Background The COVID-19 pandemic is associated with common mental health problems. However, evidence for the association between fear of COVID-19 and obsessive-compulsive disorder (OCD) is limited. Objective This study aimed to examine if fear of negative events affects Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores in the context of a COVID-19–fear-invoking environment. Methods All participants were medical university students and voluntarily completed three surveys via smartphone or computer. Survey 1 was conducted on February 8, 2020, following a 2-week-long quarantine period without classes; survey 2 was conducted on March 25, 2020, when participants had been taking online courses for 2 weeks; and survey 3 was conducted on April 28, 2020, when no new cases had been reported for 2 weeks. The surveys comprised the Y-BOCS and the Zung Self-Rating Anxiety Scale (SAS); additional items included questions on demographics (age, gender, only child vs siblings, enrollment year, major), knowledge of COVID-19, and level of fear pertaining to COVID-19. Results In survey 1, 11.3% of participants (1519/13,478) scored ≥16 on the Y-BOCS (defined as possible OCD). In surveys 2 and 3, 3.6% (305/8162) and 3.5% (305/8511) of participants had scores indicative of possible OCD, respectively. The Y-BOCS score, anxiety level, quarantine level, and intensity of fear were significantly lower at surveys 2 and 3 than at survey 1 (P<.001 for all). Compared to those with a lower Y-BOCS score (<16), participants with possible OCD expressed greater intensity of fear and had higher SAS standard scores (P<.001). The regression linear analysis indicated that intensity of fear was positively correlated to the rate of possible OCD and the average total scores for the Y-BOCS in each survey (P<.001 for all). Multiple regressions showed that those with a higher intensity of fear, a higher anxiety level, of male gender, with sibling(s), and majoring in a nonmedicine discipline had a greater chance of having a higher Y-BOCS score in all surveys. These results were redemonstrated in the 5827 participants who completed both surveys 1 and 2 and in the 4006 participants who completed all three surveys. Furthermore, in matched participants, the Y-BOCS score was negatively correlated to changes in intensity of fear (r=0.74 for survey 2, P<.001; r=0.63 for survey 3, P=.006). Conclusions Our findings indicate that fear of COVID-19 was associated with a greater Y-BOCS score, suggesting that an environment (COVID-19 pandemic) × psychology (fear and/or anxiety) interaction might be involved in OCD and that a fear of negative events might play a role in the etiology of OCD.

BACKGROUND The COVID-19 pandemic is associated with common mental health problems (e.g. fear). Evidence of how the fear of COVID-19 affected obsessive-compulsive disorder (OCD) is limited. OBJECTIVE This study aimed to examine if fear of negative events affects the score of Yale-Brown obsessive compulsive scale (Y-BOCS) in a fear-invoke environment. METHODS All participants were medical university students and voluntarily completed three surveys via smart-phone or computer. Survey 1 was conducted on Feb. 8, 2020 after two-week quarantine without online courses, Survey 2 was conducted on March 25 when participants had been taking online courses for two weeks, and Survey 3 on April 28 when no new case had been reported for two weeks. We used a battery of questionnaire in Surveys, including basic information (age, gender, having sibling, enrollment year, major), knowledge on COVID-19 (0 for ‘do not know’ and 3 for ‘very knowledgeable’, The fear (0 for ‘no fear’ and 9 for ‘extreme fear’), Yale-Brown obsessive compulsive scale (Y-BOCS), and Zung Self-Rating Anxiety Scale (SAS). RESULTS Survey 1 showed that 1519 (11.3%) of 13478 participants scored ≥16 on Yale-Brown obsessive compulsive scale (Y-BOCS), defined as possible OCD (pOCD). Survey 2 and Survey 3 demonstrated 3.6% (305 of 8162) and 3.5% (305 of 8511), respectively. The Y-BOCS score, anxiety level, quarantine level, and intensity of fear were significantly lower at Surveys 2 and 3 than that at Survey 1 (P<.001 for all). Compared to those with a lower Y-BOCS score (<16), participants with pOCD had higher intensity of fear and SAS standard score (P<.001). The regression linear analysis indicated that the intensity of fear was positively correlated to the rate of pOCD and the average total scores for Y-BOCS in each survey (P<.001 for all). Multiple regressions indicated that those with higher intensity of fear, higher anxiety level, are male, have sibling(s), and majored in non-medicine predicted higher Y-BOCS score in all surveys. These results were re-demonstrated in 5827 Survey 1 and Survey 2 matched participants and in 4006 matched participants from three surveys. Furthermore, in matched participants, the Y-BOCS score was negatively correlated to the changes of the intensity of fear (r=0.63 for Survey 2 and 0.74 for Survey 3, P<.01). CONCLUSIONS Our findings indicated that the fear of COVID-19 was associated with the increase of Y-BOCS score, suggesting that environment x psychology interaction might be involved in OCD and that a fear of negative events might play a role in the etiology of OCD.