Asymmetry of the prefrontal lobe in patients with attention
deficit hyperactivity disorder: A three-dimensional volumetric magnetic
resonance imaging study
Affiliations: Department of Pediatrics, Faculty of Medicine,
University of Yamanashi, Yamanashi, Japan | Interdisciplinary Graduate School of Medicine and
Engineering, University of Yamanashi, Yamanashi, Japan
Note: [] Correspondence: Dr. Hideaki Kanemura, Department of Pediatrics,
Faculty of Medicine, University of Yamanashi, 1110 Chuo, Yamanashi 409-3898,
Japan. Tel.: +81 55 273 9606; Fax: +81 55 273 6745; E-mail:
ykimu@yamanashi.ac.jp
Abstract: Asymmetries have been reported in several regions of the brain of
patients with developmental disorders such as autism, developmental language
disorder, and attention deficit hyperactivity disorder (ADHD). This study
focused on age-related anatomical asymmetries of the prefrontal lobe, which can
be manifestations of regional specialization of systems organization where
there are functional differences between the left and right hemispheres, in
children with ADHD. Subjects were 7 right-handed boys with ADHD aged 6–12
years and 5 age-matched controls. Exclusion criteria were full-scale
intelligence quotient less than 80, comorbid learning disorder or developmental
delay, evidence of medical or neurological disease on examination or by
history, or Tourette's syndrome. No subjects met criteria for conduct disorder
or oppositional disorder. Volume of the frontal and prefrontal lobes was
determined using a workstation and the prefrontal-to-frontal lobe and
left-to-right volume ratios were calculated. Both control and ADHD groups had a
larger aggregate volume of left frontal and prefrontal lobes than of right
frontal and prefrontal lobes. The leftward bias of the frontal lobe was
significantly pronounced in ADHD subjects than in control subjects (P=0.026).
In addition, the leftward bias of the prefrontal lobe was more pronounced in
ADHD subjects than in control subjects (P=0.0041). The left-to-right volume
ratio of the prefrontal lobe increased with age in both groups. The
left-to-right volume ratio of the frontal lobe was more pronounced in ADHD
(r=0.922, P=0.0014) than control group (r=0.521, P=0.414). In addition, the
left-to-right volume ratio of the prefrontal lobe was more pronounced in ADHD
(r=0.903, P = 0.0029) than control group (r=0.701, P=0.219). These findings
support the argument that right-sided prefrontal structural anomalies may occur
disproportionately in ADHD.
