LAUSR

OBJECTIVE Several studies have found associations between a diagnosis or symptoms of major depressive disorder and markers of cellular aging and dysfunction. These investigations, however, are predominantly cross-sectional and focus on adults. In the present study, we used a prospective longitudinal design to test the cross-sectional association between depressive symptoms in adolescents and telomere length (TL) as well as mitochondrial DNA copy number (mtDNA-cn). METHOD 121 adolescents (Mean age=11.38, SD=1.03; 39 percent male) were followed for approximately two years. At baseline and follow-up, participants provided saliva for DNA extraction, from which measures of TL and mtDNA-cn were obtained. Depressive symptoms were obtained via the Children's Depression Inventory. RESULTS There was no association between depressive symptoms and markers of cellular aging at baseline; however, depressive symptoms at baseline predicted higher rates of telomere erosion (β=-.201, p=.016) and greater increases in mtDNA-cn (β=.190, p=.012) over the follow-up period. Markers of cellular aging at baseline did not predict subsequent changes in depressive symptoms. Furthermore, including number of stressful life events did not alter these patterns of findings. CONCLUSION These results indicate that depressive symptoms precede changes in cellular aging and dysfunction, rather than the reverse.