640. BIOLOGICAL AGING INDICATORS IN STRESS-RELATED DISORDERS: A (NEURO)BIOLOGICAL PERSPECTIVE ON LIFESTYLE INTERVENTIONS IN PSYCHIATRIC PRACTICE

Abstract Background Large-scale studies link biological aging indicators with poorer mental health and unfavorable lifestyle factors, but its practical utility in clinical settings remains uncertain. A key open question is whether biological aging indicators are stable or dynamic in response to treatment. This study evaluates telomere length (TL), telomerase activity (TA), and the brain age gap (BAG) in individuals with depression and/or anxiety disorders following psychiatric treatment consisting of antidepressant use and running therapy. Aims & Objectives - To examine whether biological aging indicators are "accelerated" in individuals with stress-related disorders compared to healthy controls at baseline; - To examine whether biological aging indicators at baseline can predict treatment response; - To determine whether recovery from psychiatric symptoms following treatment is accompanied by a corresponding beneficial change of biological aging indicators. Method In a partially randomized patient preference design, individuals (18-70 years) with depression and/or anxiety disorders (N=139) were randomized or offered their preferred treatment—either antidepressants or group-based running therapy ≥2 weekly for 16 weeks. Blood samples and sMRI scans were taken at baseline and post-treatment. Sociodemographic, mental health (diagnosis and symptom severity) and biological aging indicators (TL, TA, BAG) were examined at baseline, and 16-week post-treatment for patients and at baseline for controls. Results First, we found that, at baseline, patients had shorter telomeres (p = .022, Cohen’s d = -0.35) and lower TA (p = .008, d = -0.35) compared to healthy controls. Second, baseline BAG showed a marginal association with treatment response (β = -0.61 years, p = 0.09), with responders (≥50% symptom reduction) exhibiting a higher BAG than non-responders, independent of treatment type. No significant BAG × treatment group interactions were observed for treatment response. Third, longitudinal analyses revealed that depressive and anxiety symptom severity was negatively associated with TL but not with TA. Additionally, no significant treatment group × time interactions were found, indicating that TL and TA trajectories over time did not differ between the antidepressant and running therapy groups. Discussion & Conclusions Our findings confirm (longitudinal) associations between stress-related disorders and telomere length and also reveal a case-control difference in telomerase activity at baseline. Preliminary evidence suggests that the brain age gap may serve as a clinically relevant predictor of treatment response. However, larger follow-up studies are needed to confirm these findings. Finally, no significant interactions with treatment group were observed, indicating that both antidepressants and running therapy had comparable effects.