Tremor Type

The nature of the tremor itself is one of the clearest ways to tell essential tremor and Parkinson’s disease apart.

A tremor is a specific type of shaking that affects a particular area (or areas) of the body. It is unintentional, meaning that the person experiencing the tremor is shaking without meaning to.

Resting vs. Action

A key difference between the tremors seen in essential tremor and Parkinson’s disease is when they occur: at rest or with movement.

People with essential tremor shake when they’re using a body part, a pattern doctors call an “action tremor.” People with Parkinson’s disease are more likely to shake when a body part is resting, known as a “resting tremor.”

Picture someone relaxing on a porch. If they have essential tremor, you might not notice anything until they reach for their glass — that’s when the shaking starts. If they have Parkinson’s disease, you’re more likely to see the tremor while their hand rests in their lap or on the arm of the chair.

This is the typical pattern, although it doesn’t apply to everyone all the time. In essential tremor, the shaking doesn’t always stop completely once the movement is finished, and some people with Parkinson’s disease have a tremor that shows up during movement instead of at rest.

Speed and Size

A few other clues can help tell the two tremors apart. Parkinson’s tremors tend to be slower and cover a wider range of motion than essential tremor. A hand tremor from Parkinson’s disease often starts at the wrist and ends with the fingers rubbing together, sometimes called a “pill-rolling tremor.”

Essential tremor tends to be faster and smaller, without that rolling motion. The tremor can also vary from person to person, which is why a neurologist will usually observe it during different activities and positions before making a diagnosis.

Additional Symptoms

In essential tremor, shaking is usually the main symptom a person notices. Parkinson’s disease involves tremor too, but a Parkinson’s diagnosis centers on another symptom called bradykinesia, or slowed movement, along with other signs. Not everyone with Parkinson’s disease has a tremor.

People with Parkinson’s disease often also develop muscle stiffness (rigidity), problems with balance and coordination, a stooped posture, and a shuffling walk. Furthermore, they frequently notice changes that have nothing to do with movement, like sleep problems or changes in mood, which essential tremor doesn’t typically cause.

The Diagnostic Process

Neurologists, doctors who specialize in the brain and nervous system, diagnose both essential tremor and Parkinson’s disease. Diagnosis for both conditions is still mainly clinical, based on a person’s symptoms, a physical exam, and their medical history, including any family history of tremor or related conditions.

There’s no single test that can confirm essential tremor or Parkinson’s disease on its own, but imaging can sometimes help when the diagnosis isn’t clear from a neurological exam alone.

One option is a brain scan called a DaTscan, which is approved by the U.S. Food and Drug Administration (FDA) to help doctors tell essential tremor apart from tremor caused by Parkinson’s disease.

A DaTscan measures dopamine activity in the brain, and people with Parkinson’s disease usually show reduced activity. Because a DaTscan involves radiation exposure and isn’t available everywhere, it’s generally reserved for cases where the exam alone doesn’t give a clear answer.