OBJECTIVE: Few magnetic resonance imaging (MRI) studies of bipolar disorder (BPD) have investigated the entire cerebral cortex. Cortical gray matter (GM) volume deficits have been reported in some studies of adults with BPD; this study assessed the presence of such deficits in children with BPD. METHODS: Thirty-two youths with DSM-IV BPD (mean age 11.2 +/- 2.8 years) and 15 healthy controls (HC) (11.2 +/- 3.0 years) had structured and clinical interviews, neurological examinations, neurocognitive testing, and MRI scanning on a 1.5 T GE Scanner. Image parcellation divided the neocortex into 48 gyral-based units per hemisphere, and these units were combined into frontal (FL), temporal (TL), parietal (PL), and occipital (OL) lobe volumes. Volumetric differences were examined using univariate linear regression models with alpha = 0.05. RESULTS: Relative to controls, the BPD youth had significantly smaller bilateral PL, and left TL. Analysis of PL and TL gyri showed significantly smaller volume in bilateral postcentral gyrus, and in left superior temporal and fusiform gyri, while the parahippocampal gyri were bilaterally increased in the BPD group. Although the FL overall did not differ between groups, an exploratory analysis showed that the right middle frontal gyrus was also significantly smaller in the BPD group. CONCLUSIONS: Children with BPD showed deficits in PL and TL cortical GM. Further analyses of the PL and TL found differences in areas involved in attentional control, facial recognition, and verbal and declarative memory. These cortical deficits may reflect early age of illness onset.

BACKGROUND: Youths with bipolar disorder are ideal for studying illness pathophysiology given their early presentation, lack of extended treatment, and high genetic loading. Adult bipolar disorder MRI studies have focused increasingly on limbic structures and the thalamus because of their role in mood and cognition. On the basis of adult studies, the authors hypothesized a priori that youths with bipolar disorder would have amygdalar, hippocampal, and thalamic volume abnormalities. METHOD: Forty-three youths 6-16 years of age with DSM-IV bipolar disorder (23 male, 20 female) and 20 healthy comparison subjects (12 male, eight female) similar in age and sex underwent structured and clinical interviews, neurological examination, and cognitive testing. Differences in limbic and thalamic brain volumes, on the logarithmic scale, were tested using a two-way (diagnosis and sex) univariate analysis of variance, with total cerebral volume and age controlled. RESULTS: The subjects with bipolar disorder had smaller hippocampal volumes. Further analysis revealed that this effect was driven predominantly by the female bipolar disorder subjects. In addition, both male and female youths with bipolar disorder had significantly smaller cerebral volumes. No significant hemispheric effects were seen. CONCLUSIONS: These findings support the hypothesis that the limbic system, in particular the hippocampus, may be involved in the pathophysiology of pediatric bipolar disorder. While this report may represent the largest MRI study of pediatric bipolar disorder to date, more work is needed to confirm these findings and to determine if they are unique to pediatric bipolar disorder.

BACKGROUND: The anterior cingulate cognitive division (ACcd) plays a central role in attentional processing by: 1) modulating stimulus selection (i.e., focusing attention) and/or 2) mediating response selection. We hypothesized that ACcd dysfunction might therefore contribute to producing core features of attention-deficit/hyperactivity disorder (ADHD), namely inattention and impulsivity. ADHD subjects have indeed shown performance deficits on the Color Stroop, an attentional/cognitive interference task known to recruit the ACcd. Recently, the Counting Stroop, a Stroop-variant specialized for functional magnetic resonance imaging (fMRI), produced ACcd activation in healthy adults. In the present fMRI study, the Counting Stroop was used to examine the functional integrity of the ACcd in ADHD. METHODS: Sixteen unmedicated adults from two groups (8 with ADHD and 8 matched control subjects) performed the Counting Stroop during fMRI. RESULTS: While both groups showed an interference effect, the ADHD group, in contrast to control subjects, failed to activate the ACcd during the Counting Stroop. Direct comparisons showed ACcd activity was significantly higher in the control group. ADHD subjects did activate a frontostriatal-insular network, indicating ACcd hypoactivity was not caused by globally poor neuronal responsiveness. CONCLUSIONS: The data support a hypothesized dysfunction of the ACcd in ADHD.