Steven R. Pliszka

Up to 10% of school-age children have attention-deficit hyperactivity disorder (ADHD), which often persists into adulthood. ADHD can be associated with significant comorbidity of disruptive, mood, and anxiety disorders. Although many children with ADHD have good long-term outcomes, a significant subset has substance abuse, antisocial behavior, and mood disorders as adults. Pharmacotherapy with stimulants, atomoxetine, and alpha-agonists is highly effective in the short term; behavior therapy is valuable as an adjunct to medication or to address comorbid conditions. Multiple genes each likely contribute small effects to the risk of ADHD. Neuroimaging studies suggest that individuals with ADHD have insufficient activation of cortical attention networks, reduced activity of ventral striatal reward systems, and dysregulated control of the default mode network. No neuroimaging technique is yet useful clinically. More long-term studies of both medication and psychosocial interventions are needed to improve outcomes.

Background: There is increasing evidence that bipolar disorder (BD) and conduct disorder (CD) are co-occurring disorders. Magnetic resonance imaging has revealed differences in the structure and function of the frontal cortex in these disorders when studied separately; however, the impact of BD comorbidity on brain structure in adolescents with CD has not yet been examined. Method: We conducted an optimized voxel based morphometry (VBM) study of juvenile offenders with the following diagnoses: conduct disorder with comorbid bipolar disorder (CD-BD; n = 24), conduct disorder without bipolar disorder (CD; n = 24) and healthy controls (HC, n = 24). Participants were 13–17 years of age, in a residential treatment facility for repeat offenders. The three groups in this study were similar in age, gender, socioeconomic status and ethnicity. Results: We found CD-BD subjects had decreased volume relative to controls at the voxel level in the right medial prefrontal cortex (PFC). Using a Threshold-Free Cluster Enhancement (TFCE) technique, the CD-BD subjects had significantly decreased volumes of the right medial prefrontal cortex and portions of the superior and inferior frontal gyrus, anterior cingulate and temporal gyrus. The CD subjects did not have differences in brain volume compared to control subjects or CD-BD subjects. Conclusions: Our findings suggest the comorbidity between CD and BD is associated with neurobiological impact namely volumetric differences from healthy controls. Furthermore subjects with this comorbidity had poorer lifetime functioning, more mood and attentional dysfunction, and more medication exposure than subjects with CD who were not BD.

Neuroimaging in Developmental Clinical Neuroscience - February 2009