Bipolar II depression with obsessive symptoms linked to lower vmPFC metabolite ratios

Adolescents with bipolar II disorder experiencing a depressive episode with clinically significant obsessive–compulsive symptoms had lower ratios of two ventromedial prefrontal cortex metabolites than comparison groups, according to a cross-sectional proton magnetic resonance spectroscopy study. Researchers compared 28 adolescents with bipolar II depression and clinically significant obsessive–compulsive symptoms, 30 adolescents with bipolar II depression without those symptoms, and 26 healthy controls. The N-acetylaspartate-to-creatine ratio, NAA/Cr, was lowest in the group with obsessive–compulsive symptoms, while the glutamate-plus-glutamine-to-creatine ratio, Glx/Cr, was significantly lower than in both other groups.

The investigators used single-voxel proton magnetic resonance spectroscopy to examine four metabolite ratios in the ventromedial prefrontal cortex: NAA/Cr, choline-containing compounds to creatine, or Cho/Cr; myo-inositol to creatine, or mI/Cr; and Glx/Cr. Both bipolar II depression groups had significantly lower NAA/Cr values than healthy controls. The group with clinically significant obsessive–compulsive symptoms also had significantly lower Glx/Cr than adolescents with bipolar II depression without those symptoms and healthy controls. These group differences remained significant after adjustment for illness duration and other covariates, according to the study’s abstract.

The clinical data also showed that adolescents with bipolar II depression and obsessive–compulsive symptoms had a longer illness duration than those in the bipolar II group without clinically significant symptoms. A different relationship emerged for depressive symptom scores. Glx/Cr was negatively correlated with scores on the 24-item Hamilton Depression Rating Scale only among adolescents with bipolar II depression who did not have clinically significant obsessive–compulsive symptoms. In other words, higher Glx/Cr values were associated with lower depression ratings within that particular group, rather than across all participants.

In an exploratory receiver operating characteristic analysis conducted within the available sample, NAA/Cr showed preliminary discrimination between adolescents with bipolar II depression and obsessive–compulsive symptoms and healthy controls. The area under the curve was 0.870 for that comparison and 0.733 when distinguishing the two bipolar II depression groups from one another. Because these were in-sample estimates, the analysis does not establish how accurately NAA/Cr would perform in new patients. The researchers stated that independent validation across the full range of obsessive–compulsive symptom severity is required.

The results support differences in vmPFC neurometabolite ratios among the groups studied, but they do not provide a validated clinical test or establish what caused the observed differences. Because the study was cross-sectional, it cannot determine whether lower NAA/Cr or Glx/Cr ratios preceded symptoms, developed alongside them or reflected other aspects of illness. The findings instead identify a pattern that requires independent replication and broader assessment before it can be applied as a biomarker.

Subject of Research: Ventromedial prefrontal neurometabolite ratios in adolescents with bipolar II depression and obsessive–compulsive symptoms

Article Title: Neurometabolic profiles of the ventromedial prefrontal cortex in adolescents with bipolar depression and clinically significant obsessive–compulsive symptoms: a cross-sectional proton magnetic resonance spectroscopy study

Article References: Li, Y., Wang, C., Shen, X., Hu, M., Tong, G., Zhang, C., Qu, Y., & Zou, S. (2026). Neurometabolic profiles of the ventromedial prefrontal cortex in adolescents with bipolar depression and clinically significant obsessive–compulsive symptoms: a cross-sectional proton magnetic resonance spectroscopy study. BMC Psychiatry. https://doi.org/10.1186/s12888-026-08762-y

Image Credits: AI Generated

DOI: 10.1186/s12888-026-08762-y

Keywords: bipolar II disorder, adolescent depression, obsessive–compulsive symptoms, ventromedial prefrontal cortex, proton magnetic resonance spectroscopy, NAA/Cr, Glx/Cr, neurometabolites, cross-sectional study, Neurometabolic, profiles, ventromedial