Parkinson’s Disease vs. Essential Tremor: What’s the Difference?

Uncontrollable shaking, or tremor, is not unique to Parkinson’s disease. It’s one of several symptoms shared between the disease and essential tremor, a separate brain condition also responsible for unusual movements.

While neither condition has a cure, several treatments can help slow their progression. 

“With our team of specialists, we can help manage symptoms and help you feel more like yourself,” says Rees Cosgrove, MD, FRCSC, a Mass General Brigham neurosurgeon. “But the success of these treatments can depend on how soon a doctor makes a diagnosis.”

Dr. Cosgrove serves as director of Epilepsy and Functional Neurosurgery at Brigham and Women’s Hospital. He explains the differences between Parkinson’s disease and essential tremor, their symptoms, and existing treatment options.

What is the difference between Parkinson’s disease and essential tremor?

Essential tremor is much more common than Parkinson’s disease. According to the Parkinson’s Foundation, 1 million people in the United States live with Parkinson’s disease. Nearly 10 million have essential tremor.

Parkinson’s disease begins when nerve cells in the brain weaken, are damaged, or die. Many of these cells exist at the base of the brain in the substantia nigra, where they produce the chemical dopamine. The brain uses dopamine to initiate activity throughout the body.

When these nerve cells stop working and dopamine levels drop, the brain loses control over certain movements and functions.

Unlike Parkinson’s disease, doctors do not know what causes essential tremor. However, studies show mild changes occurring in the brains of patients with the condition. Damage appears in a part of the brain called the cerebellum, which is responsible for coordination.

What are the symptoms of Parkinson’s disease and essential tremor?

The symptoms of Parkinson’s disease and essential tremor are progressive, which means symptoms worsen over time.

Parkinson’s disease symptoms

Patients with Parkinson’s disease usually experience uncontrollable shaking when still. The shaking resembles a rhythmic, back-and-forth movement and increases under duress.

“It is an extremely frustrating condition to live with, causing both social and professional embarrassment,” says Dr. Cosgrove. “Interestingly, the shaking decreases when a patient intentionally moves their arms and legs.”

While shaking typically begins in the hands, it can also begin in the jaw or feet.

The other cardinal symptoms include:

• Slow movements (bradykinesia)

• Stiff arms, legs, or torso

• Problems walking, talking, and writing

• Problems with balance or posture, which can increase the risk of falling

In certain cases, the condition may also be associated with:

• Loss of smell

• Depression and anxiety

• Difficulty swallowing or chewing

• Loss of bladder or bowel control

• Dementia and memory problems

• Sexual dysfunction

• Hallucinations

• Fatigue and pain

• Muscle cramps, especially in the legs and toes

• Sudden drops in blood pressure, which can cause dizziness

Essential tremor symptoms

Those patients with essential tremor experience similar symptoms, but at opposite moments from Parkinson’s. Shaking begins when a patient tries moving their limbs. They’re unlikely to experience symptoms at rest.

“You may be eating, writing, or trying to get dressed when your hands start shaking uncontrollably,” says Dr. Cosgrove. “Then, as soon as you stop trying to move, the tremor goes away.”

Shaking can occur in the:

• Hands

• Arms

• Head

• Jaw

Your voice may sound shaky, too, without any other neurological signs. Lack of sleep or stress can worsen symptoms.

Risk factors of Parkinson’s disease and essential tremor

Men are more likely to develop Parkinson’s disease than women. The likelihood increases if:

• You are older than 60.

• You have close relatives with the condition.

• You have been exposed to certain pesticides.

• You have certain genes known to cause Parkinson’s disease.

Essential tremor can develop at any age, but it most often starts after age 40 or 50. According to the National Institutes of Health (NIH), essential tremor is an inherited disease in 50-70% of cases.

How is Parkinson’s disease diagnosed?

Specific tests do not exist for Parkinson’s disease, nor essential tremor.

Doctors with expertise in movement disorders rely on comprehensive neurological evaluations to rule out similar conditions. They ask patients about their symptoms and family history. They also use:

• Blood tests

• Computed tomography (CT) scan: Special x-rays produce cross-sectional images of the brain.

• Positron-emission tomography (PET) scans: A radioactive substance called a “tracer” helps measure brain function. It also helps identify suspicious activity that may signal a disease.

• Magnetic resonance imaging (MRI): A large magnet and radio waves examine organs and other structures inside the body.

• Skin biopsies

Conditions similar to Parkinson’s disease

Symptoms shared among other brain conditions make Parkinson’s disease even harder to diagnose.

These conditions, and their symptoms, include:

• Multiple system atrophy (MSA): Poor coordination and slurred speech, or both

• Lewy body dementia: Symptoms range from slow movements, rigid limbs, and shaking to memory loss, poor judgment, and confusion. Others include visual hallucinations and depression.

• Progressive supranuclear palsy (PSP): Difficulty controlling gait and balance, as well as an inability to move the eyes. Altered mood and behavior, including depression, apathy, and mild dementia, may occur, too.

• Corticobasal degeneration (CBD): Rigid limbs, impaired balance, and poor coordination. Symptoms may occur on one side of the body before affecting the other. Other symptoms can include shaking, hesitating or halted speech, difficulty swallowing, or the inability to move freely.

Treatment for trembling hands, feet, or other limbs

There is no known cure for Parkinson’s disease or essential tremor. Thankfully, there are several ways to treat and manage symptoms.

Parkinson’s tremor treatment