Increased Prevalence of Non-motor Symptoms in Essential Tremor

Cases with essential tremor (ET) have been described with Lewy body inclusions, the hallmark of Parkinson disease (PD). Patients with PD may suffer from anosmia, depression, constipation, and rapid eye movement sleep behavior disorder (RBD), sometimes years before the appearance of their motor syndrome. The objective of this study was to evaluate the prevalence of these non-motor Parkinson's associated symptoms in patients with ET.

Fifty ET subjects were contacted by phone and given questionnaires evaluating the presence or absence of anosmia, depression, constipation, and RBD. Frequencies of these symptoms were compared with their published prevalence in the general population.

Of the patients with ET, 4.5% reported having anosmia or hyposmia and 21.7% reported being constipated, similar to what is observed in the general population. Using a screening questionnaire for RBD, 43.5% of ET patients are possibly suffering from RBD, whereas in the general population prevalence is estimated to be 0.5%. Finally, depression was detected in 21.7% of ET patients; in the general population, prevalence is 5%.

Patients with ET seem to have more RBD and more depression than found in the general population. Prospective studies with normal control groups are needed to confirm these findings.