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: Earlier age at 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.