Oxidative DNA damage is increased in older adults with a major depressive episode: A preliminary study

Background: DNA oxidative damage is a marker of increased oxidative stress activity. Elevated DNA oxidative damage has been associated with major depressive disorder in young adults, but there is no information about DNA oxidative damage in late-life depression. This study aims to evaluate whether older adults with late-life depression (LLD) has increased DNA oxidative damage compared to healthy older adults. Methods: We included 92 participants (57 with LLD [73.2 ± 7.7 years-old] and 35 non-depressed subjects (Controls) [70.5 ± 7.4 years-old]). We analyzed the plasma 8‑hydroxy-2′-deoxyguanosine (8-oxo-dG), a marker of DNA oxidation, using a commercially-available ELISA assay. Results: LLD participants had significantly higher 8-oxo-DG levels compared to controls (P<0.001). 8-oxo-dG levels were significantly correlated with depressive symptoms as assessed by the Hamilton Depression Rating Scale (rho=0.34, p<0.001). The plasma levels of 8-OHdG were not significantly correlated with other clinical, neurocognitive, and demographic variables. Limitations: Our current results are limited by the relatively small sample size, cross-sectional design, and the recruitment of participants in tertiary center for assessment and treatment of LLD. Conclusions: Older adults with LLD have increased DNA oxidative damage. Our findings provide additional evidence for elevated oxidative stress activity in LLD and the possible activation of age-related biological pathways and enhanced biological aging changes in LLD.