Identifying Markers of Disease Subtypes and Disease Progression in the Syndrome of Essential Tremor

The goal of this observational study is to learn about epidemiology, biologic markers, disease subtypes and possible prognostic factors in essential tremor (ET) patients. The main question\[s\] it aims to answer are: * The prevalence of ET-plus compared to ET in a prospectively collected ET population. * To assess in detail the heterogenous group of ET patients using comprehensive clinical (motor and non-motor scales, questionnaires), imaging \[magnetic resonance imaging (MRI), sonography of substantia nigra and cerebral vessels\], neurophysiological (tremor analysis, digital spiral drawing) and laboratory markers (sGFAP, sNfL, routine laboratory parameters). * To assess possible non-invasive markers of neurodegeneration in ET patients (optic coherence tomography, alpha-synuclein in olfactory mucosa) Participants will be asked to undergo the above mention evaluation at baseline and at follow-up approx. 5 years later. Researchers will compare the findings within the ET group to independently existing cohorts of healthy controls and/or patients with other movement disorders like Parkinson's disease.