Alterations of cellular aging markers in obsessive–compulsive disorder: mitochondrial DNA copy number and telomere length

BACKGROUND: The present study examined whether mitochondrial DNA copy number (mtDNAcn) and telomere length — key markers of cellular aging — were altered in male and female participants with obsessive–compulsive disorder (OCD) compared to healthy controls. We also tested for associations between these alterations and OCD-related clinical features and inflammatory index. METHODS: A total of 235 patients with OCD (38.7% female) and 234 healthy controls (41.5% female) were included. We quantified whole-blood mtDNAcn and leukocyte telomere length using quantitative polymerase chain reaction. We also calculated the neutrophil-to-lymphocyte ratio from complete blood cell counts. RESULTS: Multivariate analysis of covariance showed that OCD status had a significant overall effect on cellular aging markers in men (Wilks λ = 0.889, F(2,275) = 17.13, p < 0.001) and women (Wilks λ = 0.742, F(2,182) = 31.61, p < 0.001) after controlling for age, body mass index and childhood trauma. In post-hoc comparisons, men with OCD had lower mtDNAcn than controls (p < 0.001), but we found no between-group difference for telomere length (p = 0.55). Women with OCD had a significantly lower mtDNAcn (p < 0.001) and shortened telomere length (p = 0.023) compared to controls. Moreover, the lower mtDNAcn shown in the OCD group was significantly correlated with an increase in systemic inflammation for both sexes, as measured by neutrophil-to-lymphocyte ratio. LIMITATIONS: The present cross-sectional design did not allow us to infer a causal relationship between OCD disease status and cellular aging markers. CONCLUSION: The present study is, to our knowledge, the first to demonstrate alterations in mtDNAcn and telomere shortening in OCD. These results suggest that aging-associated molecular mechanisms may be important in the pathophysiology of OCD.