Delia Ibáñez ^1,2 Elena Condominas ^3,4 Josep M. Haro ^3,4 Iago Giné-Vázquez ^3,4 RADAR-MDD-Spain** . ⁵ Raquel Bailón ^4,6 Esther García ^7,8 Spyridon Kontaxis ^4,6 Maria T. Peñarrubia-Maria ^10,9 Belen Arranz ^3,4 Raúl Llaosa-Scholten ¹¹ Lluisa Gardeñes ⁹ Matthew Hotopf ^3,4 Faith Matcham ^12,13 Femke Lamers ^14,15 Brenda W. Penninx ^14,15 Peter Annas ¹⁶ Amos Folarin ¹² Vaibhav Narayan ¹⁷ Rodrigo A. Lima*† ^3,4* Sara Siddi† ^3,4

• ¹ Department of Psychiatry and Clinical Psychology, Hospital Clínic de Barcelona, Barcelona, Spain
• ² Autonomous University of Barcelona, Barcelona, Catalonia, Spain
• ³ Research, Innovation and Teaching Unit, Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
• ⁴ Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain
• ⁵ RADAR-MDD-Spain, Barcelona, Spain
• ⁶ Aragón Institute of Engineering Research (I3A), Instituto de Investigación Sanitaria de Aragón (IIS Aragón), University of Zaragoza, Zaragoza, Spain
• ⁷ Centros de Investigación Biomédica en Red en el área de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
• ⁸ Microelectrónica y Sistemas Electrónicos, Universidad Autónoma de Barcelona, Bellaterra, Spain
• ⁹ Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP), Instituto de Salud Carlos III, Madrid, Spain
• ¹⁰ Unitat de Suport a la Recerca Regió Metropolitana Sud, Fundació Institut Universitari per a la Recerca a l’Atenció Primària de Salut Jordi Gol i Gurina (IDIAPJGol), Barcelona, Spain
• ¹¹ FEA Psicología Clínica, HU Institut Pere Mata, Vendrell, Spain
• ¹² Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
• ¹³ School of Psychology, University of Sussex, East Sussex, United Kingdom
• ¹⁴ Department of Psychiatry, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
• ¹⁵ Amsterdam Public Health, Mental Health Program, Amsterdam, Netherlands
• ¹⁶ H. Lundbeck A/S, Valby, Denmark
• ¹⁷ Research and Development Information Technology, Janssen Research & Development, LLC, Titusville, NJ, United States

Aim: To evaluate the longitudinal association of sedentary behaviour, light and moderate-to-vigorous physical activity (MVPA) participation with depressive symptoms and whether their possible association changed depending on the pandemic phase. Methods: This longitudinal study conducted secondary analysis from the Spanish cohort of the Remote Assessment of Disease and Relapse – Major Depressive Disorder (RADAR-MDD) study. Depressive symptoms were assessed by the Patient Health Questionnaire (PHQ-8). Sedentary behaviour and physical activity were estimated via wrist-worn devices. Linear mixed models evaluated the longitudinal associations of sedentary behaviour and physical activity (light and moderate-to-vigorous intensities) with depressive symptoms. Results: In total, 95 participants (67.5% women, 53.0 [±10.5] years of age on average) were monitored pre-Covid-19 and included in the analyses. Pre-Covid-19, 73.7% of participants presented depression, and, on average, participated in 13.2 (±1.08) hours/day of sedentary behaviour, 2.42 (±0.90) hours/day of light physical activity and 23.6 (±19.80) minutes/day of MVPA. Considering all the observations (from November 2019 to October 2020), an additional hour/day of sedentary behaviour was longitudinally associated with higher depressive symptoms (βstd=0.06, 95% confidence interval (CI) 0.10 to 0.47), whereas an additional hour/day in light physical activity was associated with lower depressive symptoms (βstd=-0.06, 95% CI -0.59 to -0.15). Time in MVPA was not associated with depressive symptomatology. The association of sedentary behaviour and light physical activity with depressive symptoms was significant only during pre-Covid-19 and Covid-19 relaxation periods, whereas during the strictest periods of the pandemic with regards to the restrictions (lockdown and de-escalation), the association was not observed. Conclusions: Sedentary behaviour and light physical activity were longitudinally associated with depressive symptoms in participants with a history of MDD. The incorporation of light physical activity should be stimulated in adults with a history of MDD. Neither sedentary behaviour nor light physical activity were associated with depressive symptoms during the most restrictive COVID-19 phases, whereas sedentary behaviour (positively) and light physical activity (negatively) were associated with depressive symptoms in persons with MDD before and after the COVID-19 pandemic.