Significant differences in brain activity between children whose attention deficit hyperactivity disorder (ADHD) continues into adolescence and adulthood and those who later grow out of the disorder have been identified by researchers.
Insights from this study by researchers at King’s College London, published in The British Journal of Psychiatry and funded by Action Medical Research, could help researchers develop interventions for individuals with persisting ADHD.
About 1 in 20 children are affected by ADHD, a condition characterised by over-activity, impulsivity and a short attention span. Symptoms of ADHD can cause serious difficulties at school, home and with their peers. Although many children with ADHD continue to have difficulties as adults, others improve and no longer receive the diagnosis in adolescence or adulthood. However, little is known about the differences in brain activity that might exist between these two groups, and the clues these differences may offer concerning how to improve treatment and prognosis for the condition.
For the study, the researchers found a large group of participants diagnosed with ADHD in childhood and their siblings, as well as control sibling pairs. They used a variety of tests to assess brain activity and cognitive ability, including EEG (electroencephalography), which measures brain patterns using non-invasive electrodes placed on the scalp.
The study found that people who had ‘grown out’ of their ADHD (‘remitters’) performed better than those who still had ADHD at follow up (‘persisters’) on a range of tests that measured attention, levels of drowsiness and reaction time. These measures of ‘attentional preparation’ provided markers of recovery and indicated that brain patterns in ADHD remitters were more closely aligned to those of ‘healthy’ controls.
Additional measures of general cognitive ability revealed that ADHD remitters had a higher IQ than ADHD persisters. This difference was already seen during earlier analyses in childhood, which might suggest that IQ acts as a protective factor against ADHD continuing into adulthood.
Although ADHD is also linked to impairments in higher-level cognitive processes (‘executive control’), the study found no significant differences between the two groups in assessments of memory and the ability to inhibit inappropriate responses.
Dr 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. Neurofeedback is based on EEG and works by providing feedback to an individual about their brainwaves and helping them to directly affect their brain function.”
Dr Celeste Cheung, also from the IoPPN, said: “Taken together our findings support a developmental approach to ADHD by showing that improvement over time is possible and that important lessons can be learned by carefully studying those individuals who manage to recover from their ADHD.
"We will next look at the siblings of our cohort, so that we can determine how much the results are due to genes or other shared family factors, and how much are due to environmental experiences that are unique to each individual.”