Course of Obsessive–Compulsive Symptoms during the Pandemic
Several studies assessed OCD severity at multiple timepoints, both in clinical and non-clinical samples.
Longitudinal studies with clinical samples generally recruited patients with OCD being seen in specialty care settings and compared Yale-Brown Obsessive–Compulsive Scale (Y-BOCS) [7,8] scores or other validated assessments from before the pandemic with their symptoms during the early stages of the pandemic. Three studies with adults and one with youth found significant increases in OCD severity during the early stages of the pandemic compared with prior to the pandemic using validated symptom assessments (ns = 127 [9••]; 30 [5•]; 270 [10••]; 61 [11••]). In contrast, one study found improvement from treatment initiation to just prior to the pandemic to just after the pandemic began and found no difference in OCD symptom course compared with another cohort followed at their clinic a year earlier (n = 240) [12••]. Another study found a lack of change in OCD symptoms among youth, though this was conducted with a smaller sample (n = 29) and used a single-item rating rather than a gold-standard assessment .
A more common approach in evaluating symptom course during the pandemic was through asking individuals with OCD whether their symptoms worsened during the pandemic. Studies recruited patients actively involved in treatment in specialty clinical settings or online/through prior participation in OCD research. In the clinical studies, estimates of worsened symptoms were 6% (n = 84) , 10% (n = 60) , 12% (n = 113) , 32% (n = 65) , 36% (n = 123) [17•], 45% (n = 65) , and 65% (n = 127) [9••]. The pooled rate was calculated to be 32% (95% CIs 28–35%). Notably, two of the three studies with the highest estimates of worsened symptoms were from studies conducted in Italy during the early stages of the pandemic, which was among the most severely impacted nations [9••, 17•]. One study with youth with OCD (n = 29) found that significantly more were rated as “improved” on the Clinical Global Impressions (CGI)-Improvement Scale (45%) than those who were “worsened” (10%), with no significant change in CGI-Severity Scale scores across assessments [11••]. Experienced exposure and response prevention clinicians provided an estimate near the middle of this range, reporting that approximately 38% on average worsened during the pandemic (n = 137 clinicians) . Rates of worsening were higher in the online samples, including 36% (n = 47) , 73% (n = 37) , 76% (n = 394) [21•], 76% (n = 252) , 93% (n = 196) , resulting in a pooled estimate of 77% (95% CIs 75–80%).
A small number of studies also assessed obsessive–compulsive symptoms prospectively across multiple timepoints during the pandemic in non-OCD samples, yielding less consistent findings. In one large university sample in China (n = 5,827), estimates of elevated OCD based on self-report Y-BOCS scores in February, March, and April, 2020 were 11.3%, 3.6%, and 3.5%, respectively [24•]. Another study with college students also found OCD symptoms decreased from before the pandemic, to mid-lockdown, to after the lockdown in Italy . In contrast, Loosen and colleagues [26•] assessed obsessive–compulsive symptoms in 406 adults in the UK in April/May, 2020 and again in July/August, 2021, finding significantly increased obsessive–compulsive symptoms. Similarly, OCD symptoms were also observed to increase from pre-pandemic to the early stages of the pandemic in youth with neuropsychiatric disorders . A final study found that adults with ASD (without OCD) were not found to have significantly greater obsessive–compulsive symptoms from before to after the lockdown using a brief screener .
More broadly, several studies found higher-than-expected rates of clinically elevated OCD in the general population using established cut-point on the Obsessive–Compulsive Inventory-Revised, including 12% in Portugal in March (29) and 21% in Germany in March/April  or when comparing symptoms with norm values in China in February (31) as well as in the UK in April/May and July/August [26•].
Impact of Contamination on Symptom Severity, Course, and Other Outcomes
A number of studies that assessed individuals with OCD evaluated the impact of contamination symptoms on symptom severity and course.
Six studies found evidence for a poorer course for those with contamination symptoms, including three that found having contamination-related OCD prior to the pandemic predicted greater increases in overall symptom severity during the pandemic (ns = 30 [5•], 127 [9••], and 394 [21•]). Importantly, this was the case in two longitudinal studies investigating this question [5•, 9••]. Similarly, a longitudinal study with youth found significantly higher rates of contamination symptoms but not other dimensions during the pandemic [11••]. In their prospective study of patients with OCD (n = 270), Khosravani and colleagues found that OCD symptoms worsened in all domains, including contamination as well as symmetry/completeness, harm, and unacceptable thoughts [10••]. Although all domains significantly worsened, effect sizes appeared largest for contamination and comparisons of whether increases were greater for the contamination group were not conducted. A retrospective evaluation (n = 196) found higher worsening in those with contamination compared with symmetry symptoms (though no differences with harm or unacceptable thoughts were noted) . A study of patients with remitted or partially remitted OCD found that all patients with worsened OCD during the pandemic (based on repeated Y-BOCS administrations) had a primary contamination presentation .
In contrast, five studies did not find evidence for differences in course among those with contamination symptoms. This included one longitudinal study (n = 240) [12••], three retrospective studies (ns = 113 , 123 , and 65 [17•), and in one asking for clinician retrospective reports of their patients’ symptoms during the course of the pandemic .
Together, although these findings were overall mixed, it should be noted that three longitudinal studies that directly compared the course of individuals with contamination vs. other symptoms found a poorer course for contamination [5•, 9••, 11••], compared with one that did not find a difference (though this study was an outlier in terms of minimal overall worsening in patients with OCD) [12••]. Two studies specifically compared symptom domain scores across time, finding significantly worsened contamination, harm, and taboo-related symptoms during the pandemic [10••, 23], though direct comparisons of trajectories across symptom domains were not conducted.
Contamination symptoms in individuals with OCD were associated with increased COVID-19-related stress , COVID-related fear , new OCD symptoms focused on COVID-19 [9••], and COVID-19 dysfunctional beliefs (e.g., that the pandemic was caused by people being careless with hygiene, that fears/dangers about the world are confirmed) [21•].
Among 6041 individuals texting a support line in March, 2020, 60% endorsed obsession-like thoughts related to contamination and excessive washing, which were associated with increased distress levels [33,34]. Contamination symptoms were found to increase during the pandemic in college students , non-clinical adults [26•, 36]. One of these studies found that contamination-related OCD symptoms were similar to previously validated clinical samples and significantly greater than non-clinical samples across timepoints (April/May and again in July/August) [26•]. Finally, in one study of patients with ST-elevation myocardial infarction, contamination-related OCD symptoms were associated with significant delays in going to the hospital .
COVID-19-Centered Obsessive–Compulsive Symptoms
Studies investigated whether people began experiencing obsessions and compulsions with COVID-19 themes. A divide in frequency across samples recruited from clinic vs. online settings was again observed. In studies with online participants who self-identified with OCD, estimates of new, COVID-centered obsessions and compulsions were 35% in a youth sample (n = 37 ) and 58% in an adult sample (n = 252 ), for a pooled estimate of 55% (95% CI 47–58%). In contrast, rates of new COVID-19-centered obsessions and compulsions were generally lower in samples recruited from patients being treated in specialty clinics, including 4% (n = 113) , 5% (n = 240) [12••], and 15% (n = 65) . A study conducted in Italy was an exception to this pattern (n = 127), with 45% experiencing COVID-19-focused obsessions and compulsions early in the pandemic [9••]. Across these four studies, the pooled incidence of new COVID-19-focused symptoms among patients being followed in clinic was 16% (95% CI 13–20%).
Relatedly, COVID-19-stress syndrome has now been a widely studied construct, a cluster of stress responses to the pandemic including socio-economic consequences, traumatic stress, xenophobia, and most notably, danger/contamination fears and compulsive checking, which could be conceptualized as COVID-19-centered COVID-19 symptoms . Unsurprisingly, it appears that greater OCD severity, especially contamination and checking symptoms, are associated with all these COVID-19 stress symptoms, including contamination fears and excessive COVID-19-related checking . This study found that patients with OCD had greater stress across COVID-19 stress syndrome domains than patients with social anxiety disorder or specific phobias, and similar levels as those with panic and generalized anxiety disorders .
Non-clinical studies also showed the increased obsessive–compulsive symptom severity was associated with more intrusive thoughts and repetitive behaviors centered on COVID-19 [39,40], as well as COVID-19-related safety behaviors . Contamination symptoms specifically were also associated with COVID-19 safety behaviors . One of these studies adapted a standard OCD measure to assess COVID-specific concerns found that certain repetitive thoughts and behaviors were relatively prevalent in the general Chinese population, with 18% endorsing repetitively telling others to take precautions and 12% endorsing excessive news-checking.
Factors Associated With Obsessive–Compulsive Symptoms During the Pandemic
People with OCD have been found to have more pandemic-related fears [11••, 22] and stress , with COVID-19-related stress predicting a poorer longitudinal course of obsessive–compulsive symptoms in one study [10••]. Another study found that financial stress caused by the pandemic, pathological doubt, and being an adult (vs. a child), and being medically at risk for COVID-19 all corresponded with a poorer course of exposure and response prevention treatment . Greater pre-pandemic depression, OCD severity, and less social support all predicted greater exacerbations of OCD severity as well [9••]. In one of the only studies of youth with OCD during the pandemic, Tanir and colleagues found that attention toward COVID-19-related information, OCD duration, and knowing someone who had COVID-19 all predicted OCD exacerbations [11••].
Studies that compared individuals with OCD with healthy controls found that individuals with OCD experienced more internalizing symptoms, suicidal thoughts, sleep and appetite changes, fewer impulse control problems [9••], more COVID-related stress , and fear , as well as poorer coping strategies and less social support . One study compared mental health trajectories among individuals with psychiatric diagnoses, including OCD, with healthy controls . This study found greater increases in mental health symptoms in individuals without psychiatric diagnoses relative to people with more comorbid diagnoses (including OCD, anxiety disorders, and depressive disorders), though it is important to note individuals with OCD specifically were not evaluated nor were obsessive–compulsive symptoms as an outcome.
OCD severity during the pandemic has also been found to be directly correlated with suicidal ideation [9••, 17•, 44], poor coping [42,45–49], sleep disturbances [17•], family accommodation [17•], family conflict , avoidance , anxiety , depression , and medication adjustments [9••, 17•]. A greater number of OCD consults were seen in one emergency room psychiatry consult service during March, 2020, compared with March, 2019 .
In non-clinical samples, multiple studies showed that increased obsessive–compulsive symptoms were associated with increased adherence to guidelines [26•, 51], underscoring the potential adaptive role of obsessive–compulsive symptoms (e.g., washing, checking) in the presence of a true viral threat. In one of these studies, information-seeking in April/May, 2020 predicted increased OCD symptoms in July/August, 2020, which in turn predicted greater guideline adherence [26•]. That said, in a representative USA sample, COVID prevention behaviors were associated with having clinically elevated OCD symptoms, both broadly assessed and specific to contamination . Relatedly, COVID-19 media consumption was also associated with OCD in college student sample .
COVID-19-related fears were also associated with OCD severity in non-clinical samples [53,54]. Other factors associated with OCD included intolerance of uncertainty , being at risk for COVID-19 , emotional contagion , family conflict , loss of income , younger age [29,56], female gender [56,57], less psychological resilience , and psychiatric comorbidity .
A number of studies investigated whether healthcare workers experienced more obsessive–compulsive symptoms. Associations were found between healthcare worker status and compulsions , contamination symptoms , and overall OCD severity [57,61,62], though one did not find a difference in OCD severity .