Clinical features	Parkinson's disease	Essential tremor
Age at onset	> 50 years	Bimodal: teens and 50s
Gender	Men more than women	Men and women equal
Family history	> 25 percent	> 90 percent
Asymmetry	Affects ipsilateral limbs at first	Often symmetric
Character	At rest	Postural, kinetic
Frequency	4 to 6 Hz	4 to 10 Hz
Distribution	Hands, legs	Hands, head, voice
Effect of alcohol on tremor	Unaffected	Reduced by alcohol
Associated findings	Bradykinesia, rigidity, postural instability	—