RESUMEN
During the COVID-19 pandemic, undergraduate medical students (UMS) exposed to isolation, social distancing and complete or partial face-to-face educational activities interruption may present increased stress, depression and anxiety. This study was undertaken to evaluate if, during isolation, UMS involved in online group activities as investigators of a research project (volunteer group) would present better mental health than their colleagues, not involved in that research (control group). A Web-based survey, via the Google Forms platform, including details on demographic data, life habits, previous health conditions, worries with the COVID-19 pandemic, sleep pattern modifications and depression, anxiety and mental stress, using the DASS-21 (Depression, Anxiety and Stress Scale) was implemented from 20 July to 31 August 2020. Statistical analysis was performed using the SPSS version 20.0. A p-value <0.05 was significant. A total of 684 UMS were included, 228 as a volunteer group and 456 as a control group. Mean age was 23.15 (3.16) years. The groups were paired for age, gender, ethnicity, life habits and previous health conditions. Older age, male gender, participation in the research project, unchanged sleep pattern during the pandemic, lack of fear from getting the COVID-19 and lack of previous health conditions were associated with lower DASS21 scores (better mental health). Participating as investigators of a research project foreseeing frequent interaction with patients, colleagues and professors (other investigators) lead to better mental health during the COVID-19 quarantine in Brazil.