<p>Youngest children in their class with ADHD are just as likely to keep the diagnosis when enter adulthood as older pupils in their year group.</p>

<p>In the past, scientists have questioned the validity of ADHD in younger pupils, arguing they are only diagnosed because they are less mature than their peers.</p>

<p>But this Lancet Psychiatry study shows for first time that these children are no more likely to lose ADHD over time than those born towards the start of the school year.</p>