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A new study in the Archives of General Psychiatry reports that using functional magnetic resonance imaging in bipolar disorder has shown a trait abnormality in left ventral prefrontal cortex. In general, abnormalities in prefrontal and anterior cingulate cortices have been implicated in disturbances of attention, cognition, and impulse regulation and these have been found in bipolar disorder - particularly in the acute episodes.
Researchers studied bipolar I individuals (11 with elevated, 10 with depressed, and 15 with euthymic mood states) and 20 healthy control subjects matched for handedness and sex.
Results showed that "signal changes associated with specific mood states in bipolar disorder were detected in ventral prefrontal cortex, with a blunted increase in signal on the right side in the elevated mood group (P = .005) and an exaggerated increase in signal on the left side in the depressed group (P = .02) compared with the euthymic group. Patients (vs healthy controls) demonstrated blunted activation in a spatially distinct, rostral region of left ventral prefrontal cortex that was independent of mood state (P<.005)."
This study should be seen in the context that it is intended and that the findings and interpretations should be considered in light of the limitations of this study. The finding of right hemisphere lateralization of signal abnormalities associated with elevated mood states, in contrast to the left hemisphere lateralization of signal abnormalities associated with depression, is consistent with and elaborates upon findings from previous studies (such as Sakheim). The authors point out that "the specificity of our findings to the diagnosis of BD is unclear" and they raise a number of points describing the limitations.
Arch Gen Psychiatry. 2003;60:601-609
11:31:38 PM 
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