The purpose of this study was to investigate whether mitochondrial DNA (mtDNA) content of peripheral blood leukocyte is related to depression in community-dwelling old women. A total of 142 community-dwelling women, older than 60 years, were included in the study. The mtDNA copy number, which represents the mtDNA content, was measured using real-time PCR methods. Patients with depression defined as the subjects whose 15-question geriatric depression scale (GDS) score was ≥ 8 or who were taking anti-depressant medication. We also measured cognitive function, physical performances (gait speed, chair-stand times, tandem standing times) and metabolic parameters. The depression group had a significantly lower mtDNA copy number than the control group (71.5 vs. 107.3; interquartile range (IQR) = 42.7-116.0 vs. 51.7-202.1; p = 0.028). The Korean version of the mini mental state examination (K-MMSE) score and physical performance score were significantly lower in the depression group than in the control group (p = 0.041, and p = 0.002, respectively). After adjustment for confounding factors using multiple logistic regression analysis, mtDNA copy number was significantly related to depression (p = 0.025). We demonstrated that low leukocyte mtDNA content is related to depression in community dwelling old women. This finding suggests that mitochondrial dysfunction could be a mechanism of geriatric depression.
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