The trembling is usually temporary and disappears when the underlying condition is corrected. This almost excludes PD as a cause of the trembling. However, within two years other PD symptoms appear. The trembling in ET has a different relationship to the electrical activity of the involved muscles than the trembling in PD or the trembling in physiological tremor. Physiological trembling refers to the intrinsic or inherent trembling present in all of us, the trembling which manifests itself during anxiety and stress.
Physiological tremor has a different relationship to muscular activation.
Response to drugs. The trembling of ET may be temporarily suppressed by alcohol. The prevalence of ET increases with age. A study that surveys people in a retirement community will come to a different conclusion than one that surveys people in a college town. For every 10 PD patients who see a movement disorder specialist, one ET patient sees a movement disorder specialist.