Boys and girls with attention deficit hyperactivity disorder (ADHD) have differences in brain structure that coincide with the gender-specific nature of their clinical presentation, a new imaging study shows. Using magnetic resonance imaging (MRI) to compare the brain structure of boys and girls with ADHD to that of normally developing children, the researchers found that the area of the premotor cortex was reduced in boys with ADHD compared to normal children, while in girls of the same age group it was the area of the prefrontal cortex that was reduced, with the latter correlating more strongly with organizational skills. The findings suggest that boys, at least at this age, show more problems related to motor control, while girls show abnormalities at higher levels of organization and planning, according to Dr. Mostofsky and team from the Kennedy Krieger Institute in the U.S. The study was published in the recent issue of NeuroImage Clinical. Examining Brain Structure ADHD research focused on gender differences has focused primarily on functional comparisons, and there is a dearth of studies assessing structural differences in the brains of boys and girls with ADHD, with only one other study focusing on comparing differences in frontal lobe morphology. In this study, researchers imaged 226 children aged 8-12 years with brain scans using 3T magnetized rapid gradient echo (MP-RAGE) MRI. Included were 93 with ADHD, including 29 girls, and the remaining 133 were normally developing children, including 42 girls. Using newly developed automated frontal lobe mapping, the researchers found that total prefrontal cortex area was reduced overall in girls with ADHD compared to same-sex normal control individuals, while this change was not found in boys. The results showed that total premotor cortex area was reduced overall in boys with ADHD compared to same-sex normal control individuals, while this change was not found in girls. Whereas the reduction in premotor area in boys was predominantly found in bilateral premotor cortical areas, the reduction in prefrontal area in girls was predominantly found in bilateral supplementary motor complex areas. There were no significant differences in cortical thickness between the groups. The researchers hypothesized that the differences may simply represent different developmental stages in boys and girls of the same age. It is well known that girls mature earlier than boys, and this pattern also includes early maturation of brain structures and related functions, with motor functions maturing earlier than prefrontal structures, and with this in mind, then at an earlier age in girls we may see motor-related problems similar to those that boys show later. Follow-up longitudinal studies with follow-up need to be understood to explore whether the differences seen in this preadolescent time window are due to developmental lag. Differences may persist at different stages of development, however, even if limited, these differential differences in functioning between boys and girls with ADHD should be supported by substantial evidence. The researchers noted that clinically, boys are more often diagnosed as mixed and show symptoms of hyperactivity/impulsivity, whereas girls with ADHD tend to be diagnosed with an attention-deficit-dominant type. In this study, about 70 percent of ADHD patients were given excitatory medications while the study was underway, and while the researchers concluded that there was no significant effect of the medications on the surface area of the prefrontal cortex, the differences between the prefrontal cortex of the ADHD patients on medication and the normal control individuals were greater. Commenting on the trial, Dr. Galanter, from the Child and Adolescent Psychiatry Training Program at the State University of New York (SUNY), USA, said, “This study is very promising and underscores the importance of a better understanding of the differences in presentation that may be seen in boys and girls with ADHD. As prudent physicians, we should use data to influence decisions. Children with ADHD or suspected ADHD still need a careful and comprehensive clinical evaluation and a functional treatment program that can address different aspects, including those involving school, home, and peers.”