This study examined two cohorts of medical students assessed just prior to and early in the COVID pandemic using a broad range of potential mental health measures. Our study found that: (1) medical school was associated with worsening mental health in a predictable pattern; (2) the COVID-19 pandemic was associated with worsening on many of our measures of mental health, and the pattern across medical school years (see first finding) remained fairly consistent (e.g., the curve was simply pushed upward but retained its shape); and (3) in some instances, the pandemic was related to lower prevalence of some, presumably, negative behaviors such as binge drinking.

Medical school was associated with worsening mental health in a predictable pattern. Looking across the classes of medical school in 2019, we see a predictable pattern with lowest rates at pre-matriculation, rising rates across MS1-MS3 classes, and a return to lower levels at the end of medical school (see Fig 1A-1D). This pattern is consistent with prior work showing higher rates of depression and anxiety among medical trainees, including medical students, residents, and fellows with five to eight times higher rates of depression and anxiety when compared to age-matched US population samples [2]. This suggests that factors intrinsic to medical school contribute to the worsening of mental health [24]. Given this pattern, a focus on curriculum innovations for the MS2 and MS3 classes may help mitigate some of these factors.

The COVID-19 pandemic was associated with worsening of many of the measures of mental health, and the pattern across years remained fairly consistent. For many of the measures, students at pre-matriculation in 2019 and 2021 had similar scores, despite the pandemic. Across medical school classes, the shape of the curve (see previous paragraph) remained similar in 2021 compared to 2019 but was shifted upward. It appears that the impact of the COVID pandemic and medical school together may have contributed to substantial worsening of mental health for many students. These findings are consistent with another study that found a significant decrease in pre-pandemic versus pandemic wellness, even when controlling for medical school class [7]. Many of the life changes that occurred because of the COVID pandemic likely contributed. Medical students experienced a lower sense of purpose as they were labeled as non-essential and removed from the frontlines, especially early in the pandemic [7]. There were difficulties with scheduling board exams, and many important events such as graduation and match day were cancelled due to social distancing restrictions [7]. As classes shifted to virtual, students spent more time at home with less social interactions [7] and felt less connected to their medical school and their classmates [8]. Thus, fostering community, social connectedness, a sense of belonging and meaning/purpose within the medical school community for students might be an important strategy to mitigate mental health concerns seen during the MS2–3 classes.

The pandemic was related to lower prevalence of some, presumably, negative behaviors such as substance use. Both binge drinking and non-cannabis drug use were lower during the pandemic. Possible contributing factors for the decline may be related to a lack of social interaction due to social distancing limitations, possible changes in student’s living environments and less availability of non-cannabis substance use. Recent work supports a general increase in alcohol use during the pandemic among US adults in terms of drinking days [25] and consumption [26]. However, the pandemic impact on binge drinking in young adults is mixed with studies showing both increases and decreases in binge drinking behaviors [27,28]. For medical students specifically, we hypothesize that a reduction of in-person social interactions may be associated with the reported decrease in binge drinking in 2021. This is consistent with prior work linking social interactions with heavier drinking [29]. Our measure of binge drinking is yes/no based on having at least a single occurrence over the past year and thus limited. We have no information on the frequency of binge drinking in this sample [30].

Some measures did not differ in pre-COVID and during COVID comparisons. For example, adverse childhood experiences (ACE) scores were similar across years, consistent with our a priori hypotheses (given that the questions relate to experiences before age 18 we would not expect differences between groups). Although on the surface, such a result might seem simple and expected, it does provide some reassurance that the stress of the pandemic did not lead to over-reporting. For other measures, the outcomes contradicted our a priori hypotheses. For example, scores on obsessive compulsive symptoms remained similar between years despite the increased stress in 2021 (see DASS Stress results).

In summary, the results from this study contribute to the broader literature on medical student mental health generally and the COVID-19 pandemic’s impact on mental health specifically, but our results should be viewed within the context of a few limitations. First, our response rates raise concerns about potential bias, which should be carefully considered when interpreting our results. However, the available literature in this area suffers from the same concern, with some studies having much lower response rates (e.g., 10–12% [9,12]) or being unable to determine response rates [7,11], or conducting online recruitment via social media [7,11]. Thus, within the context of that broader literature, our results add meaningful additional data. Second, this study surveyed students from a single medical school, which may limit generalizability to the broader medical school population; some of the experiences of our students may be idiosyncratic. However, we are reassured that the patterns we observed pre-COVID are in line with the existing literature. Third, the rating scales used in our study asked about functioning over the past 2–4 weeks, which may not have been representative of a participant’s experience over the past year. Lastly because of scheduling, we were not able to have participants complete the surveys on the exact same day across all four classes which may have introduced some variability into the results. Our study also has several strengths. Most notably, this study is unique in collecting the same measures prior to and following the onset of the pandemic. In addition, we present data from students just prior to matriculation and across all four medical school years (some prior studies limited their work to pre-clinical or clinical years), allowing visualization of patterns across medical school years prior to and during the pandemic.