Essential Tremor Can Affect Anyone at Any Age 

I've read that ET usually affects the whole hand in general -- not one or two fingers. So, what about the quivering of a finger when held up against gravity (postural tremor)? Would that tend to indicate task-specific tremor, which is a different condition? My index finger has developed a quiver when held up while playing piano, or when holding it up from the computer mouse. My finger also quivers if I slowly curl it up (action tremor). Stress can also exacerbate tremor conditions. Fortunately, it doesn't quiver in the resting state, such as while resting on the mouse or while hanging my hand down by my side. That would suggest Parkinson's.