In a large new study from the NIH, researchers found unusual connections in the brains of children with attention deficit hyperactivity disorder (ADHD). In the kids with ADHD, they found atypical wiring between the brain’s frontal cortex and deeper centers in the brain where information is processed. These findings increase our understanding of ADHD, and add biological evidence to help bust persistent myths that blame parents.
ADHD is common in children
Recent statistics show that between 9-10% of children between ages three and seventeen have been diagnosed with ADHD. That diagnosis typically happens around age seven, but may happen earlier in children with more severe symptoms. The early age of presentation, which is a criteria for ADHD diagnosis, and the fact that ADHD has a 74% heritability rate, is additional evidence of ADHD’s biological nature.
Now, this NIH study, which included 10,000 functional brain images, reinforces the reality that children with ADHD are neuroatypical. In other words, the evidence debunks the persistent (but false) myth that “bad parenting” causes ADHD in children.
NIH studies Subcortico-cortical loops in ADHD
There have been many studies to date using functional MRI that have suggested that subcortico-cortical loops in the brain are involved with the development of ADHD. However, these studies have typically been small and have produced inconsistent findings, most likely because they were small.
In this study, by researchers at the NIH’s National Institute of Mental Health (NIMH) and National Human Genome Research Institute, analyzed functional brain images from over 8000 youth with a mean age of around ten and a half years old. They compared the images from 1,696 kids with ADHD diagnoses with those from 6,737 unaffected control subjects.
The researchers were able to confirm the role of subcortico-cortical loops in the brains of children and adolescents with ADHD. They also evaluated a number of possible confounders and found that their results remained robust.
Atypical connections in the ADHD brain
By subcortico-cortical loops, the researchers refer to the increased connectivity they found between deep brain structures and the frontal cortex in young brains with ADHD. Those deep brain structures included the caudate, putamen, and nucleus accumbens seeds deep in the brain where learning, movement and reward are centered. The extra neural connections ran to the frontal cortex of the brain, specifically in the superior temporal gyri, insula, inferior parietal lob, and inferior frontal gyri, where the brain regulates attention and undesirable behaviors.
Why does it matter if there are extra neural connections between the movement, learning and reward centers of the brain and the centers that regulate attention and behavior? Many people would assume that more connection is better. While stronger wiring is good in electronics, the brain relies on just the right amount of connection. Too much leads to atypical function.
Too little neural pruning
One of the key processes that occur in developing brains is called pruning, and it’s the foundation of the brain developing more mature processes. As the brain develops, it prunes, or disposes of the connections between neurons at the synapses. By pruning connectivity it doesn’t need, the brain becomes more efficient.
The finding of increased connectivity between key regions in the young ADHD brain suggests too little synaptic pruning occuring in those pathways. Decreased pruning resulting in increased connectivity between various areas of the brian has been found in the neurodevelopmental disorder of Autism as well.
Hyperfocus and increased brain connectivity
Living with ADHD or parenting children with ADHD comes with many challenges. ADHD can range from mild to very severe an impairing. But it also comes with some benefits often referred to as ADHD superpowers. One of those powers is hyperfocus, which is when a person with ADHD becomes intensely focused on something they find interesting. Hyperfocus brings joy, and can lead people to produce incredible works of science, art, medicine, or in whatever field their interest lies.
Despite the outdated name, attention deficit, it is well established that ADHD is not a deficit of attention, but a dysregulation of attention. With increased neural connectivity between attention centers and reward centers, it makes sense that one of the ways attentional dysregulation shows up in ADHD is the superpower of hyperfocus.
