Preschoolers aged 4 or 5, who have symptoms of attention deficit hyperactivity disorder or ADHD, show significant brain structural differences in imaging scans.

The brain scans from a study commissioned by the National Institutes of Health showed that signs of atypical neurological development are already prominent by the time a patient reaches the preschool stage.

ADHD is a mental health disorder characterized by impulsive behaviors, inability to focus, and hyperactivity.

James Griffin, deputy chief of the Child Development and Behavior Branch at Eunice Kennedy Shriver National Institute of Child Health and Human Development, said that the study intended to find the early signs of abnormal brain development.

"They were surprised at how early these differences were already evident in the brain," Griffin said.

The study, led by Dr. E. Mark Mahone, presented valuable insight in neurological science. Limited literature is available in citing brain differences among ADHD patients of various ages.

What ADHD Looks Like

A total of 90 children, 38 young preschoolers, and 52 older preschoolers who have shown signs of ADHD, were sent to the Kennedy Krieger Institute in Baltimore to participate in the study.

Imaging scans showed that children who exhibited ADHD symptoms have lesser matters in multiple areas of their brain. This finding is consistent with parental reports of children showing aggressive behavior.

The most significant changes were found in the temporal and prefrontal lobes, which control the physical activities, attention, and motor control.

Children who showed more impulsive behaviors have a hard time getting scanned. Scientists ruled that those who were scanned may have moderate symptoms.

"One of our big questions was thinking about an early-onset disorder and linking it to early-onset brain anomalies. [The results] tell us that this is not just a behavioral disorder. It is a neurological disorder," said Lisa Jacobson, one of the co-authors of the study.

Griffin said that these results allow them to better understand brain development among ADHD and potential ADHD patients. The group will conduct follow-up studies and will have regular brain scans until the subjects reach a certain age.

Future studies are warranted to further investigate how ADHD symptoms are related to differences in brain structure. More importantly, Griffin's team has laid the foundation of the study.

The Centers for Disease Control and Prevention reported that more than 6 million Americans aged 2 to 17 were diagnosed with ADHD. Some experts believe that many cases are overdiagnosed, saying that brain scans alone will not solve the problem.

The study was published on Monday in the Journal of the International Neuropsychological Society.

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