ADHD News & Research

Study: Scans Show Marked Differences in the Brains of Preschoolers with ADHD

Children with ADHD show significant neurological differences by the age of 4, according to studies of a collection of brain scans that provide new insight into the origins — and development — of attention deficit.

March 29, 2018

The brains of children and adults with attention deficit hyperactivity disorder (ADHD) look different from those of their non-ADHD counterparts. Researchers have long known this; however, they hadn’t yet pinpointed when exactly those changes started taking shape.

Now, a new study1 finds that children as young as 4 who show symptoms of ADHD have markedly different brain scans than do their peers — information that will help researchers better understand the long-term developmental trajectory of ADHD, the study’s authors said.

The study, published this week in the Journal of the International Neuropsychological Society, conducted MRI brain scans on 90 children aged either 4 or 5 years old. Slightly more than half of the children had been diagnosed with ADHD; the remaining children served as controls, and were matched by race, socioeconomic status, gender, and IQ to the children with diagnosed ADHD. None of the children, from either group, had ever taken ADHD medication.

The scans showed significant, structural differences in the brains of children with ADHD, the researchers said. Their brains were smaller, overall, with smaller frontal and temporal lobes in particular. The size differences were directly correlated with symptom severity, with the most hyperactive or inattentive children showing the greatest size disparities in overall brain volume and in lobe size.

“Something about what is happening in early life leads them to have differences in their brains even by age 4,” said lead author Mark Mahone, Ph.D., in an interview with the New York Times. “There are structural differences in brain volumes, there are connections between brain regions reflected in white matter changes in people with ADHD, there are chemical changes in some of the major transmitter systems in the brain. When the brain is asked to do something, the brains of children with ADHD do the same task, but the brain is less efficient.”

The study was observational, and was thus not able to determine what caused the children’s brains to develop differently, or which brain areas correlate to which symptoms. But the researchers intend to follow the children, they said, repeating the brain scans periodically, to better understand how ADHD brains develop throughout a lifetime.

“We’re betting some of [the preschoolers with ADHD] are going to grow out of it,” Mahone said, while some of the control children may develop symptoms later on. The data gathered will help future studies better understand the benefits of early intervention and diagnosis, he said, and perhaps make them better able to answer questions parents grapple with, like: “If we had started a behavioral intervention at age 2, would we still see these brain differences?”

Since the children needed to remain still enough to get their brain scanned, the researchers acknowledge that children with very severe hyperactivity may have been necessarily excluded. But the efforts the children (and their parents) made to remain still and further the research should not be undervalued, said James Griffin, the deputy chief of the child development and behavior branch of the National Institutes of Health, which partially funded the research.

“These children and their families are providing invaluable data that allow us to learn more about children with ADHD symptomology and atypical development as well as typical development,” he told the Times. “This is not an insignificant undertaking and commitment on their part.”

1 Jacobson, Lisa A., et al. “Anomalous Brain Development Is Evident in Preschoolers With Attention-Deficit/Hyperactivity Disorder.” Journal of the International Neuropsychological Society, 26 Mar. 2018, pp. 1–9., doi:10.1017/s1355617718000103.