Factors that contributed to Ontario adults’ mental health during the first 16 months of the COVID-19 pandemic: a decision tree analysis

Introduction

Mental health is an integral component of overall health and has been conceptualized by the World Health Organization (2022a) as a state of mind that enables people to recognize their potential, cope with the demands of life, learn and work well, and contribute to their communities. Mental health is not merely the absence of mental illness; rather, it exists on a continuum that consists of the presence and absence of mental illness and mental health symptoms (Keyes, 2002). The ways individuals experience mental health along the continuum vary and can fluctuate in response to changing environments, adverse experiences, and life events (Headey & Wearing, 1989; Peter et al., 2021; World Health Organization, 2022b). Individual, social, and structural factors can interact to protect or undermine a person’s mental health (Oliveros, Agulló-Tomás & Márquez-Álvarez, 2022; World Health Organization, 2022b).

Whereas mental health can be characterized by good behavioural adjustment, the ability to cope with the ordinary stresses of life (American Psychological Association, 2023), the ability to adapt and self-manage, and participation in valued roles (e.g., family, work; Manwell et al., 2015), subjective wellbeing is a distinct construct (Lereya, Patalay & Deighton, 2022) and measures a person’s satisfaction with life as a whole and/or the various domains of life (Cummins, Lau & Stokes, 2004; International Wellbeing Group, 2013). Subjective wellbeing is a component of quality of life, which can include both objective (e.g., the degree of physical disability) and subjective (e.g., perceived stress) dimensions (Cummins, Lau & Stokes, 2004). Though subjective wellbeing encompasses a person’s satisfaction with their health, it also includes a variety of non-health-related domains, such as satisfaction with their standard of living, achievement in life, relationships, safety, community-connectedness, and future security (International Wellbeing Group, 2013); it is the totality of these constructs that makes up a person’s subjective wellbeing (hereafter referred to as wellbeing). It is worth noting that wellbeing has been found to be positively associated with mental health (Grant, Guille & Sen, 2013; Lombardo et al., 2018; Watson & Naragon-Gainey, 2010). Notably, Lombardo et al. (2018) assessed the relationship between mental health and life satisfaction (i.e., wellbeing) and concluded that high life satisfaction was strongly associated with positive mental health among individuals living in Canada. Additionally, in a review conducted by Watson & Naragon-Gainey (2010) the authors found that wellbeing was significantly negatively correlated with depression. Similarly, Grant, Guille & Sen (2013) concluded that individuals who experienced low levels of wellbeing were at increased risk for depressive symptoms. It is thus clear that wellbeing predicts mental health status, such as future depression risk (Grant, Guille & Sen, 2013); however, it is possible for a serious adverse event, such as the COVID-19 pandemic, to depress an individual’s mental health and wellbeing (Cummins, Lau & Stokes, 2004; Headey & Wearing, 1989). Thus, while it is evident that good wellbeing was associated with positive mental health pre-pandemic, it is critical to assess if such intuitive associations persisted in the face of a global pandemic. Notably, given the evolving nature of the COVID-19 pandemic, Martin-Maria, Lara & Forsman (2023) emphasized the importance of studying how the COVID-19 pandemic has affected subjective wellbeing and mental health.

Those exposed to significant adverse events and/or negative individual, social, and structural factors are at a heightened risk of experiencing mental health problems (Canadian Mental Health Association, 2021) and poor wellbeing (Kettlewell et al., 2020). Mental health problems can range from acute, temporary problems such as depression following a stressful event, to severe chronic conditions that disrupt everyday functioning (Scheid & Brown, 2010). In 2018, it was estimated that globally, 506 million adults aged 30–69 years experienced a mental health problem (Institute for Health Metrics & Evaluation, 2023). Anxiety and depression were the leading mental health problems in both adult men and women, with depression being most prevalent (Institute for Health Metrics & Evaluation, 2023). In Canada, the prevalence of mental health problems is concerning as one in five people experience a mental health problem in any given year, and by the age of 40, approximately 50% of the population will experience, or have experienced, a mental health problem (Canadian Mental Health Association, 2021). There is a known relationship between mental health problems and chronic physical conditions (e.g., Canadian Mental Health Association, 2008; Evans et al., 2005; Patten, 1999; Stein et al., 2019), and mental health problems have been identified to negatively impact an individual’s social (Kupferberg, Bicks & Hasler, 2016) and cognitive functioning (Bunce et al., 2008; De Pue et al., 2021) and contribute to the adoption of poor health behaviours (e.g., Canadian Mental Health Association, 2008; Hoang, Kristoffersen & Li, 2019; Parletta, Aljeesh & Baune, 2016).

Public health emergencies, such as the COVID-19 pandemic, can exacerbate pre-existing mental health problems and introduce new challenges, both of which can have long-term impacts (Moreno et al., 2020; World Health Organization, 2022b). For example, many individuals fear infection, long-COVID, and death due to COVID-19, either for themselves or their loved ones (Quadros et al., 2021; Hossain et al., 2023). As a way to mitigate the spread of the virus, in earlier months of the pandemic, public health measures were implemented globally, including national and localized quarantines, lockdowns, restrictions of mass gatherings, physical distancing measures, compulsory mask wearing, and school closures (Ayouni et al., 2021). Though the measures were implemented to protect peoples’ health at a population level, they inadvertently contributed to negative mental health experiences including social isolation, loneliness (McQuaid et al., 2021; Su et al., 2023), feelings of helplessness (Polizzi, Lynn & Perry, 2020), and strained relationships (Ellyatt, 2022). The COVID-19 pandemic also exacerbated global pre-existing inequities, including poverty and unemployment rates (Warren & Bordoloi, 2020), both of which are known risk factors for mental health problems (Weich & Lewis, 1998). Additionally, due to the rapid spread of information, the COVID-19 “infodemic” resulted in the dissemination of false information, including rumors and intentional disinformation, which has undermined individuals’ mental and physical health, and wellbeing (Elbarazi et al., 2022; Rachul et al., 2020; World Health Organization, 2020). Such stressors have led to reported mental health problems at a global level, including psychological distress, depression, anxiety, post-traumatic stress disorder (World Health Organization, 2022b), and poor wellbeing (Elbarazi et al., 2022). Specifically, during the first year of the pandemic, researchers estimated that the prevalence of depression and anxiety increased globally by 28% and 26%, respectively (Santomauro et al., 2021).

While depression and anxiety have increased on a global level, there have been substantial implications at the national level as well. For instance, according to Statistics Canada (2021), one in four adults living in Canada reported symptoms of depression, anxiety, or post-traumatic stress disorder in Spring 2021, compared to the Fall of 2020 wherein the prevalence was one in five. Specifically, the proportion of adults aged 25–44 years who reported symptoms of depression and/or anxiety increased from 18% to 23%, and 15% to 20%, respectively (Statistics Canada, 2021). Further, a greater number of Canadian adults (aged 25–64 years) reported symptoms for at least one mental health disorder from Fall 2020 to Spring 2021 (Statistics Canada, 2021). Of the individuals living in Canada who reported symptoms for at least one mental health disorder, 94% reported experiencing negative impacts related to the COVID-19 pandemic, including loneliness, physical health conditions, and/or relationship challenges (Statistics Canada, 2021). It is important to note that reporting symptoms for a mental disorder does not always indicate the presence of a mental disorder, as the self-report instruments used in the Statistics Canada Survey on COVID-19 and Mental Health measured the prevalence of mental health disorder symptoms and probable diagnoses (Statistics Canada, 2021).

In addition to the probable pandemic-related mental health disorder diagnoses described above, Jenkins et al. (2021) concluded that adults in Canada (n = 3,000) reported a deterioration in mental health during the initial stages of the COVID-19 pandemic (i.e., May 2020). This aligns with findings from Dozois & Mental Health Research Canada (2021), who explored how adults in Canada (n = 1,803) were coping with the COVID-19 pandemic and its impact on experiences of anxiety and depression. While the author did not specify the timeframe during which data were collected, they concluded that since the onset of the COVID-19 pandemic, the number of participants with anxiety and depression increased from 5% to 20% and 4% to 10%, respectively (Dozois & Mental Health Research Canada, 2021). Additionally, Capaldi, Liu & Dopko (2021) compared adults’ self-reported mental health from pre-pandemic (January–December 2019) to the second wave of the pandemic in Canada (September–December 2020). Despite the fact that over half of the participants reported positive mental health, the authors found that, compared to pre-pandemic, there were significantly fewer participants who reported high levels of positive mental health during the second wave of the pandemic (Capaldi, Liu & Dopko, 2021). Building off these findings, Capaldi et al. (2022) investigated whether self-reported positive mental health and perceived change in mental health differed from the second (September–December 2020) to the third (February–May 2021) wave of the COVID-19 pandemic in Canada. The authors found that adults’ mental health deteriorated from the second to the third wave of the pandemic, with fewer participants reporting positive mental health and improved mental health at the latter time point (Capaldi et al., 2022).

It is clear, based on the above review of literature, that the COVID-19 pandemic has negatively impacted the mental health of adults globally; however, less is known regarding the characteristics that contributed to some people having mental health problems during the first 16 months of the COVID-19 pandemic in Ontario, Canada, while others did not. Understanding this is critical, as the first 16 months of the pandemic included ongoing adaptations and restrictions in attempting to mitigate the severity of health issues (Canadian Institute for Health Information, 2022). Of necessity, most of the foci during this period were on developing vaccinations and advocating for preventive measures like physical distancing (Canadian Institute for Health Information, 2022; Chu et al., 2020; Government of Canada, 2020a, 2022b). Of the provinces in Canada, Ontario was among few with strict preventative measures in place during the early months of the pandemic (Dekker & Macdonald, 2022). Thus, understanding the characteristics that contributed to some adults’ having mental health problems during this timeframe, while others did not, is instructive to inform the development of programs/interventions aimed at mitigating the negative impact of the COVID-19 pandemic on adults’ mental health, as well as creating tailored interventions, responsive to the characteristics of those who had the highest incidence of mental health problems. As such, the purpose of this study was to generate profiles of Ontario adults who were more or less at risk for the development of mental health problems during the first 16-months of the COVID-19 pandemic.

Methods

Results

Time point 1 (April 24–July 13, 2020) decision tree

Figure 1 shows the final 3-level model at time 1, comprising 13 nodes, seven of which were terminal subgroups (i.e., nodes that do not split any further). Four predictor variables reached significance (wellbeing, sleep, physical activity, age) and were selected because they best differentiated adults who had mental health problems (79.6%) from those who did not (20.4%) based on the cut scores outlined above. The first level of the tree was split into two initial branches according to participants’ perceived wellbeing, meaning that this variable was the best predictor of mental health status (mental health problems or no mental health problems). The no mental health problems group included participants who had good wellbeing (Node 2), were classified as good sleepers (Node 6), and who were over the age of 42 (Node 12; 72.0% no mental health problems). The probability decreased when participants were 42 years of age or younger (Node 11; 45.3% no mental health problems). Those in the mental health problems group had poor wellbeing (Node 1) and were classified as poor sleepers (Node 3; 93.2% mental health problems). The probability decreased when participants were classified as good sleepers (Node 4) and were not meeting the MVPA recommendations (Node 8; 87.0% mental health problems), and when they were classified as good sleepers (Node 4) and were meeting the MVPA recommendations (Node 7; 75.6% mental health problems). Decision rules for the prediction of mental health problems at time point 1 are presented in Table 1, which also shows detailed “IF–THEN” rules.

Table 1:

Percentage of classification of mental health problems for terminal nodes at time point 1 (April 24–July 13, 2020), by risk probability based on decision rules using the exhaustive CHAID method.

Classification	Node	IF	THEN
1st	3	Participants’ wellbeing was poor AND they were classified as a poor sleeper	93.2%
2nd	7	Participants’ wellbeing was poor AND they were classified as a good sleeper AND they met physical activity (MVPA) guidelines	75.6%
3rd	8	Participants’ wellbeing was poor AND they were classified as a good sleeper AND they did not meet physical activity (MVPA) guidelines	87.0%
4th	9	Participants’ wellbeing was good AND they were classified as a poor sleeper AND they were less than or equal to 56 years of age	71.5%
5th	10	Participants’ wellbeing was good AND they were classified as a poor sleeper AND they were greater than 56 years of age	50.0%
6th	11	Participants’ wellbeing was good AND they were classified as a good sleeper AND they were less than or equal to 42 years of age	54.7%
7th	12	Participants’ wellbeing was good AND they were classified as a good sleeper AND they were greater than 42 years of age	28.0%

DOI: 10.7717/peerj.17193/table-1

Note:

Decision rules displayed in plain text. An example of a lay interpretation is as follows: for the 7th classification/Node 12, IF participants’ wellbeing was good AND they were classified as a good sleeper AND they were over the age of 42, THEN the probability of them experiencing mental health problems was 28.0%.

Time point 3 (July 29–August 30, 2021) decision tree

Figure 2 shows the final 3-level model at time three, comprising eight nodes, five of which were terminal subgroups. Three predictor variables reached significance (wellbeing, sleep, age) and were selected because they best differentiated adults who self-reported mental health problems (76.1%) from those who did not (23.9%). The first level of the tree was split into two initial branches according to participants’ perceived wellbeing, meaning that this variable was the best predictor of mental health status (mental health problems or no mental health problems). The no mental health problems group included participants who had good wellbeing (Node 2) and were classified as good sleepers (Node 6; 63.4% no mental health problems). The probability decreased when participants were classified as poor sleepers (Node 5) and were over the age of 52 (Node 8; 60.2% no mental health problems) and when they were classified as poor sleepers (Node 5) and were 52 years of age or younger (Node 7; 39.9% no mental health problems). Participants in the mental health problems group included participants who had poor wellbeing (Node 1) and were classified as poor sleepers (Node 3; 88.7% mental health problems). The probability decreased when participants were classified as good sleepers (Node 4; 75.8% mental health problems). Decision rules for the prediction of mental health problems at time point 3 are presented in Table 2.

Table 2:

Percentage of classification of mental health problems for terminal nodes at time point 3 (July 29–August 30, 2021), by risk probability based on decision rules using the exhaustive CHAID method.

Classification	Node	IF	THEN
1st	3	Participants’ wellbeing was poor AND they were classified as a poor sleeper	88.7%
2nd	4	Participants’ wellbeing was poor AND they were classified as a good sleeper	75.8%
3rd	6	Participants’ wellbeing was good AND they were classified as a good sleeper	36.6%
4th	7	Participants’ wellbeing was good AND they were classified as a poor sleeper AND were less than or equal to 52 years of age	60.1%
5th	8	Participants’ wellbeing was good AND they were classified as a poor sleeper AND were greater than 52 years of age	39.8%

DOI: 10.7717/peerj.17193/table-2

Note:

Decision rules displayed in plain text.

Discussion

The purpose of this article was to use decision tree modeling to generate profiles of adults who were more or less at risk for the development of mental health problems during the first 16-months of the COVID-19 pandemic in Ontario, Canada. The models yielded profiles based on demographic characteristics and health behaviours/outcomes. From April 24–July 13, 2020 (time point 1), characteristics of those in the ‘no mental health problems’ group included having good wellbeing, being a good sleeper, and being over the age of 42, while characteristics of those in the ‘mental health problems’ group included having poor wellbeing and being a poor sleeper. From July 29–August 30, 2021 (time point 3), characteristics associated with no mental health problems included having good wellbeing and being a good sleeper, while characteristics associated with mental health problems included having poor wellbeing and being a poor sleeper.

Wellbeing was the strongest contributor to mental health status during the first 16 months of the COVID-19 pandemic. In both models (time points 1 and 3), good wellbeing was associated with better mental health (i.e., no mental health problems). This finding is not surprising as wellbeing has been positively linked to mental health in previously published work (Lombardo et al., 2018). Specifically, data collected pre-pandemic (2003–2012) via the Canadian Community Health Survey (CCHS) revealed that life satisfaction (i.e., subjective wellbeing) was strongly associated with self-reported mental health and that individuals (n = 646,471) with poor mental health experienced low life satisfaction (Lombardo et al., 2018). This aligns with findings from the current study, as participants with poor wellbeing (or quality of life per International Wellbeing Group, 2013) were more likely to experience mental health problems at both time points. This might be explained, in part, by the theory of Subjective Wellbeing Homeostasis, which suggests that a person’s wellbeing is relatively stable and that while it can change in the short-term, over time an individual’s wellbeing will return to a baseline level (Cummins, 2010; Headey & Wearing, 1989). However, it is possible for an adverse event (e.g., the COVID-19 pandemic) to negatively impact an individual’s wellbeing, resulting in their baseline level of wellbeing falling below its normal homeostatic range (Cummins, Lau & Stokes, 2004; Headey & Wearing, 1989). This was evidenced by Zajacova et al. (2020), who investigated changes in adults’ (n = 4,627) psychological wellbeing during the early months of the pandemic in Canada. The authors concluded that individuals’ psychological wellbeing decreased significantly from March–May 2020 (Zajacova et al., 2020). Therefore, it is possible that the first 16 months of the pandemic had a negative toll on participants’ wellbeing, potentially contributing to mental health problems.

Experiencing no mental health problems was highest among those who had good wellbeing and sleep (time points 1 and 3), and who were over the age of 42 (time point 3 only), while presence of mental health problems were highest among those who had poor wellbeing and sleep at both time points. These findings are unsurprising as it has been established that good sleep quality is a protective factor against mental health conditions (Scott et al., 2021). Specifically, achieving high quality sleep has been found to reduce risk of depression (Raboch et al., 2017) and lead to improvements in wellbeing (Pilcher, Ginter & Sadowsky, 1997; Prendergast, Mackay & Schofield, 2016). In the same vein, poor sleep quality has been associated with mental and physical distress, anxiety, depression (Strine & Chapman, 2005), and poor quality of life (Baldwin et al., 2001). Since the onset of the COVID-19 pandemic, similar findings have been reported globally. Specifically, Simonetti et al. (2021) conducted a study in Morocco during the early stages of the pandemic (February-April, 2020) and found a positive correlation between anxiety and poor sleep quality among adult nurses (n = 1,005). Similarly, Stanton et al. (2020) conducted a study among Australian adults (n = 1,491) and concluded that negative changes in sleep during the early months of the pandemic (April 2020) were associated with higher levels of depression, anxiety, and stress symptoms. In a study of Norwegian adults (n = 1,281), Ernstsen & Havnen (2021) found that anxiety and depressive symptoms were associated with sleep disturbance during the early stages of the pandemic (June 2020). Moreover, Hyun et al. (2021) investigated the impact of mental health symptoms on sleep quality of young adults (n = 908; aged 18-30) in the United States during the early pandemic (April-May 2020). The authors concluded that young adults experienced high rates of sleep problems and that anxiety and depressive symptoms were predictors of sleep quality (regardless of pre-existing diagnoses; Hyun et al., 2021). This finding aligns with the time point 3 model in the current study, as participants who had good wellbeing and sleep, and who were over the age of 42 did not experience mental health problems. While it is interesting that older age was associated with no mental health problems in the current study, it is not necessarily surprising as data from the 2015–2017 CCHS revealed that older age was associated with positive mental health (Varin et al., 2020). Additionally, Trollor et al. (2007) concluded that age was a significant predictor of mental health problems among their sample of Australian adults (n = 10,641), with increasing age being associated with a lower likelihood of experiencing symptoms of anxiety or affective disorders.

While the same predictor variables reached significance in both models (wellbeing, sleep, age), during the early months of the pandemic (time point 1 only), physical activity (MVPA) appeared to play a significant role with regard to mental health status. Notably, participants who had poor wellbeing, but achieved good sleep and met the Canadian physical activity (MVPA) guidelines were less likely to experience mental health problems (24.4% no mental health problems) compared to those who had poor wellbeing, good sleep, and did not meet the Canadian physical activity guidelines (13.0% no mental health problems). This finding underscores the importance of physical activity in promoting positive mental health; a finding that has been widely reported (e.g., Creese et al., 2021; Jacob et al., 2020; Rebar et al., 2015). However, it is worth noting that the percentage of participants who experienced no mental health problems in this profile was low compared to those who experienced mental health problems, which suggests that participants’ experiences of poor wellbeing might have negatively impacted their ability to engage in physical activity during the early months of the pandemic. This interpretation aligns with findings from a systematic review conducted by Violant-Holz et al. (2020), where the authors investigated whether physical activity was used as a coping strategy early in the pandemic (January 2019–July 2020). The authors concluded that there was an association between mental health distress and physical activity status, such that the pandemic and related public health protections were associated with psychological distress, which might have hindered individuals’ engagement in physical activity (Violant-Holz et al., 2020). Thus, while participants who met the physical activity guidelines experienced fewer mental health problems compared to those who did not meet the physical activity guidelines, wellbeing was a stronger contributor to mental health status than physical activity. It is therefore possible that those who experienced poor wellbeing had a difficult time engaging in physical activity as a result. However, it is also worth noting that there may have been other factors, aside from poor wellbeing, that contributed to participants lack of engagement in physical activity, including the closure of gyms and recreational facilities and demographic factors such as living alone, having low income, and loss of employment due to COVID-19 (Fearnbach et al., 2021), to name a few.

Conclusion

Over the past 3 years, individuals around the world have experienced the pervasive impacts of the COVID-19 pandemic; its health repercussions have been devastating, with illness in varying degrees of severity and deaths that continue to plague populations—and concomitantly, their health care systems—worldwide (Barrett et al., 2020; Pollard, Morran & Nestor-Kalinoski, 2020; World Health Organization, 2023). It has been established that the pandemic has negatively impacted the mental health of adults globally (e.g., McQuaid et al., 2021; Statistics Canada, 2021; Su et al., 2023); but an understanding of the characteristics that contributed to mental health problems during the first 16 months of the COVID-19 pandemic, specifically in Ontario, Canada, were lacking. This study revealed that adults with no mental health problems generally had good wellbeing and sleep quality, and were over the age of 42 years, while participants with mental health problems experienced poor wellbeing and had poor sleep quality. Findings from the current study highlight that wellbeing was the biggest contributor to mental health status during the first 16 months of the COVID-19 pandemic. Future interventions/programs should focus on targeting adults’ wellbeing in order to improve their mental health during times of health crises.

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