Changes in behavioural and psychological cardiovascular risk factors during the COVID-19 pandemic and patterning by SEP

The COVID-19 pandemic has led governments around the world to impose restrictions on outdoor and social activities in order to contain further spread of the SARS-CoV-2 virus, including home quarantine and mandatory legislation prohibiting gatherings of people. Although home quarantine has proven to be an effective tool to protect public health when facing an acute infectious disease threat, it is likely to have adverse effects on the population’s cardiovascular risk burden through affecting a range of cardiovascular risk factors, including lifestyle behaviours and psychological well-being (1). 
Naturally, home quarantine inhibits individual’s ability to move around freely, potentially compromising the amount of physical activity one can engage in. Recent work in Canada shows that among 1,098 survey respondents who were classified as ‘inactive’, 41% indicated to engage in less physical activity during COVID-19 pandemic as compared to 22% of respondents that were classified as ‘active’. However, increased levels of physical activity during COVID-19 were also reported by 33% and 40% of inactive and active respondents, respectively (2). A survey among 3,533 individuals in an Italian population generally showed no differences in physical activity before and after COVID-19, except from a slight increase in high training frequency (≥ 5 times/week) during COVID-19. 
Additionally, the pandemic may impact upon dietary behaviours through inducing more unhealthy stress-related eating or promoting purchases of packaged shelf food (3). As for changes in dietary behaviours during COVID-19, an Italian survey showed that 34% of the respondents indicated to have more appetite during home quarantine and 37% and 36% of the respondents indicated to eat more or less healthy food, respectively (4). 
Besides changes in behavioural risk-factors, home quarantine may also induce changes in psychological risk-factors. A recent rapid review of the evidence showed that quarantine may lead to post-traumatic stress symptoms, confusion, and anger (5). There is an increasing evidence base that shows that adverse mental health, including anxiety, depression and stress, have a negative impact on cardiovascular health both through biological changes but also through exacerbating engagement in unhealthy lifestyle behaviours (6). For example, research shows that stress impairs efforts to be physically active (7) and influences brain networks and hormones involved in different aspects of eating behaviour (8). 
Additionally, it is well known that cardiovascular risk-factors show strong patterning by socioeconomic position (SEP), with those with lower SEP having less favorable risk profiles (9). Simultaneously, recent work shows that people with a low SEP also experienced more adversities – e.g.  loss of income – during the lockdown (10), which potentially also worsens lifestyle behaviours and psychological well-being and thus cardiovascular risk. 
Taken together, the home quarantine necessitated by the COVID-19 pandemic may have profound consequences for the cardiovascular risk burden. Based on the previous evidence, we hypothesize that the COVID pandemic exacerbates unhealthy lifestyle behaviours in those who already engaged in more unhealthy lifestyle behaviour before the COVID pandemic. Second, we hypothesize that especially people with a low SEP may be vulnerable to experience worsening of behavioural and psychological cardiovascular risk-factors. However, evidence assessing changes in cardiovascular risk-factors during COVID-19 from large population-based cohorts is currently lacking. Therefore, we aim to study changes in behavioural and psychological cardiovascular risk factors during the COVID-19 pandemic and patterning by SEP using data from a large prospective observational cohort study.