Major depressive disorder (MDD) is a severe psychiatric health condition. The illness is characterized by heterogenous symptoms like a depressed mood, a loss of pleasure and interest, and a reduction in energy which results in fatigue and lower activity. While the psychological and social risk factors for developing and maintaining a MDD are already largely known, the underlying biological mechanisms are not yet fully understood.
The interdisciplinary field of psychoneuroimmunology aims to address this problem. It deals with the interaction of the psyche, the nervous, endocrine, and the immune system. Accelerated cell aging in form of premature immune cell telomere length shortening has already been shown to be associated with depression. Furthermore, the upcoming approach of metabolomics is involved to uncover biological pathways in psychiatric disorders. In this study both approaches were combined by investigating the association between blood serum metabolites and telomere length (TL) in peripheral blood mononuclear cells and T cell subsets in 44 women with and without MDD. Correlation analyses showed that a total of n = 13 endogenous and exogenous metabolites were significantly associated with TL measured in one of the five different immune cell types. Additionally, the association between these metabolites and depressive symptoms were investigated in the total sample as well as in the MDD group separately. The current findings could provide a deeper understanding of the metabolic processes driving the relationship between depression and immune cell TL.