Frontal lobe bioenergetic metabolism in depressed adolescents with bipolar disorder: a phosphorus-31 magnetic resonance spectroscopy study

Shi X-F, Kondo DG, Sung Y-H, Hellem TL, Fiedler KK, Jeong E-K, Huber RS, Renshaw PF. Frontal lobe bioenergetic metabolism in depressed adolescents with bipolar disorder: a phosphorus-31 magnetic resonance spectroscopy study. Bipolar Disord 2012: 14: 607617. (c) 2012 The Authors. Journal compilation (c) 2012 John Wiley & Sons A/S. Objectives: To compare the concentrations of high-energy phosphorus metabolites associated with mitochondrial function in the frontal lobe of depressed adolescents with bipolar disorder (BD) and healthy controls (HC). Methods: We used in vivo phosphorus-31 magnetic resonance spectroscopy (31P-MRS) at 3 Tesla to measure phosphocreatine (PCr), beta-nucleoside triphosphate (beta-NTP), inorganic phosphate (Pi), and other neurometabolites in the frontal lobe of eight unmedicated and six medicated adolescents with bipolar depression and 24 adolescent HCs. Results: Analysis of covariance, including age as a covariate, revealed differences in PCr (p = 0.037), Pi (p = 0.017), and PCr/Pi (p = 0.002) between participant groups. Percentage neurochemical differences were calculated with respect to mean metabolite concentrations in the HC group. Post-hoc TukeyKramer analysis showed that unmedicated BD participants had decreased Pi compared with both HC (17%; p = 0.038) and medicated BD (24%; p = 0.022). The unmedicated BD group had increased PCr compared with medicated BD (11%; p = 0.032). The PCr/Pi ratio was increased in unmedicated BD compared with HC (24%; p = 0.013) and with medicated BD (39%; p = 0.002). No differences in beta-NTP or pH were observed. Conclusions: Our results support the view that frontal lobe mitochondrial function is altered in adolescent BD and may have implications for the use of Pi as a biomarker. These findings join volumetric studies of the amygdala, and proton MRS studies of n-acetyl aspartate in pointing to potential differences in neurobiology between pediatric and adult BD.