The research will help raise awareness of the importance of screening for language disorders when diagnosing ADHD, and vice versa.

In a world-first, MCRI's scientists Hannah Korrel and Emma Sciberras examined the last 35 years of ADHD research and pooled together 21 studies, which included more than 2000 participants. The study was published in the Journal of Child Psychology and Psychiatry.

The study showed that kids with ADHD perform more poorly than children without ADHD across tests for expressive, receptive and pragmatic language skills.

"Until now, it's been difficult to demonstrate that kids with ADHD are more prone to language disorders," Hannah Korrel says.

"Now we can start to look more closely at why this is so, and hopefully, prevent them."

ADHD and language issues often go hand-in-hand. Children with attention issues can have trouble with hyperactivity, impulsivity, inattention and distractibility, all of which can affect language and communication.

"A child with an expressive language disorder may struggle in class because they can't put ideas into a sequence, while a child with a receptive language disorder will have a hard time understanding a teacher's explanation of a task," Hannah explains.

"Pragmatic language disorders are more complicated, and are recognised in the DSM5. This has to do with the ability to use language socially, such as understanding sarcasm, humour, taking turns and other social cues."

Children with ADHD are also more likely to have difficulty socialising, making friends and performing academically, especially in reading and maths. ADHD in adults has been linked to limited employability and even criminality.

"Past research has shown that clinicians are failing to screen children for language disorders when diagnosing ADHD, despite recommendations to do so," Hannah says.

This study will form a basis for future research looking at why a co-occurrence exists between ADHD and language disorders, and whether this is influenced by environment or neurological factors.

Future work will also examine how persistent language problems are for children with ADHD across the primary school years and how the presence of such language problems contributes to long-term outcomes for this vulnerable group.