Physical cause may be at root of ADHD
ADHD is a brain disorder and should not be used as a convenient label for difficult children or poor parenting, concludes the first major physical study of it.
Researchers analysed the brain volumes of more than 3 200 people and noticed that patients with attention-deficit hyperactivity disorder, or ADHD, were underdeveloped in five key regions.
Areas governing emotion and motivation were found to be smaller than in the general population, regardless of whether the participants were on medication.
The scientists behind the study, which is published in The Lancet journal, say their findings prove for the first time that the condition has a physical cause.
About one in 20 children under the age of 18 are affected by the disorder, which is characterised by impulsive behaviour, inattention and hyperactivity. Two thirds of children affected continue to experience symptoms in adulthood.
Last year, a separate study found the condition was being vastly over-diagnosed and often used as a slapdash term for a collection of behavioural problems, as well as immaturity.
Researchers have suspected for some time that “real” ADHD patients have different brain shapes to normal people of the same age.
However, previous studies have been too small to prove the hypothesis.
Dr Martine Hoogman, who led the new research at Radboud University in Nijmegen in the Netherlands, said: “The results from our study confirm that people with ADHD have differences in their brain structure and therefore suggest that ADHD is a disorder of the brain.
“We hope that this will help to reduce stigma that ADHD is just a label for difficult children or caused by poor parenting.”
The international team of researchers measured the differences in the brain structure of 1 713 people with a diagnosis of ADHD and 1 529 without, all aged between four and 63.
All 3 242 people had an MRI scan to measure their overall brain volume, as well as the size in seven regions thought to be linked to ADHD.
Among the regions found to be underdeveloped in the case of ADHD patients was the hippocampus, which may contribute to the disorder through its role regulating emotion and motivation, The Lancet study said.
Prescriptions for drugs such as Ritalin for children diagnosed with ADHD are thought to have doubled in the past decade.
The causes of ADHD are not known. However, the condition has been shown to run in families.
Premature birth, or being born to a mother who smoked, or abused drugs or alcohol during pregnancy, may also be contributory factors, it has been suggested. — The Daily Telegraph