A new study has found that children diagnosed with attention deficit hyperactivity disorder, or ADHD, have reduced volume in certain areas of the brain that impact behavioral control.

That’s according to the researchers who published a study last week in the Journal of the International Neuropsychological Society that examined the brain development of 90 children between the ages of 4 and 5.

The researchers from the Kennedy Krieger Institute in Baltimore used high-resolution MRI scans, as well as behavioral and cognitive measures, to examine the brain development of the children, including 52 who had ADHD symptoms but were not on medication.

They found that compared to children without symptoms, the children with ADHD symptoms showed a significant reduction in brain volume in multiple areas including the frontal, temporal, and parietal lobes.

In patients with ADHD symptoms, the regions of the brain that showed the greatest reductions were those that are critical for cognitive and behavioral control, as well as predictability of behavioral symptoms.

Although many studies have focused on ADHD in school children, the study was the first of its kind to focus on preschool-aged children and brain volume.

E. Mark Mahone, PhD, ABPP, lead study author and research scientist at the Kennedy Krieger Institute, explained that finding evidence of ADHD via an MRI scan can be helpful for children in order to establish a “biomarker” for the disease.

“It is very important to study behavior and brain development in preschool children with symptoms of ADHD because we usually start to see symptoms of the disorder in this age range, or earlier,” Mahone told Healthline. “The earlier we can identify ‘biomarkers’ of the condition, the better we will be at identifying earlier and more focused interventions that can help reduce the later risks seen in the disorder.”

The challenges of understanding and identifying ADHD

ADHD is a chronic neurodevelopmental disorder believed to affect 11 percent of school age children. The symptoms of the disorder also persist into adulthood in more than 75 percent of cases.

These symptoms include inappropriate levels of impulsivity, inattention, and hyperactivity.

It is the most commonly diagnosed form of mental disorder during preschool and early childhood years.

While Mahone notes that symptoms of ADHD can also appear in a “typical” child’s development, parents should take note if these symptoms are interfering with daily life or are excessive.

“What leads these symptoms to be considered ‘ADHD’ is how frequent, intense, and prolonged they are, and how much they interfere with the child’s functioning in life,” he said. “It is when symptoms are excessive for age, and interfere with major life activities on a regular basis that we consider it to be a ‘disorder’—in this case, ADHD.”

Getting an accurate diagnosis of ADHD can sometimes be challenging. Dustin Sarver, PhD, assistant professor of pediatrics at the University of Mississippi Medical Center, said this can be due to a lack of sufficient assessment to rule out other psychological or health conditions that can mimic ADHD.

“Since nearly all other mental health disorders have inattention or hyperactivity as a potential symptom or outcome, the challenge is making sure your provider has considered alternatives so that other diagnoses are not mistaken for ADHD,” he told Healthline.

Dr. James T. McCracken, professor of child psychiatry at the David Geffen School of Medicine at the University of California, Los Angeles, told Healthline it is currently difficult to diagnose ADHD in the very young.

“It is probably most difficult to make a diagnosis of ADHD in preschoolers,” McCracken said. “A lot of the behaviors that make up the core symptoms, the diagnostic features of the disorder, overlap quite a bit with the normal range of behavior.”

McCracken says it is important people understand that ADHD has been found on every continent in the world. This has led experts to believe the disorder is not caused by bad environments, or through exposure to social media or television.

“It really is a biomedical condition that at many times does require medical treatment. But fortunately, we can help the majority of children and adults with it be much more functional and help them reduce their challenges significantly,” he said.

The future of ADHD research

The researchers from the Kennedy Krieger Institute plan to follow the children from the study through their childhood years into adolescence to better understand the disorder.

“Our hope is that by following these children from early on in life, we will be able to determine which early brain and behavioral signs are most associated with later difficulties, or even better, which aspects of early development can predict better outcome and recovery from the condition," said Mahone.

ADHD can impact quality of life differently at different ages. Although many parents focus on the academic impacts of behavioral difficulties from ADHD, Sarver says there are a number of other important factors to consider that extend well beyond school years.

“ADHD can affect health risks such as accident injuries in young children, social and peer relationships as they get older, family and sibling relationships, risk-taking behaviors and the negative consequences that may be experienced, for example poor driving and accidents, sexual outcomes or early parenthood, and greater risk of substance abuse,” Sarver said. “In adults, ADHD can affect job performance, finance management, marital discord and risk of divorce.”

Although much is known about the functional consequences of ADHD, there is still more to learn about the biological factors that contribute to the disorder.

Mahone is hopeful the study will assist in reducing the negative impacts of ADHD.

“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,” he said.