Changes in the medial prefrontal cortex metabolites after 6 months of medication therapy for patients with bipolar disorder: A H-MRS study.

Aims: The study aimed to assess brain metabolite differences in the medial prefrontal cortex (mPFC) between acute and euthymic episodes of bipolar disorder (BD) with both mania and depression over a 6-month medication treatment period.

Methods: We utilized H-MRS technology to assess the metabolite levels in 53 individuals with BD (32 in depressive phase, 21 in manic phase) and 34 healthy controls (HCs) at baseline. After 6 months of medication treatment, 40 subjects underwent a follow-up scan in euthymic state. Metabolite levels, including N-acetyl aspartate (NAA), glutamate (Glu), and Glutamine (Gln), were measured in the mPFC.

Results: Patients experiencing depressive and manic episodes exhibited a notable reduction in NAA/Cr + PCr ratios at baseline compared to healthy controls (p = 0.004; p = 0.006) in baseline, compared with HCs. Over the 6-month follow-up period, the manic group displayed a significant decrease in Gln/Cr + PCr compared to the initial acute phase (p = 0.03). No significant alterations were found in depressed group between baseline and follow-up.

Conclusion: This study suggests that NAA/Cr + PCr ratios and Gln/Cr + PCr ratios in the mPFC may be associated with manic and depressive episodes, implicating that Gln and NAA might be useful biomarkers for distinguishing mood phases in BD and elucidating its mechanisms.