Children who “grow out” of attention deficit hyperactivity disorder (ADHD) have higher IQs than those who do not, a study has shown.

Around one in 20 children are affected by ADHD, a condition characterised by overactivity, impulsivity and a short attention span.

Although many children with ADHD continue to have difficulties as adults, others become free of the problem in adolescence.

Researchers at King’s College London monitored the progress of a group of 110 children with ADHD and carried out a range of tests to assess their brain activity and thinking skills. Those children who grew out of the disorder performed better in tests measuring attention, levels of drowsiness and reaction time. They also had higher IQ scores than ADHD “persisters”.

Jonna Kuntsi, from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London, said: “Our study reveals important differences in brain activity and cognitive performance between individuals who grow out of their ADHD and those whose disorder continues into adolescence and adulthood.

“These findings will guide the development of interventions for ADHD persisters, such as cognitive training and neurofeedback, that directly target those aspects of cognition and brain activity that are linked to ADHD improving over time.”

The findings are published in the British Journal of Psychiatry.