Brief reportMRI study of corpus callosum in children and adolescents with bipolar disorder
Introduction
The corpus callosum (CC) is the major inter-hemispheric commissure in the human brain. It integrates the activities of the left and right cerebral hemispheres and plays an important role in non-literal language, affective prosody, and functional connectivity in the motor and sensory cortices (Paul et al., 2003, Quigley et al., 2003). The genu and splenium of the CC connect prefrontal and temporo-parietal cortices (association areas), whereas the body and isthmus connect visual, auditory and somatosensory cortices (De Lacoste et al., 1985).
Anatomical or functional abnormalities in specific callosal regions (i.e., genu and splenium) that inter-connect important association areas could be relevant to the pathophysiology of bipolar disorder as well as the cognitive disturbances seen in these patients (Soares and Mann, 1997). Impairments in fine motor skills and cognitive disturbances often occur in bipolar patients (Wilder-Willis et al., 2001, Borkowska and Rybakowski, 2001), and the degree of impairment correlates with reduced areas of midsagittal brain structures in bipolar patients with psychotic features (Coffman et al., 1990).
We examined CC morphology in children and adolescents with bipolar disorder and healthy controls to determine whether any structural abnormalities were already present early in the illness course.
Section snippets
Methods
Sixteen children and adolescents with bipolar disorder (8 females and 8 males, mean age ± s.d = 15.5 ± 3.4 y, age range from 10 to 20 y) were recruited. All patients met DSM-IV diagnostic criteria for bipolar disorder, type I (n = 12), bipolar disorder, type II (n = 3), or bipolar disorder not otherwise specified (n = 1), according to the Structured Clinical Interview for DSM-IV (SCID) (Spitzer et al., 1994), for subjects 18 years old or older, or the Schedule for Affective Disorders and Schizophrenia for
Results
There were no significant differences in age, gender, ethnicity or hand preference between the bipolar patients and the healthy controls. Bipolar patients and healthy control subjects did not differ significantly on any measures of CC length or area (all P > 0.05). Splenium circularity was significantly lower in bipolar patients than healthy controls [bipolar splenium circularity = 0.72 ± 0.06, control splenium circularity = 0.77 ± 0.05, F(1,32) = 8.35, P = 0.007].
Partial correlation analysis, controlled for
Discussion
We found no evidence of abnormalities in CC area and length in juvenile bipolar patients. Adult bipolar patients are reported to have smaller CC areas (Coffman et al., 1990, Brambilla et al., 2003) and lowered CC signal intensity (pointing to abnormal myelination) compared with healthy controls (Brambilla et al., 2004). We found a significant shape difference with a less circular splenium in the bipolar group compared with the healthy controls. Splenium circularity is a measure scaled in
Acknowledgments
This work was partly supported by grants MH 01736, MH 55123, MH 30915, and MH 59929 from the National Institute of Mental Health, RR020571 from the National Center for Research Resources, NARSAD, the Krus Endowed Chair in Psychiatry (The University of Texas Health Science Center at San Antonio) and the CAPES Foundation (Brazil).
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