How does having an Autistic sibling affect toddlers?

September 24, 2014August 11, 2023

During my previous employment at the Australian Psychological Society on the early childhood mental health promotion, prevention, and early intervention initiative, KidsMatter Early Childhood, I developed a keen interest in the well-being of children under school age. I discovered that even during toddlerhood, some children begin to show signs of emotional and behavioral difficulties, including “acting out” difficulties such as aggression, and “holding in” difficulties such as excessive worry and anxiety. Whilst some children “grow out of” these difficulties, around 1 in 2 children do not seem to improve without intervention, and continue to show signs of difficulties when followed up in later years.

I was particularly interested in exploring whether the younger siblings of Autistic children might be at higher than usual risk for these sorts of emotional and behavioural difficulties. There are some risk factors for emotional and behavioural difficulties present in this group; an increased risk of emotional and behavioural difficulties in the older sibling who has an Autism diagnosis (e.g., aggression, anxiety), and increased stress and pressure among parents. I discovered that whilst some studies had looked at wellbeing in school-aged siblings of Autistic children, no studies had yet looked at the well-being of younger toddler-aged siblings under 3 years.

To explore this issue I recruited a group of 2-year-old toddlers who had an older Autistic sibling, and followed them from the age of 2 to age 3 and compared their mental health to a group of toddlers who had an older sibling who was developing without concerns. Children were followed up one year later when they were 3-years-old. I found increased rates of “acting out” problems, such as hyperactivity and aggression, and increased rates of “holding in” problems, such as anxiety, in the younger siblings of Autistic children compared to young siblings growing up in a family environment without an Autistic child. Some toddler-aged siblings of Autistic children in the study showed signs of Autism themselves. We found that emotional and behavioural difficulties were more frequent in the siblings with signs of Autism compared to siblings showing few signs of Autism. Further, I found that the more stressed the parents, and the more difficult the behaviour of the older sibling, the more likely the younger sibling also presented with emotional and behavioural difficulties. So, what my research has shown is that siblings of Autistic children are at higher-than-usual risk for emotional and behavioural difficulties, even in toddlerhood. This is important, because it highlights the need to support parents and to address their own stress levels, as well as any behaviour problems presenting in the older sibling, as these may have flow on effects for the younger toddler’s wellbeing and emotional development.

It should be noted that although emotional and behavioural difficulties were more common in the younger siblings of Autistic children compared to in siblings growing up in families without an Autistic child, the majority of siblings of Autistic children were doing well, and were not reported by their parents to be experiencing difficulties. This is the first study of its kind to look at the wellbeing of siblings of Autistic children as young as 2 years old.