Stressors and protective factors of the COVID-19 pandemic in the mental health of the world population: an integrative review

This paper aimed to analyze the mental health protective factors and stressors of the pandemic in Brazil and internationally. We conducted an integrative literature review by searching for scientific publications indexed in the LILACS and MEDLINE databases from January to December 2020. Twenty-nine papers have been analyzed by author, year, country of study, methodology; mental health stressors and protective factors related. We concluded that people subjected to restrictive measures imposed by the COVID-19 pandemic are vulnerable to mental health problems. However, very few studies have evaluated the related psychosocial factors despite the global impact.


Introduction
On January 30, 2020, the World Health Organization (WHO) announced the outbreak of the new Coronavirus (2019-nCoV) as a Public Health Emergency of International Concern, in which all countries have implemented measures to control and combat the COVID-19 disease.Researchers and health professionals have played a challenging role in this pandemic since the disease does not have a wholly defined clinical risk, and the accuracy of the transmission, infection, lethality, and mortality patterns is unknown 2 .
Brazil recorded the second-highest number of accumulated cases (11,950,459)  globally in Epidemiological Week 11, on March 20, 2021.Considering the level of incidence, the country had a rate of 56,435.1 cases for every 1 million inhabitants, ranking 27 th among countries with the highest incidence (cases of COVID-19 per 1 million inhabitants).The mortality coefficient stood at 138.2 deaths per 100 thousand inhabitants, ranking 17 th in the world for mortality by COVID-19.However, we should emphasize that each country is in a specific pandemic stage, where some are experiencing a significant increase in cases, as in Brazil 3 .
In the COVID-19 Weekly Epidemiological Update published on March 28 by the WHO, the number of deaths worldwide increased for the second consecutive week, with a growth of 5% against the previous week.The most considerable number of new cases was from Brazil (5,533,024, growth of 5%), followed by the United States (421,936, growth of 13%), and India (372,494, growth of 55%) 4 .
Besides the physical symptoms caused by the infection, the virus circulation affects people's mental health, generating anxiety and depression 5 .The fear of the unknown, the spread of the disease, and the impact on the economy exacerbate the anxiety of individuals with pre-existing mental health conditions and healthy individuals alike, as people tend to feel anxious and insecure when the environment changes 6 .
So far, social distancing is the most effective measure to control the pandemic, conducted through quarantine and vaccines 7 .Thus, further investigation of the psychological effects of this protection measure on the lives of those in social distancing is necessary.Moreover, we should emphasize that the approach of psychological aspects assists in the adherence to control measures such as quarantine 8, 9 .
Despite the strong relevance of psychological aspects in the population, the participation of professionals in mental health in projects related to a pandemic outbreak remains quite limited 9 .Furthermore, quarantine -used for infection control -has received little attention in the literature regarding its psychological effects.
Although the psychological reactions of the population play a critical role in the spread of disease and social disorder during and after the outbreak, the necessary resources are generally not provided to reduce the effects of the impact of pandemics on mental health 8 .
Based on this assumption, this paper aims to analyze the Brazilian and international literature on the effects of the COVID-19 pandemic on the mental health of adults to understand the protective factors and stressors associated with the pandemic and reflect on possible mental health intervention strategies.

Methods
This integrative review of the literature on mental health in the pandemic promotes the synthesis of knowledge through six stages underlying the elaboration process: producing the guiding question; literature search; data collection; critical analysis of the included papers; discussion of results; and, finally, presenting the integrative review 10 .The guiding questions are: 'What aspects affect the mental health of adults because of the COVID-19 pandemic?What are the protective factors and stressors of mental health in the COVID-19 pandemic?'.
We collected data from secondary sources, through a survey of papers in the Latin American and Caribbean Health Sciences Literature (LILACS) and Medical Literature Analysis and Retrieval System Online (MEDLINE) databases, from January to December 2020, the year the new Coronavirus was recognized as a pandemic.We selected papers in English, Portuguese, and Spanish.
The following inclusion and exclusion criteria were used for the selection of papers.Papers that address mental health in the COVID-19 pandemic as the central theme, published in the databases in the defined period in Portuguese, English, or Spanish, were included.The purposeful exclusion criteria were the following: 1. papers that do not address mental health, pandemic, and social restriction; 2. studies that do not address the relationship between psychological factors and restrictive measures; 3. studies in which only secondary results address the issue of mental health; 4. studies carried out with specific populations; surveys with people under 18 years of age; 5. studies with the older adults, subjects with chronic diseases or severely hospitalized subjects.
The search result summary in the researched databases is systematized in the flowchart below (figure 1).When starting the full-text reading of the papers, we noted that 12 of them did not meet the review's objective and were, thus, excluded from the study, leaving out 29 full-text papers for the critical analysis.

Results
Seventeen countries of the 29 papers that make up this review were listed, giving a global scale of the pandemic.This mosaic allowed for diversified research on the effects of the pandemic on mental health from a global perspective, comparing the protective factors and stressors cited in different world regions.
Among the articles selected for the review, seven were from Spain; China and India each had three; the United Kingdom and the United States each had two; and Brazil, Italy, Lebanon, New Zealand, Kuwait, Jordan, Colombia, Canada, Germany, Belgium, Austria, and Ecuador each had one.Most works were quantitative cross-sectional studies due to the need to produce data to assist in planning COVID-19 coping actions.However, cross-sectional studies prevent the use of causal inferences, generating only a hypothesis of possible associations.All studies included subjects of both sexes.
Two thematic lines were established as emerging categories in the analysis of the papers: 1. Mental health stressors; 2. Mental health protective factors.Each paper was analyzed by year of publication, journal, and country of study according to these lines.Moreover, the objectives of each study are also presented.The items mentioned above are systematized in table 1.To assess the effects of quarantine-induced mood changes, implicitly measured through subjective ratings of emotional stimuli.
change of routine, negative perception of the current situation, living alone.
Enjoying working from home, living with other people.

Discussion
We understand health not as the lack of disease, but as biopsychosocial well-being, within an integrative vision.Therefore, it is crucial to understand the factors associated with mental health during the COVID-19 pandemic globally.To this end, we chose two major thematic groups for discussing the papers: 1. Mental health stressors; 2. Mental health protective factors.

Mental health stressors in the COVID-19 pandemic
The mental health aspects investigated in the scientific papers were anxiety, depression, stress, loneliness, and mental distress.
We have majority consensus on the stressors addressed in the literature regarding gender, age, income and work.Schooling level, sharing housing, previous history of health problems, and marital status were also identified as stressors.Thus, 16 papers (55%) mention women A study conducted in India pointed out that the time of lockdown may be associated with increased psychological distress 21 .Routine change imposed by restrictive measures 36,37 , quarantine 30,38 , and greater adherence to stricter recommendations to prevent the spread of the virus 34 were also identified as stressors affecting subjects' mental health.These findings in the review corroborate an initial study that indicated that growing psychological complaints seem to increase with prolonged isolation, in which depressive and anxious symptoms become more susceptible 9 .
Only one study in India pointed to males as the most affected the pandemic 35 regarding mental health.The authors argue that a plausible justification for this result, inconsistent with other studies, may be due to the Indian cultural issue: men do not participate in domestic activities and, due to confinement, responsibilities are being shared between couples.As men are not used to managing their personal, professional, and family lives, the change in the setting may have caused more significant anxiety in this public.
Another stressor was the increase in domestic responsibility.The study showed that women reported a more significant increase in their responsibilities when compared to men 15 .Thus, the intergender difference may be related to societal gender roles.Women who are mothers, for example, may have evidenced higher stress levels due to the interruption of their children's classroom classes 17 .Some justifications were pointed out for the youngest being more vulnerable to mental health problems during the pandemic.Young people are less resilient to adversity and have more difficulties understanding the radical but necessary changes in this pandemic period 26 .Thus, older people are dealing with this atypical situation better than younger people 23 , as they are less likely to have psychological problems and are more stable both financially and emotionally 19 .In the younger population, changes in teaching activities, with the new remote teaching format, seem to have affected emotional stability 17 and educational perspectives 32 , in which being a student became a more significant stressor during the pandemic than in normal periods 24 .A study conducted in the United Kingdom collected data showing that people already at higher risk of loneliness (young adults, low income, and living alone) experienced an even higher risk during the COVID-19 pandemic 24 .It is worth noting that loneliness can be an essential factor in increasing depressive symptoms during the pandemic.Intervention strategies must address aspects that work with loneliness, especially for those who have experienced more significant disruption in their social circle 16 .
Another possible explanation is that younger people may have more access to information about COVID-19 through social media, which can lead to increased stress 28 .A study in Brazil identified that subjects who are more exposed to information about the virus and its victims are at greater risk of having minor mental disorders 12 .Another study of the review conducted in Kuwait identified comparable results, in which higher depression rates were associated with more time devoted to pandemic news 18 .However, researchers from Spain reported that younger adults who spent less time on information had higher hostility, depression, and anxiety rates.Thus, the authors emphasize that lack of and excessive information could be harmful to mental health 33 .Therefore, being informed can be a stressor and a protective factor, depending on the intensity of this consumption 25 .
Although several factors cause stress by interfering with the mental health of adults, some papers have identified factors that protect people's mental health.Understanding these factors facilitates the establishment of intervention strategies for the population's public health, which caregiving health professionals can develop, and public health policies within the scope of this pandemic.
A Chinese paper identified that obtaining psychological and social support is an important strategy to reduce the probability of mental illness generated by loneliness and helplessness that can be exacerbated during quarantine 14 .Connection and social support are protective factors, especially for those who live alone, due to the tendency of loneliness 28 .However, a study conducted in India reported that females' higher stress and anxiety levels than males persisted even after accounting for social support and resilience factors.This finding suggests that gender patterns persist as stressors even after the protective effects have been exercised 15 .
Besides psychological and social resources, physical activity was a strong ally in promoting mental health 23,25,28 , in which exercising more than five times a week helped avoid depression and anxiety 18 .Good sleep quality was also a protective factor in the literature 20,28, 31 .
Enjoying working remotely and having greater flexibility at work were also protective factors 29, 37 .A study conducted in Italy pointed out that working outside the home is associated with greater mental distress levels 13 .This issue may be associated with a higher perception of threat and susceptibility to disease when work is conducted in person, while lower threat levels become a protective factor during the pandemic period 39 .Furthermore, studies have shown that the prevalence of anxiety and depression in the COVID-19 positive group is higher than in the group unaffected by the virus 14 .Having people with COVID-19 close was also pointed out as a stressor by the literature 18,26, 33 .
A study conducted in Brazil identified that being a health professional is 40% less likely to have minor mental disorders.A plausible justification would be greater access to health services and a better understanding of COVID-19 12 .However, another study identified that health professionals are more likely to develop psychological problems due to increased working hours and the need to isolate themselves from family members to avoid contagion 18 .A survey conducted in Spain corroborates this result, as it identified that working outside the home in essential activities during the pandemic is a stressor 26 .
Again, regarding work, people with mild and moderate mental illness are twice as likely to lose their jobs, and unemployment rates for subjects with severe mental disorders are five times higher than people without the disorder; important data mentioned in an Austrian paper 23 .Considering the impact of the pandemic on mental health 13 , interventions aimed at promoting psychological well-being are increasingly necessary.

Final considerations
People subjected to the restrictive measures imposed by the COVID-19 pandemic are vulnerable to mental health problems.However, few studies have evaluated the related psychosocial factors 28 .Despite a topic of strong relevance and global impact, there is still a knowledge gap on the topic.Research on mental disorders during the pandemic is incipient and scarce, especially considering the scientific productions developed in Latin America 20 .
We should assess the diverse groups and their needs to elaborate intervention strategies and public policies in pandemics.For example, young people were considered the most vulnerable in surveys conducted by different countries, and they require attention.Moreover, with a better understanding of risk and protective factors, we recommend that further studies investigate possible coping strategies and selfcare practices that can reduce the effects of the pandemic on mental health.

Figure 1 .
Figure 1.Flowchart for selecting the studies that made up the sample

Table 1 .
Analysis and systematization of the papers underpinning the integrative review