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An Observational Study to Assess the Impact of COVID-19 on the Factors Affecting the Mental Well-being of Doctoral Students

The effects of SARS-CoV-2 on mental health far extend its effects on physical well-being. Long before the onset of COVID-19, there have been concerns related to the mental well-being of graduate students, especially doctoral students. This study evaluated the factors associated with the mental well-being of doctoral students since the onset of the pandemic using data collected from early career researchers in the UK in April 2020. The results show that the characteristics of mental well-being associated with social connection, loneliness, and anxiety have remained consistent during the lockdowns. Furthermore, everyday stressors related to lifestyle, finances, and caregiving responsibilities, alongside supervisors and university support, influenced the mental well-being of the doctoral students during the pandemic.


Introduction
The COVID-19 pandemic has changed the world in many ways. According to the statements released by the World Health Organization (WHO), COVID-19 "presents an unprecedented challenge to public health, food systems, and the world of work." The pandemic has ravaged the globe claiming millions of lives while disrupting the physical and psychological well-being of numerous across different multitude (Phillips, 2021). Fears of uncertainty related to the unknown, loss of employment, food disruption, lack of healthcare resources, and social isolation continue to impose threats on the psychological well-being of the population. Furthermore, researchers around the world have speculated that the many effects of COVID-19 are about to linger for a much-extended period (Lavine et al., 2021).
Previous research has confirmed the detrimental effects of COVID-19 on marginalized populations, based on race, age, gender, unemployment, and occupation (Alon et al., 2020;Bernstein & Jones, 2020;CDC, 2021;Chapman, 2020;Gould et al. 2020;Venkatesh, 2020). Reports from the Bureau of Labor Statistics indicated that nearly 15% of adults faced unemployment during the pandemic. Cases of violence and abuse against women and children have been on the rise since the onset of lockdown (Petrowski et al., 2021). In addition, one in every four women was affected by an increase in household responsibilities during the lockdowns (Bateman & Ross, 2020). According to the Centers for Disease Control and Prevention (CDC), ethnic and racial minority groups had a higher prevalence of certain mental illnesses, substance abuse, and lack of health care during the pandemic (McKnight-Eily et al., 2021;Tai et al., 2021;Wilder, 2021). However, the greatest impact of isolation and loneliness was on the elderly population (Wu, 2020) and people with disabilities (Lebrasseur et al., 2020). Lack of access to health care further intensified the already existing challenges for the ones with disabilities (Lebrasseur et al., 2020).
Even before the onset of the pandemic, the mental health of researchers, particularly that of doctoral students, had been a point of concern (Else, 2021;Nagy et al., 2021;Scott & Takarangi, 2019). Academic settings often impose mental health stressors such as depression, anxiety, periods of intense stress, burnout, and imposter syndrome (Makani, 2021). Furthermore, about one-third of 6300 early career researchers reported to sought help during their doctoral studies (Byrom, 2020;Woolston, 2019). Additionally, the pandemic has introduced many new challenges, further worsening the situation. For instance, according to Wasil et al. (2020), COVID-19 has doubled the signs of depression and anxiety.
Though many studies examined the factors influencing the mental health of early career researchers and graduate students during the COVID-19 lockdowns (Browning et al., 2021;Wasil et al., 2020;Woolston, 2020), not many focused on the mental health of doctoral students. This study aims to bridge that gap. Studies have shown that an encouraging environment significantly improves student success (Baeten et al., 2010;Ivankova & Stick, 2007). Therefore, through this study, we aim to identify the influential factors that affect doctoral students' mental health which would help universities and supervisors develop strategies to support the emotional and intellectual needs of their students, thus improving student experience, and subsequently student success (Saavedra et al., 2018).

Study Population
This study's data set was obtained from a cross-sectional survey conducted by Smarten and Vitae to assess the consequences of COVID-19 on mental well-being, research work, and social connections. The data can be accessed online via Figshare, an online platform for collaborating on scientific data and results (Byrom & Metcalfe, 2020). The survey was conducted in April 2020, during the initial breakout of COVID-19, which was rapidly followed by a subsequent series of lockdowns. This study is based on 4274 doctoral students from a survey of 5902 early career researchers. To ensure participant anonymity, respondent identification was removed by the original authors of the data set. Informed consent was obtained from all individual participants included in the study by the original authors of the data set.

Measures: Psychological Scales
Psychological scales used in this study include: • Warwick-Edinburgh Mental Well-being scale (WEMWBS): As a measure of mental well-being, the 7-item WEMWBS was considered. The 7-item WEM-WBS is used to assess subjective well-being and psychological functioning. A WEMWBS raw score is usually constructed by summing the responses of seven questions, whose responses range from 1 (none of the time) to 5 (all of the time). Thus, the corresponding range of WEMWBS raw score is 7-35. Instead of using the raw score in the analysis, Warwick Medical School (2007a) recommends using the WEMWBS score. A lower value of transformed WEMWBS score is interpreted as lower chances of negative mental well-being (Warwick Medical School, 2007b). • UCLA 3-item Loneliness Scale: Aspects of loneliness are effectively measured using the 3-item UCLA loneliness scale. The responses to the three questions include three categories: 1 (hardly ever), 2 (some of the time), and 3 (often). Thus, constructing the range of the UCLA loneliness scale from 3 to 9. The higher the UCLA score, the greater the chances of loneliness or social isolation (Russell et al., 1978). • K-6 Distress Scale: The 6-item Kessler psychological distress scale is a measure of mental distress and helps screen for mental health issues like anxiety and depression. The scale has six questions that measure the various reactions to distress, including nervousness, hopelessness, restlessness, jitteriness, sadness, and feeling of being worthy. The response to each of these six questions is on a 5-point Likert-type scale of 0 (none of the time) to 4 (all of the time); thus, the resulting distress score ranges from 0 to 24. Higher values of distress score indicate a higher risk of psychological distress (Kessler et al., 2003).

Methods
Prior to data analysis, this study conducted data pre-processing and exploration using SAS software, version 9.4. Data cleansing and removal of missing values were a part of data pre-processing. All analyses were conducted at a 0.05 significance level (α).

Independent Variables
Variables in the data set included questions related to (a) psychological scores: UCLA loneliness, and K-6 distress; (b) social connection to peers and/or colleagues; (v) socio-demographic characteristics; and (w) disability status. Out of 127 variables from the original data set, 27 were considered as independent factors or characteristics in this study. Some of these 27 characteristics include aforementioned psychological scores. Records with missing data were removed prior to data analysis. A total of 778 records were eligible for data analysis.

Covariates
Age, gender, and ethnicity were considered as covariates in the study since these characteristics often reveal a distinct trend across different subgroups (Barnard, 2013;Khumalo et al., 2012). Gender was merged into three possible categories: male, female, and others due to its sparse population across different subgroups, while ethnicity was recategorized into White, Asian, Black, and others.

Dependent Variable
WEMWBS score was the outcome of interest in this study.

Exploratory Data Analysis
Exploratory data analysis was the first step to the data analysis. Distribution of individual predictors was assessed using summary statistics, boxplots, and scatterplots with respect to the WEMWBS score. Furthermore, the Pearson and Spearman correlation coefficients were used to assess the correlation between the possible predictors.

Association Between the WEMWBS Score and the Independent Variables
To analyze the relationship between the WEMWBS score and individual predictors, generalized linear models (Kutner et al., 2013) were used and the unadjusted estimates along with 95% confidence intervals (CI) were calculated. Using potential covariates such as age, gender, and ethnicity in the model, the adjusted estimates along with 95% CI were calculated. Model assumptions were then assessed using residual analysis, followed by evaluating the model's multicollinearity using variation inflation factor (VIF). To add a step further, the stepwise selection method was added as a part of the data analysis. Stepwise variable selection is a method that aims to find the most significant predictors in the model. Power calculations showed that the models had more than 80% power. Figure 1 shows the flow diagram of this study. The flow chart illustrates the record counts at each phase of the study.

Dependent Variable
The exploratory analysis confirmed that the outcome, WEMWBS score, was normally distributed with six potential outliers. Table 1 represents the five summary descriptive statistics for the WEMWBS score.

Mental Well-being and the Independent Variables
Tables 2, 3, and 4 show the association between the WEMWBS score and the individual characteristics considered in this study. Age was found to be statistically significant among the socio-demographic characteristics. Gender was found to be borderline significant while disability status and ethnicity were not statistically significant.  Among the other characteristics, the statistically significant characteristics were as follows: (a) student status (part-time or full-time); (b) end date of current funding; (c) social connection; (d) influence of lockdown on social contact; (e) change in relationship with university; (f) impact on finances for the next academic year; (g) impact of caregiving responsibilities on work; (h) impact on work; (i) impact on research tools; (j) university support; (k) supervisor support; (l) everyday stressors related to family, lifestyle, and employment; (m) feelings of loneliness; and (n) feelings of distress. However, adjusting for the covariates, student status was no longer significant. When corrected for multiple comparisons using Benjamini-Hochberg (BH) adjustment, no significant differences in the association between the WEMWBS score and the independent characteristics were identified (adjusted p-value not included).
The results from the stepwise selection method showed similar results. Using SBC as the default stopping criterion, the stepwise selection method indicated social connection as the most influential factor affecting the mental well-being of doctoral students, followed by caregiving responsibilities, feelings of distress, and loneliness. Furthermore, everyday stressors related to family, lifestyle, and employment were also identified to be significantly impacting doctoral students' mental health.
Residual analysis of the individual and the stepwise selected generalized linear model showed that none of the model assumptions was violated. Additionally, outlier analysis showed that none of the outliers was influential. Though Pearson and Spearman correlation coefficients indicated that social connection and influence of lockdown on social contact are correlated alongside feelings of loneliness and distress, the VIF value from the stepwise selected model showed that multicollinearity was not prevalent in the model (data not included).

Discussion
The results from this study confirm that the key determinants affecting the mental health of doctoral students have not altered significantly since the pandemic. Personal and academic isolation related to loneliness, distress, and social connection were identified as the primary factors threatening the psychological well-being of doctoral students in the past. Studies conducted prior to COVID-19 (Akhter & Khalek, 2020;Janta et al., 2014) identified loneliness and social connection as important elements affecting the mental health of doctoral students. Alongside the stress of academia, the global lockdowns during the initial outbreak of COVID-19 majorly disrupted the social connections with peers, friends, and family, thus, magnifying the feelings of loneliness and distress, eventually impacting the mental well-being of doctoral students.
This study was able to identify university and supervisor support alongside the impact on finances as the characteristics that affected the mental health of doctoral students. Factors like organizational support, supervisor interactions, and deadline stress were also highlighted as factors of major concerns in the past studies (Akhter & Khalek, 2020;Saavedra et al., 2018;Scott & Takarangi, 2019).
Unlike some of the past studies, the results did not deem changes in deadlines, and caregiving responsibilities as a significant characteristic associated with the mental health of doctoral students. The possible explanation could be related to the online mode of study, where universities and supervisors have been more flexible with deadlines (Armstrong-Mensah et al., 2020), thus, making it easier for students to manage stress at home and school. Moreover, changes in caregiving responsibilities had major class imbalances; thus, there is a possibility that the true association was not captured.
The impact of caregiving responsibilities on work and everyday stressors related to family, lifestyle, and employment was identified as significant predictors. Some studies reported that doctoral students would frequently feel burned out between household and employment responsibilities (Breitenbach et al., 2019;Woolston, 2019). As a result, graduate students would often indulge themselves in physical activities, such as exercise and cycling, or stress-relieving activities, such as yoga (Kumar & Cavallaro, 2018). However, with the subsequent lockdowns during the initial phase, outdoor activities and gyms were completely shut down which could have eventually led to more stress, thus, increasing the chances of deteriorating mental health.
The results from this study show that gender was borderline significant; thus, no comment could be made on the association of doctoral students' mental well-being with gender, whereas past studies were able to identify distinct discrimination based on gender and sexuality when assessing doctoral students' mental health (Else, 2021;Woolston, 2019). This could be related to the fact that the majority of the survey respondents were females. The percentage of other gender category, such as the subgroups representing LGBTQ+, was very low. Therefore, the impact of COVID-19 on marginalized gender categories could not be confirmed. Also, the survey did not collect any information on the sexuality of the respondents; thus, no valid conclusion could be drawn on the same.
The study result demonstrated age to be influential on the mental health of doctoral students. Reports have confirmed that the elderly population was the most afflicted by the pandemic (Wu, 2020); however, this could not be confirmed by the study since the percentage of adult respondents above 70 years was very small.
The strengths of this study include its fairly high sample size and the availability of several characteristics related to both the academic and social lives of doctoral students. One of the weaknesses of the study was the unbalanced data across multiple groups. The study's validity could be enhanced further by employing imputation methods to treat missing values rather than eliminating observations. Further, due to data unavailability, the study was unable to analyze the true association across different age categories (such as those under 20 or over 70) or ethnic groups other than White, Black, and Asian. Also, the study did not investigate the interaction across different characteristics.
Since this study is based on the data collected during the initial phase of COVID-19, some social factors may have been altered with global vaccination in place and the pandemic lasting more than a year. Also, the respondents of this survey were primarily based in the UK and might not have captured diverse socio-demographics.

Conclusion
Future studies could be conducted by consolidating data from all over the world to evaluate the pandemic's global consequences on the mental health of doctoral students. Since few studies have focused on marginalized population groups based on disability and the LGBTQ+ community, the potential future scope of work could be extended to the mental well-being of doctoral students within such closed population groups. Understanding the concerns and challenges of these minority groups, which are often at a higher risk of compromised mental health, would help universities and supervisors prepare themselves to support the unique needs of doctoral researchers across all spectrums.