Serum molecules of the folate-driven one-carbon cycle as indicators of depressive tendencies in the elderly.

Aims: The folate-driven one-carbon (1C) cycle plays a significant role in the occurrence and development of depression. This study aimed to examine the potential of important molecules of the folate-driven 1C cycle as biomarkers for depressive tendency.

Methods: Ninety-five serum samples from older adults (age >60 years) were collected for this study. We quantified the concentrations of key metabolites and coenzymes of the folate-driven 1C cycle using Ultra-Performance Liquid Chromatography coupled with Tandem Mass Spectrometry (UPLC-MS/MS) and familiar clinical liver and kidney indicators in serum. Based on the differences in Hamilton Depression Rating Scale (HAMD)-17 scores, we compared the concentrations of measured molecules between elderly individuals with low and high levels of depression defined as HAMD-17 scores of 0-7 and 8-24, respectively. We also analyzed the concentration ranges of these molecules reflecting the level of depressive tendencies in the cohort.

Results: Our results showed significant variations in serum folate concentrations, SAM (S-adenosylmethionine), TBA (total bile acid), and SAM/SAH (S-enosylhomocysteine) ratios in elderly individuals with different HAMD-17 scores. Serum folate concentrations below 15.5 nmol/L and SAM/SAH ratios below 13.0 exhibited elevated levels of depressive tendency experienced among the participants.

Conclusions: The concentrations of serum folate, SAM, TBA, and SAM/SAH ratios might be used as indicators of depressive tendencies in the elderly population. A serum folate concentration of 15.5 nmol/L and a SAM/SAH ratio of 13.0 might be critical thresholds for indicating depressive tendencies in the Chinese elderly population.