The role of hypothyroidism in the resilience against depressive episodes during covid pandemic in a cohort of old adults

Background: Hypothyroidism is associated with major depressive disorder and treatment-resistant depression. However, thyroid function tests at rest may not fully capture the thyroid's stress response, possibly explaining its role in depression vulnerability. This study aimed to assess whether Hypothyroidism affected resilience to depressive episodes in older adults during the COVID-19 lockdown. Methods: We analyzed a cohort from a randomized controlled trial on active aging conducted a year prior. Participants (aged 65+) were reassessed during the lockdown (March-April 2020). Depression was measured using the PHQ-9, quality of life with the SF-12, and social rhythms with the Brief Social Rhythms Scale. Comparisons between individuals with and without Hypothyroidism were made using Fisher's exact test and two-way ANOVA. Results: Of 93 participants, 15 had Hypothyroidism, predominantly female (80% vs. 48.7%, p=0.026). Pre-lockdown depressive episodes were similar between groups (20% vs. 16.67%, p=0.432). During lockdown, depressive episodes decreased in euthyroid participants but increased significantly in those with Hypothyroidism (7.69% vs. 33.3%, p=0.015). Quality of life worsened more in the hypothyroid group (time × group interaction, p=0.005). Social rhythm dysregulation decreased in both groups but remained higher in hypothyroid individuals. Conclusion: Older adults generally displayed resilience during the pandemic. However, those with Hypothyroidism experienced increased depressive episodes and worsened quality of life, suggesting reduced stress adaptability despite hormone replacement therapy. This consideration highlights the potential need for interventions addressing both biological and psychosocial factors in managing depression risk in hypothyroid individuals.