Earlier age at onset is associated with more severe sensory phenomena in drug-naive, comorbidity-free patients with obsessive-compulsive disorder

Introduction: Sensory phenomena (SP) are subjective experiences, such as feelings of discomfort or incompleteness, which often precede repetitive behaviors in patients with obsessive-compulsive disorder (OCD). Although previous studies have shown that SP are common in early-onset OCD, the relationship between age at onset and SP severity remains unclear. Methods: This cross-sectional study included 30 drug-naive patients with OCD, without comorbid psychiatric or medical/neurological disorders, and with at least one lifetime SP. SP severity was assessed using the University of São Paulo Sensory Phenomena Scale (USPSPS). Multiple regression analysis was conducted to examine the association between age at onset and SP severity, controlling for sex, autistic traits, and obsessive-compulsive symptom severity. Sensitivity analyses evaluated illness duration and anxiety and used a two-part analysis to address the floor at USPSPS = 0. Robustness was assessed using bias-corrected (BC) bootstrap 95% confidence intervals and influence diagnostics. Results: = 0.007; BC bootstrap 95% CI -0.300 to -0.064). Sensitivity analyses, including models additionally adjusting for illness duration or anxiety, and influence diagnostics, supported the robustness of this association. In a two-part analysis, autistic traits were associated with the presence of current SP, whereas earlier onset was associated with greater SP severity. Discussion: Earlier onset of OCD was associated with more severe SP after adjustment for clinical covariates. These findings may be consistent with a neurodevelopmental contribution to SP severity in OCD. Further longitudinal and qualitative studies on SP are warranted.