The term attention deficit hyperactivity disorder (ADHD) covers a range of behavioral symptoms, from a short attention span and forgetfulness to excessive physical movement and little sense of danger. Now, the first-ever comprehensive brain-imaging study of the condition in pre-schoolers has shown that kids with ADHD as young as four have structural abnormalities in their brains.
ADHD has suffered a lot of stigma over the years, with many wrongly dismissing it as nothing more than a personality type. However, more and more evidence is showing that there are structural differences in the brains of those who have it.
It’s mainly diagnosed in children, with over 6 million American kids estimated to have it. There appears to be a genetic element to ADHD, as it runs in families, and previous research has found structural oddities in the brains of both children and adults with the condition. But we’re still not sure of the exact cause.
The new research, published in the Journal of the International Neuropsychological Society, suggests that these brain changes start to appear very early on, in children as young as 4 years old. The team looked at 38 normally developing 4 to 5-year-old children and 52 with symptoms of ADHD. They used high-resolution anatomical imaging to build a picture of the children’s brains, and were surprised by what they found.
The brains of kids with ADHD symptoms had significantly less gray matter in certain parts of the brain than those without these symptoms. Gray matter is a kind of tissue found in the brain and spinal cord that’s mainly made up of communicating nerve cells and structures called dendrites, which branch from them. Gray matter volume was most affected in the frontal and left temporal lobes, which are involved in all sorts of things like motor control, problem-solving, memory, impulse control, and language.
Although the differences were noticeable, the researchers think they will probably be more extreme in children with the most severe symptoms. This study focused more on those with moderate symptoms, as the researchers struggled to get children with severe ADHD to keep still during the 30-40-minute brain scan. However, co-lead author Dr Mark Mahone pointed out that they still managed to get 90 percent of the children to keep still for the duration of the scan.
The researchers behind the study plan to follow the pre-schoolers as they age, to see how the structures of their brains might change. Perhaps the differences in gray matter will lessen over time, as previous research has found brain differences to be most pronounced in children with ADHD, in comparison to adults.
Finding out more about the brain differences related to ADHD could help scientists discover more about the condition, and potentially even help them find a cure. At the moment, treatment involves psychological therapies, like cognitive behavioral therapy, and drugs that boost focus while reducing hyperactivity and impulsivity.
"By understanding the brains of children who grow into the disorder as well as those who grow out of it, we can begin to implement targeted, preventative interventions in young children with the goal of reducing adverse outcomes or even reversing the course of this condition," added Dr Mahone.
