Abstract / Description
Abstract Background Olfactory dysfunction is a recognized non-motor feature of Parkinson’s disease (PD) and has also been described in essential tremor (ET). However, olfaction in essential tremor with rest tremor (ET + RT), a recently defined subtype, remains insufficiently explored. Objectives To assess olfactory function in patients with ET + RT and to compare their olfactory performance with those of patients with PD, ET, and healthy controls. Methods This cross-sectional study included 125 participants: 71 with tremor-dominant PD, 16 with ET, 16 with ET + RT, and 22 age- and sex-matched healthy controls. PD severity was assessed using the Hoehn and Yahr scale and the Unified Parkinson’s Disease Rating Scale (UPDRS). Tremor severity in ET was evaluated with the Fahn–Tolosa–Marin Tremor Rating Scale, while ET + RT patients were assessed using UPDRS Part III due to rest tremor. Olfactory function was evaluated using the Connecticut Chemosensory Clinical Research Center test. Results Median olfactory scores were lowest in the PD group, followed by ET + RT, ET, and controls. PD patients had significantly lower scores than ET patients and healthy controls. ET + RT patients had significantly lower scores than controls. No statistically significant differences were observed between PD and ET + RT or between ET and ET + RT. Conclusion ET + RT patients demonstrated numerically lower olfactory scores than patients with isolated ET, although the difference was not statistically significant. Olfactory scores in ET + RT were intermediate between ET and PD. Given the cross-sectional design, limited sample size, and absence of dopaminergic imaging, these findings should be interpreted cautiously and do not allow conclusions regarding longitudinal disease progression.