Adversity, particularly in early life, can be associated with later illness. Clues to the responsible mechanisms may lie with the discovery of molecular signatures of stress, some of which include alterations to an individual’s somatic genome. Here, Cai and colleagues examined genome sequences from 11,670 women, and observed a highly significant association between major depression, the amount of mtDNA and telomere length. While both telomere length and mtDNA amount were associated with adverse life events, conditional regression analyses showed the molecular changes were contingent on the depressed state. The authors tested this hypothesis with experiments in mice, demonstrating that stress causes both molecular changes, which are partly reversible and can be elicited by the administration of corticosterone. They concluded that changes in the amount of mtDNA and telomere length are consequences of stress and entering a depressed state. Increased amounts of mtDNA may be a molecular marker of major depression and have important implications for understanding how stress causes the disease.
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Cai N, Chang S, Li Y, Li Q, Hu J, Liang J, Song L, Kretzschmar W, Gan X, Nicod J, Rivera M, Deng H, Du B, Li K, Sang W et al.: Molecular signatures of major depression. Curr. Biol. 25(9): 1146-1156 (2015).
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http://www.ncbi.nlm.nih.gov/pubmed/25913401