A variety of causes and conditions can cause Parkinson's-like symptoms, such as:

 Drugs and Medications

 Age

 Other Causes

Each of these are briefly discussed further below.

Drugs and Medications

If some drugs and medications are used for long periods of time, or in excessive doses, then they can cause some symptoms which are similar to Parkinson's Disease. For example:
 Medications used to treat psychiatric disorders, such as haloperidol (Haldol) and chlorpromazine (Thorazine), can cause similar symptoms to Parkinson’s.

 Drugs used to treat nausea, such as metoclopramide (Reglan) and prochlorperazine (Compazine), can also cause similar symptoms to Parkinson’s.

 The epilepsy drug valproate (Depacon) may also cause similar symptoms to Parkinson’s, such as severe tremors.

The problems and side-effects caused by these drugs are reversible and they usually disappear completely a few weeks or months after you stop taking them.

Age

Old age can cause some mild, Parkinson's-like symptoms. For example, a slow, unsteady walk, trembling, and slight trouble with speaking or writing.

Other Causes

Parkinson’s-like symptoms can also be caused by a range of other conditions. For example, a common type of tremor, known as essential tremor, isn't caused by Parkinson's. Stiffness can be caused by arthritis. A stooped posture may be caused by age or osteoporosis.