Prevalence of Depression and Associated Factors among Medical Students in a Southern Nigerian University

Introduction: Medical students may be vulnerable to depression and other psychiatric morbidity. This study sought to assess the prevalence of depression and associated factors among medical students in Niger Delta University, Bayelsa State, Nigeria. Methods: Using a self-administered, author-developed questionnaire with adaptations from the Patient-rated version of Mini-International Neuropsychiatric Interview (MINI-PR) and the Depression Anxiety Stress Scale (DASS), data including socio-demographic characteristics, alcohol use/abuse, cigarette smoking, features of depression and anxiety were collected from 243 medical students in this descriptive cross-sectional study over a period of 4months. Results: Of the 243 participants, 52.7% were male, mostly aged 18 to 24 years (67.1%). The incidence of depression, suicidal ideation, alcohol use, and psychoactive substance use as defined by the MINI questionnaire was 30.5%, 14.8%, 14.8%, and 9.9%, respectively. As defined by DASS 21, almost a third suffered different levels of anxiety (29.6%), and less than one-fifth reported different levels of stress (17.7%). Female gender and year of study showed a significant association with the diagnosis of depression (X=15.75;p–0.008). Living arrangement (X=11.43;p–0.022), perception of accommodation condition (X=16.35;p–0.001), academic performance (X=18.02;p–0.001), and experience of academic failure (X=5.13;p–0.023) all had a significant relationship with depression among the study population. Conclusion: Prevalence of depression among medical students is high; its diagnosis showed a significant association with female gender, year of study, and perception of social and academic factors. Several comorbid psychiatric conditions may coexist with depression among medical students; therefore, the approach to their mental health should be holistic with attention paid to associated factors and psychiatric comorbidities.


Introduction
Depression is a clinical condition characterized by a sad mood, reduction in energy levels and activity (anergia), loss of interest in pleasurable activities (anhedonia), sleep disturbances and pessimism, amongst others (Maj et al., 2020). It is also associated with an increased risk of suicide. It usually begins at a young age and runs a chronic, recurrent course with female preponderance (Marcus et al., 2020). Depression is among the leading causes of global morbidity and mortality, with a lifetime prevalence of about 5-10% in most countries. The World Health Organization estimates that about 350 million people suffer from depression globally. By 2020, it is estimated that depression will be the second most burdensome disease worldwide as measured by the Disability Adjusted Life Years (World Health Organization, 2001). It causes great suffering and economic loss to those affected and to society at large. There is also an increasing prevalence of depression among young people (Mojtabai et al., 2016;Juma et al., 2020). A comparison of mental health problems in higher education students in the United Kingdom of 2015/2016 with 2006/2007 found that the number of students disclosing mental health problems increased fivefold, and university deaths by suicide increased by 79% (Thorley, 2017).
Medical students are believed to be at increased risk of depression compared to other students and the general population Dyrbye et al., 2016). Studies from different parts of the world have shown an increased prevalence of depression among medical students (Puthran et al., 2016;Roh et al., 2010;Onyishi et al., estimated minimum sample size is true for populations greater than 10,000. The total population of medical students in the university was estimated to be about three hundred students, with an average of fifty students in each grade of student. Therefore, the sample size is adjusted using a correction formula for desired sample size calculation when a population is less than 10,000 (Bartlett et al., 2001;Mahajan et al., 2010). This is expressed as: where, n = adjusted sample size; N 0 = sample size estimate for population size greater than 10,000 (275); N = Total population of persons with the variable of interest who are the medical students (300 students). Substitution yielded a minimum sample size of 143 participants for the study. We also corrected for non-response using a non-response rate of 20%. The 20% of 143 is approximately 29; hence the final minimum sample size of 172 was obtained for the study. However, we eventually sampled a total of 243 medical students at NDU.

Sampling Technique
A probability sampling technique, simple random sampling (balloting) was deployed to recruit participants from each level of study. The number on the class attendance register was used to represent each member's unique identifier for the study.

Study Instrument
The study instrument for this study was a 3-section questionnaire developed by the researchers with a total of 82 items comprising of different validated tools which have been used in different settings to assess depression and associated factors. Section One of the study tool collected data on socio-demographic characteristics, level of study, living arrangement, accommodation conditions, socioeconomic class, financial pressure, and academic performance of participants. Section Two contained the Patient-rated version of Mini-International Neuropsychiatric Interview (MINI-PR) (Roh et al., 2010, Sheehan et al., 1998, Aguocha et al., 2015 exploring features of depression, suicidal ideation, alcohol, and substance use/abuse. This was used to diagnose depression among participants. The Depression Anxiety Stress Scale (DASS) investigates the levels of stress and anxiety among participants and forms the Section Three of the study tool. These instruments have been widely used and validated in the assessment of depression, substance/alcohol use and abuse, anxiety, and stress in our locality ((Roh et al., 2010;Sheehan et al., 1998;Aguocha et al., 2015;Lovibond et al., 1995;Oladiji et al. 2009).

Study Procedure
Two trained research assistants in collaboration with the two principal investigators collected data for the study. The research assistants were recruited from medical officers working in the Internal medicine department of the Niger Delta University Teaching Hospital (NDUTH). The training involved explaining the different items on the questionnaire to the research assistants to ensure they understood the response each item on the questionnaire was designed to elicit. The objectives and procedure for sampling and seeking consent for the study were also enumerated during the training. Before the data collection proper, the various class representatives were intimated with the objectives, purpose, and benefit of the study, hence their support was secured, and they helped organize class members who had the questionnaire administered to them during their breaks.
The questionnaires were given to the recruited members of each class to self-administer it on themselves. On the return of the questionnaire, each questionnaire was cross-checked to make sure it was properly filled. Each questionnaire took no more than 15 minutes to complete. Research assistants who had been trained by the authors and the authors themselves were available to assist participants where necessary in filling the questionnaires. Anonymity and confidentiality were upheld. The questionnaires were pretested prior to the commencement of the study at the University of Benin among 3rd year medical students to further ensure the reliability and validity of the questionnaire.

Data Analysis
Data were analyzed using the Statistical Package for Social Sciences version 23 (SPSS 23) (Bryman & Cramer 2013). Categorical variables were summarized in frequencies and percentages, and relationships between socio-demographic characteristics, financial pressure, living arrangement, academic performance, and depression were explored using the Chi-square tests of proportion. The level of significance was set at ≤ 0.05 (at 95% Confidence Interval).

Ethical Issues
The study was conducted in accordance with the Helsinki declaration, (World Medical Association Declaration of Helsinki. 2013) and ethical clearance was obtained from the Research and Ethics committee of the Niger Delta University Teaching Hospital. Voluntary written informed consent was obtained from the study participants. All data was handled with strict confidentiality.

Socio-Demographic Characteristics of Participants
Of the 243 participants in the study, 52.7% were male medical students, and most were aged 18 to 24 years (67.1%), single (94.2%), Christian (97.5%), and in the first year of study (24.3%). Table 2 revealed that most students live in the hostel (42.0%) and consider their accommodation conditions fair (49.0%). About half think they suffer moderate financial pressure. While 43.2% of the study population considers their academic performance of average standard, about a third has experienced academic failure in medical school (32.9%). Table 3 shows that the incidence of depression, suicidal ideation, alcohol use, and psychoactive substance use as defined by the MINI questionnaire is 30.5%, 14.8%, 14.8%, and 9.9%, respectively. The incidence of other classifications of these medical conditions is shown in Table 3. Table 4 highlights the incidence of depression, anxiety, and stress as defined by the DASS 21 questionnaire. Depression as defined by DASS 21 is seen in about a quarter of participants, while almost a third suffer different level of anxiety (29.6%), less than one-fifth reported different levels of stress (17.7%). Table 5 shows the relationship between depression and socio-demographic characteristics of the study participants. Female gender and the year of study show a significant association with the diagnosis of depression (X 2 =3.80; p -0.051, X 2 =15.75; p -0.008, respectively). Table 6 reveals that living arrangement (X 2 = 11.43; p -0.022), perception of accommodation condition (X 2 = 16.35; p -0.001), academic performance(X 2 = 18.02; p -0.001) and experience of academic failure (X 2 = 5.13; p -0.023) all have significant relationship with depression among the study population.

Discussion
Stressors such as higher academic requirements, social and emotional adjustments, new found independence, socioeconomic challenges, and time management pressure may be associated with university learning (Mutambara & Bhebe, 2012, Rice, 2009. Medical students, in particular, are typically faced with these and several other challenges, including; a large academic workload, several qualifying examinations that determine whether or not they proceed to clinical classes, in addition to the pressures of the clinical environment (Moir et al., 2018;Brazeau et al., 2014;Oku & Owoaje, 2015;Martin, 1997;Sreeramareddy et al., 2007;Gureje et al., 2006). The present study found that major depressive episodes, suicidal ideation, alcohol use, and psychoactive substance use among medical students were 30.5%, 14.8%, 14.8%, and 9.9%, respectively, as defined by the MINI questionnaire among study participants. The patient-rated version of Mini International Neuropsychiatric Interview (MINI-PR) used to diagnose depression among participants in this study is widely used and validated instrument (Puthran et al., 2016;Sheehan et al., 1998;Aguocha et al., 2015).
The incidence of major depressive episodes (MDE) in the medical students in this study is at least ten times higher than the general population (Gureje et al., 2006) with results from the Nigerian Survey of Mental Health and Well-being (2002Well-being ( /2003 showing lifetime and 12-month estimates of MDE of 3.1% and 1.1% respectively in the general population (Gureje et al., 2006) and the MDE found to be highly comorbid with anxiety disorder. A review of studies from 1990 and 2010 reporting on depression prevalence among university students suggests they experience rates of depression substantially higher than those found in the general population with reported prevalence rates ranging from 10% to 85% with a weighted mean prevalence of 30.6% (Ibrahim et al., 2013). A recent meta-analysis showed depression affected approximately a third of medical students worldwide, and other psychological difficulties, such as anxiety, suicidal thoughts, burnout, and substance abuse, may accompany depressive symptoms in these students (Rotenstein et al., 2016). This is similar to findings in the present study, which showed almost a third of the medical students suffered different levels of anxiety (29.6%) while less than one-fifth reported different levels of stress (17.7%) as defined by DASS 21.
A comparison of mental health problems in higher education students in the UK of 2015/2016 with 2006/2007 found that the number of students disclosing mental health problems increased fivefold, and university deaths by suicide increased by 79% (Thorley 2017). Medical students are required to assimilate tremendous amounts of information, spend more years in training than their peers in most other disciplines, recall information from prior courses and score high grades in continuous assessments and examinations (Rotenstein et al., 2016). Some may struggle with the large medical curriculum, and these pressures may result in psychiatric morbidities (Falade et al. 2020). The present study found that perception of academic performance and the experience of academic failure had significant relationships with depression among the study population. This finding is similar to previous studies in both medical and non-medical students (Nwobi et al., 2009;Aniebue & Onyema, 2008;Falade et al., 2020;Khan et al., 2018). , Falade et al. 2020 in a study involving 944 medical students found a 25.0% prevalence of psychiatric morbidity among the respondents, and associated independent factors also included; being a student of a private institution, average academic performance, and below-average academic performance. Using a gjhs.ccsenet.org Global Journal of Health Science Vol. 13, No. 12;2021 20 cross-sectional design, Khan et al. (2018) collected data on several stressors psychiatric morbidities from 379 students. The stressors included workload, emotional and interpersonal demands, while the psychiatric morbidities included depression, anxiety, and social dysfunction. They found the perceived stressors and symptoms of mental illness were negatively related to the students' academic performance.
Living arrangements and perception of accommodation conditions were also significantly associated with depression. Our findings are also similar to previous findings by Nwobi et al. (2009);and Aniebue, and Onyema (2008) who also found depression prevalence was also associated with the perception of inadequate accommodation. Research shows satisfaction with one's living environment provides a buffer against poor mental health in everyday life, while dissatisfaction with accommodation/living arrangement can pose a significant risk to a person's mental health (World Health Organization & Calouste Gulbenkian Foundation, 2014).
In assessing the relationship between depression and socio-demographic characteristics of the study participants, both female gender and year of the study show a significant association with the diagnosis of depression. Similar to our study, which found depression was common in the lower classes, several studies report higher depression and stress among students in the lower classes, especially the first and second years of study (Roh et al., 2010;Onyishi et al., 2016;Zoccolillo et al., 2006;Basnet et al., 2012) possibly because they are new in the system and still adjusting to the academic pressure. In a survey carried out among the undergraduate medical students in Nepal (Basnet et al. 2012), the prevalence of depression in the first and third year was 36.74 and 22.22 percent, respectively. Both the first and third-year students attributed mostly academic stress and a hectic lifestyle as the major stress-inducing factors (Zoccolillo et al., 2006). However, students are likely to learn to adopt active coping strategies such as positive framing, leisure activities, talking to family and friends, and exercising (Pierceall et al., 2007;Bamuhair et al., 2015) to deal with stress, by their final year of medical school than in earlier years (Puthran et al., 2016).
Contrary to this, some researchers suggest that the mental health of medical students' declines with increasing years of study and continues to decline as trainees enter the workforce (Aguocha et al., 2015). A meta-analysis by Dyrbye et al2005 showed that medical students at the start of medical school have similar mental health profile as their non-medical peers (Dyrbye et al., 2005;Carson et al., 2000). The decline in higher years and even post qualification decline may be attributable to various sources of stress, some of which include the increased academic workload, concern for academic performance, and the pressure of several qualifying examinations that determine academic and career progression (Sheehan et al., 1998;Guthrie et al., 1995;Cohen et al., 2005).
Similar to our findings, several studies show gender differences in the diagnosis of depression, with female medical students experiencing more depression than males (Singh et al., 2010;Nwobi et al., 2009;Aniebue & Onyema, 2008;Dahlin et al., 2005. The trend that females medical students experience more depression than males may be because they tend to be more concerned about working hard to secure higher marks in exams, are more competitive and concerned about their academic performance, may exaggerate their sadness, and tend to be less engaging with exercise (Inam et al., 2003;Zaid et al., 2007).
The incidence of suicidal ideation among medical students in the present study was 14.8%. Suicidal ideation refers to thoughts about suicide, that may deliberately be constructed to fail or be discovered or may fully be intended to succeed (Aqeel et al., 2014). Globally, suicide is among the top three leading causes of death in men and women aged 15 -44 years, accounting for nearly one million deaths annually (van Niekerk et al. 2012). This represents an annual age-standardized suicide rate of 11.4 per 100 000 population globally and 6.11 per 100 000 population for Nigeria (Adewuya et al., 2016). A previous study in the general population in Lagos, Nigeria showed a 7.28% prevalence of suicidal ideation with independently associated factors being older age, female, single status, low socioeconomic status, depression, somatic symptoms, anxiety, and disability (Schernhammer, 2005). Prevalence of suicidal ideation and suicidal attempt tends to be at least 2-10 times higher in medical students compared to age matched general population (World Health Report, 2003; WHO Mortality Database Documentation May 2013. Medical students have a higher risk of suicidal ideation, suicide, burnout, and a lower quality of life than age-matched populations (World Health Report, 2003;Ayala et al., 2017;Jahrami et al., 2019;Jahrami et al., 2020).

Limitations
Responses depend on the truthfulness of the respondents.

Conclusion
The prevalence of depression among medical students is high. It is more prevalent in the lower (entry classes) medical classes and in female students. Several comorbid psychiatric conditions may also coexist with depression in medical students, and approach to their mental health should be holistic with attention also paid to associated factors and psychiatric comorbidities.

Data Sharing Statement
The datasets analyzed during the current study are available from the corresponding author on reasonable request.