# Mid‐childhood developmental and behavioural outcomes in infants with a family history of autism and/or attention deficit hyperactivity disorder

## TL;DR

This study examines how infants with a family history of autism or ADHD develop by mid-childhood, finding that many develop typically while others show behavioral challenges.

## Contribution

The study identifies distinct developmental and behavioral profiles in mid-childhood for infants with autism or ADHD family history.

## Key findings

- Many infants with a family history of autism or ADHD develop typically by mid-childhood.
- Some children show elevated autism, ADHD, and anxiety traits, often with lower IQ or adaptive functioning.
- Children with autism are found across all profiles but are more common in those with behavioral and developmental challenges.

## Abstract

Prospective studies of autism family history infants primarily report recurrence and predictors of autism at 3 years. Less is known about ADHD family history infants and later childhood outcomes. We characterise profiles of mid‐childhood developmental and behavioural outcomes in infants with a family history of autism and/or ADHD to identify potential support needs and patterns of co‐occurrence across domains.

Two hundred and sixty‐three infants (51% male; N = 198 autism/ADHD family history; N = 65 no family history) were assessed at 6–12 years. A latent profile analysis (LPA) with indicator variables measuring developmental abilities (IQ, adaptive function) and behavioural traits (autism, ADHD, anxiety) identified dimensional, data‐derived outcome classes.

A seven‐class solution was the most robust and clinically meaningful. Two classes (27% and 23%) had typical development; two classes had high autism, ADHD, and anxiety traits—one with low IQ and adaptive function (10%) and one with average IQ but low adaptive function (13%); one class had elevated autism and ADHD but not anxiety traits (10%); and the final two classes had elevated ADHD (9%) and anxiety (8%) traits in isolation. Sex distribution was balanced across all classes. Children with autism were found in all classes but predominantly in the classes with low IQ/adaptive functioning and high behavioural traits, as well as in the class with elevated autism and ADHD traits. We found only partial continuity between membership of similarly derived 3‐year LPA classes and mid‐childhood LPA classes.

Many autism/ADHD family history infants develop typically. However, by mid‐childhood, in addition to those with autism, others show elevated neurodevelopmental (autism, ADHD) and neuropsychiatric (anxiety) behavioural traits. Lower developmental abilities (IQ and adaptive function) are primarily seen in children with an autism diagnosis. Family history infants should be monitored through childhood, and support provided should challenges emerge.