claim: Parkinson's disease causes tremors.
evidence: A tremor -LSB- ˈtrEm @r -RSB- is an involuntary , somewhat rhythmic , muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts .. muscle contraction. muscle contraction. oscillations. neural oscillations. It is the most common of all involuntary movements and can affect the hands , arms , eyes , face , head , vocal folds , trunk , and legs .. vocal folds. vocal folds. Most tremors occur in the hands .. In some people , a tremor is a symptom of another neurological disorder .. neurological. neurology. A very common tremor is the teeth chattering , usually induced by cold temperatures or by fear .