Lateralized abnormality of high energy phosphate metabolism in the frontal lobes of patients with bipolar disorder detected by phase-encoded 31P-MRS.

High energy phosphate metabolites were measured using phase-encoded in vivo phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in both the left and right frontal lobes of 25 patients with bipolar disorder. Eleven patients were examined in the depressive state, 12 in the manic state, and 21 in the euthymic state. Twenty-one age-matched normal volunteers were also examined. The phosphocreatine (PCr) peak area percentage in the left frontal lobe in the patients in the depressive state was decreased compared with that in the normal controls. It was significantly negatively correlated with the Hamilton Rating Scale for Depression score evaluated at the time of 31P-MRS examination. The PCr peak area percentage in the right frontal lobe in the patients in the manic and the euthymic states was decreased compared with that in the controls. These results are compatible with previous reports describing reduction of glucose metabolism in the left frontal lobe in depressive patients with bipolar disorder and trait-dependent right hemisphere dysfunction in bipolar disorder.