Dynamics of psychological distress: understanding the impact of intraindividual and interindividual factors in the Belgian population during the COVID-19 pandemic—A multilevel prospective cohort study

Camille Duveau^1,2*Pablo Nicaise¹Pierre Smith^1,2Katharina Seeber³Richard Bryant⁴Giovanni Corrao⁵Mireia Félez-Nóbrega^6,7Josep Maria Haro^6,7Irwin Hecker⁸Kerry Rodríguez McGreevy^7,9Roberto Mediavilla^10,11,7,9Maria Melchior⁸Ellenor Mittendorfer-Rutz¹²Matteo Monzio Compagnoni⁵Papoula Petri-Romão¹¹Antje Riepenhausen^13,14Jutta Stoffers-Winterling¹¹Anke Witteveen¹⁵Marit Sijbrandij¹⁵Vincent Lorant³

• ¹Université Catholique de Louvain, Louvain-la-Neuve, Belgium
• ²Sciensano, Brussels, Belgium
• ³Universite catholique de Louvain, Louvain-la-Neuve, Belgium
• ⁴University of New South Wales, Sydney, Australia
• ⁵Universita degli Studi di Milano-Bicocca, Milan, Italy
• ⁶Parc Sanitari Sant Joan de Deu, Sant Boi de Llobregat, Spain
• ⁷Centro de Investigacion Biomedica en Red de Salud Mental, Madrid, Spain
• ⁸INSERM, Paris, France
• ⁹Universidad Autonoma de Madrid, Madrid, Spain
• ¹⁰Instituto de Investigacion Hospital Universitario La Paz, Madrid, Spain
• ¹¹Leibniz-Institut fur Resilienzforschung (LIR) gGmbH, Mainz, Germany
• ¹²Karolinska Institutet Forsakringsmedicin, Stockholm, Sweden
• ¹³Charite - Universitatsmedizin Berlin, Berlin, Germany
• ¹⁴Humboldt-Universitat zu Berlin, Berlin, Germany
• ¹⁵Vrije Universiteit Amsterdam, Amsterdam, Netherlands

Longitudinal studies have identified an increase in psychological distress throughout the general population during the COVID-19 pandemic. Nevertheless, the determinants of the variation in psychological distress are unclear. This paper investigated factors that were likely to be associated with psychological distress variation: exposure to COVID-19 and psychosocial factors. Five waves of a prospective cohort survey were conducted with a convenience sample of the general population in Belgium between March 2020 and November 2021 (n=4,550). Psychological distress was measured using the GHQ-12. Two groups of exposures were investigated: self-reported exposure to COVID-19 and psychosocial factors (loneliness, social support, and social activities). We first partitioned the variance into an interindividual component (time-invariant) and an intraindividual component (time-variant). Linear mixed models were used for analysis. Most of the variance in psychological distress was interindividual. For both sources of variance (interindividual and intraindividual), the change in psychological distress was mainly associated with psychosocial factors, rather than pandemic-related factors. Loneliness emerged as the factor most strongly associated both with interindividual and intraindividual differences in psychological distress. Overall, these findings suggest that the variation in psychological distress between the waves was mostly influenced by social support, loneliness, and social activities, rather than by exposure to COVID-19. Mitigation policies aimed at controlling the pandemic should focus more on addressing specific individual psychosocial vulnerabilities.