Fear of COVID-19 and illicit drug use during COVID-19 pandemic in Japan: a case-control study.

Background: Some people use illicit drugs to relieve stress. However, these drugs cause serious damage not only to individuals but also to society as a whole. Stress caused by the COVID-19 pandemic is considerable, as the number of illicit drug users continues to increase, despite a decrease in the availability of drugs and opportunities to leave the house during the pandemic. Fear of COVID-19 causes stress; however, its association with illicit drug use is not yet understood. In this study, we examined whether the fear of COVID-19 affects the subsequent use of illicit drugs. Methods: We conducted a retrospective longitudinal case-control study using data from an Internet survey performed annually between 2020-2022, with the 2020 survey as the baseline survey and the 2021 and 2022 surveys as follow-up surveys. Those who were illicit drug use-free at the baseline survey but had a history of drug use upon follow-up were defined as the outcome group, whereas those who remained illicit drug use-free at follow-up were defined as the no-outcome group. Logistic regression analysis was conducted between the two groups, using "the fear of COVID-19" as the explanatory variable and adjusting for the effects of confounding factors. The same analysis was conducted by dividing illicit drugs into cannabis and non-cannabis groups, then setting their use as a secondary outcome. Results: The study included 17,800 subjects, 837 of whom used illicit drugs at follow-up and 16,963 who did not use illicit drugs at follow-up. Logistic regression analysis revealed that higher levels of fear over COVID-19 correlated with higher illicit drug use among the participants. However, our analysis of cannabis-only outcomes showed no significant differences. Conclusions: We found that fear of COVID-19 was a contributing factor to illicit drug use. Although the exact mechanism through which fear influences illicit drug use remains unknown, previous studies have shown that fear of certain targets increases illicit drug use, and our study adds to this evidence. However, in this study, we were unable to show a statistically significant causal relationship between fear of COVID-19 and the use of cannabis alone. Further research on the relationship between fear and the use of cannabis or other drugs, for varying focuses of fear, may broaden our knowledge of the different reasons individuals have for using different drugs.