autism spectrum disorder in under 19s: support and management. NICE guideline CG170. NICE.
- Vaccines, thiomersal and autism spectrum disorder: evidence review 2010-2025. 2026. WHO.
- Autism spectrum disorder: Questions and answers. WHO.