Ishiwata S, et al. - The researchers investigated whether cerebrospinal fluid (CSF) or plasma D-serine concentrations were altered in major depression disorders (MDD) and whether D-serine concentrations correlated with disease severity. They found some limitations in this study; sample size was relatively small and most patients were medicated. They demonstrated that CSF D-serine concentrations were associated with depression severity and HVA concentrations. To reveal the effect of medication and disease heterogeneity, additional research was required.

• The researchers enrolled 26 MDD patients and 27 healthy controls matched for age, sex, and ethnicity.
• Amino acids were measured in these samples using high-performance liquid chromatography with fluorometric detection.

• In patients with MDD, D-serine, and L-serine, the precursor of D-serine, levels in CSF or plasma were not significantly different compared to controls.
• Moreover, the researchers observed a significant correlation between D-serine levels in CSF and Hamilton Depression Rating Scale (HAMD)-17 score (r=-0.65, p=0.006).
• In MDD patients, a positive correlation was also found between CSF D-serine and HVA concentrations (r=0.54, p=0.007).
• In MDD, CSF D-serine concentrations were correlated with those of plasma (r=0.61, p=0.01) but not in controls.
• They also confirmed a significant correlation between D-serine and L-serine levels in MDD (r=0.72, p<0.0001) and controls (r=0.70, p<0.0001) in CSF.