The role of aging in the clinical expression of essential tremor.

Essential tremor is the most common form of abnormal tremor. It is a monosymptomatic disorder characterized by action tremor but no other sign of motor dysfunction. More than half of all cases are inherited through a Mendelian dominant gene. Mild essential tremor is probably the cause of tremulousness that is frequently attributed to aging. The prevalence of essential tremor increases with age, and aging appears to have an independent effect on the clinical characteristics of essential tremor. Autopsies have revealed no discernible pathology. Essential tremor probably emerges from subtle pathologic transformation of a physiologic neuronal oscillator, possibly the inferior olive. A more complete characterization of the effects of aging on motor pathways may be necessary to fully understand the natural history and pathogenesis of this disorder.