Metabolomic predictors for late-life depression

Considering that metabolomics present an innovative path to determine novel biomarkers of late-life depression (LLD) outcomes and there are several known biological pathways involving tryptophan and lipid-inflammatory molecules (eicosanoids) which are relevant to depression, researchers sought to determine metabolomic predictors of long-term trajectories of LLD via performing systematic investigations. They assessed a convenience sample of ∼7000 Nurses’ Health Study (NHS) participants with known metabolites and who reported on depression items every 4 years from 1992-2016. Blood samples were obtained and stored under standard conditions between 1989 and 1990. Female nurses were of a mean age of 57.0 years when blood was drawn. Data on tryptophan metabolites were available for ∼6300 NHS participants and data on eicosanoids were available for ∼1300 NHS participants. Assessment yielded stronger signals for cross-sectional correlations of higher circulating levels of tryptophan, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) with lower risk of moderate or severe depressive symptoms. Four depressive symptom trajectory groups were identified: minimal depressive symptoms (63%), worsening depressive symptoms (12%), improving depressive symptoms (20%), and persistent severe depressive symptoms (5%). Overall findings revealed significant correlation of tryptophan and omega-3 fatty acid metabolites with LLD outcomes suggesting a possible role of these metabolites in the pathophysiology of LLD.