Investigating the impact of the coronavirus pandemic on internalizing and functional symptoms and disorders in the Lifelines Biobank

The recent outbreak of the SARS-CoV-2 virus and the subsequent coronavirus disease 2019 (COVID-19) pandemic has the world currently in its grip. To contain the spread of the virus and reduce the risk of infection, the Dutch government, similarly to others across the world, has gradually imposed policies and protection measures, such as school closures, stay-at-home requests, and guidelines for adjusted social behavior during the pandemic. Our understanding of the physiological and psychological impact of the pandemic and the subsequent changes to our society on individuals and their health and well-being is currently still in its infancy. Given the ever-developing situation of the COVID-19 pandemic, it is important to establish research efforts to study how individuals and societies are impacted and to characterize possible vulnerable groups at risk for mental health problems, both in the short-term and in the long-term. 
Studies investigating the impact of previous city- and nationwide quarantines have reported negative psychological effects (PMID: 32112714). More studies are required because although previous studies can be informative for the current pandemic, they will not capture factors unique to COVID-19. Furthermore, small sample sizes, cross-sectional designs, a lack of population-based studies, and the use of non-validated or less reliable instruments to assess psychological symptoms are making it difficult to interpret previous studies' findings thereby limiting extrapolations to the current situation. Early reports of the impact of the current pandemic are reporting mixed findings with some studies reporting stable or even slightly decreased global mental health burden (Fried et al., PsyArXiv 2020), while others report increased levels of worry and stress (Fetzer et al., PsychArXiv 2020). There is therefore a need for longitudinal studies that allow for investigating both short- and long-term effects on those directly and indirectly impacted by COVID-19 pandemic. 
In the Lifelines Biobank, we have previously assessed symptoms of internalizing disorders (e.g. major depression (MD), generalized anxiety disorder (GAD)) using validated instruments (i.e. MINI questionnaire) designed to extract diagnoses according to international criteria (Diagnostic and Statistical Manual of Mental Disorders (DSM-IV)). We also assessed functional symptoms using the somatization subscale of the SCL-90, which measures somatic symptoms that are typically medically unexplained, and often cluster into so-called functional disorders (FD). This has three important implications: 1) we have detailed expertise on how to assess and analyze these symptoms in Lifelines, 2) we have incorporated the assessment of these symptoms in the weekly questionnaire of the Lifelines Corona Research Project, and 3) we have previous information on symptom expression, which provides a baseline to compare COVID-19-related symptoms with. The longitudinal design of the Lifelines Corona Research project enables high-resolution temporal tracking of internalizing disorder and functional symptoms and disorders in a population-based sample. As these symptoms and disorders often co-occur, investigating them jointly will help dissect both unique and shared effects of the COVID-19 pandemic on mental and functional symptoms and disorders. 
Here, we will assess the prevalence, incidence, and recurrence of internalizing and functional symptoms and disorders. Using previously collected information in Lifelines (pre-pandemic), we will determine if and how these symptoms and disorders are affected by the pandemic, both through direct and indirect effects in the short- and long-term. We will conduct specific analyses on how relevant mediators and moderators, such as the impact of news and media, sex, and genetic susceptibility to internalizing disorders affect the expression of symptoms and disorders. Our overall aim is to paint a detailed picture of the impact of the coronavirus pandemic on the Lifelines Biobank cohort.