Association of mitochondrial DNA copy number with self-rated health status

PURPOSE: In aging adults, mitochondrial dysfunction may be an important contributor. We evaluated the association between mitochondrial DNA (mtDNA) copy number, which is a biomarker for mitochondrial function, and self-rated health status. PATIENTS AND METHODS: We conducted a cross-sectional study of patients enrolled within the Mayo Clinic Biobank. We utilized the questionnaire and sequence data from 944 patients. We examined the association between mtDNA copy number and self-rated health status with 3 collapsed categories for the latter variable (excellent/very good, good, and fair/poor). For analysis, we used proportional odds models after log-transforming mtDNA copy number, and we adjusted for age and sex. RESULTS: We found the median age at enrollment was 61 years (25th–75th percentile: 51–71), and 64% reported excellent or very good health, 31% reported good health, and 6% reported fair/poor health. Overall, the median mtDNA copy number was 88.9 (25th–75th percentile: 77.6–101.1). Higher mtDNA copy number was found for subjects reporting better self-rated health status after adjusting for age, sex, and comorbidity burden (OR =2.3 [95% CI: 1.2–4.5] for having better self-rated health for a one-unit increase in log-transformed mtDNA copy number). CONCLUSION: We found that a higher mtDNA copy number is associated with better self-rated health status after adjustment for age, sex, and comorbidity burden. The current study implies that mtDNA copy number may serve as a biomarker for self-reported health. Further studies, potentially including cohort studies, may be required.