Parkinson’s disease: symptoms, causes, diagnosis, treatment

TL;DR:

Parkinson’s is a progressive brain disorder that affects movement.
Early clues include tremor, slowness, stiffness, and sleep or smell changes.
Diagnosis is clinical, with DaTscan used in select cases.
Levodopa is the mainstay, with add-on drugs and devices for later stages.
Exercise and smart daily habits improve function and quality of life.

What is Parkinson’s disease

Parkinson’s disease is a brain disorder that causes movement problems and many non-movement symptoms. It happens when cells that make dopamine in a small brain area called the substantia nigra stop working or die. Loss of dopamine leads to tremor, slowness, stiffness, and balance trouble. Scientists do not yet have a cure. Treatments can ease symptoms and help people live well.

How common is it

Parkinson’s is one of the most common neurological diseases worldwide. The World Health Organization estimates that more than 8.5 million people were living with Parkinson’s in 2019, roughly double the number 25 years earlier. Deaths and disability from Parkinson’s also rose sharply over that period.

In the United States, about 90,000 people are diagnosed each year, with more than a million living with the disease. Global totals are projected to rise through 2050 as populations age.

Core symptoms

Motor symptoms

Resting tremor, often starting on one side.
Slowness of movement that makes tasks take longer.
Stiffness that limits arm swing and turns.
Balance and walking changes, including shuffling steps.

Non-motor symptoms

Reduced sense of smell.
Constipation and urinary changes.
Mood and sleep problems, including acting out dreams.
Thinking changes, fatigue, pain, and low blood pressure on standing.

Not everyone has the same mix. Symptoms change over time and vary in speed and pattern. Regular exercise can improve many symptoms.

What causes Parkinson’s

Most cases are “idiopathic,” meaning no single known cause. A mix of age, genes, and environmental factors likely drives risk. A small share of people carry genetic variants that raise risk. Pesticide exposure and head injury have links to higher risk in studies. The biology centers on loss of dopamine-making neurons and buildup of alpha-synuclein protein in the brain.

Diet patterns are being studied. Research suggests a Mediterranean-style diet and higher flavonoid intake may be linked to lower risk, but evidence is still emerging.

How doctors diagnose it

Diagnosis is clinical. A neurologist reviews history, medicines, family risk, and checks movement. There is no single blood test. Doctors may order brain imaging if the story is unclear or to rule out another cause.

A DaTscan is a nuclear medicine test that shows dopamine transporter activity. It helps separate Parkinsonian syndromes from essential tremor or drug-induced symptoms. It is not needed for every patient and cannot tell the exact type of Parkinsonism by itself.

Common tests during workup

Medication review to rule out drug-induced parkinsonism.
Blood tests to exclude look-alike conditions.
MRI if atypical signs exist.
DaTscan in select cases when the diagnosis is uncertain.

Stages and progression

Doctors often describe early, mid, and advanced stages based on symptoms and response to treatment. Many people do well for years with medicine, exercise, and therapy. Later on, motor fluctuations and dyskinesias can appear as doses wear off. Falls, swallowing trouble, and thinking changes may add complexity. Care plans should change as needs change.

Treatment overview

There is no cure yet, but treatment can be very effective. Plans are tailored to goals, age, work and family needs, side-effect risk, and other conditions.

Medications

Carbidopa/levodopa. The first-line choice for most people. It reduces slowness and stiffness and often helps tremor. Over time, “off” periods or dyskinesia may occur and can be managed with dose timing, long-acting forms, or add-on drugs.
Dopamine agonists and MAO-B or COMT inhibitors can smooth response or reduce “off” time. Choice depends on age and side-effect profile.
Apomorphine rescue or continuous infusion can reduce “off” episodes in advanced disease. The FDA approved a new apomorphine drug-device system in 2025 that delivers continuous subcutaneous dosing.
24-hour levodopa infusion. In 2024 the FDA approved a continuous subcutaneous levodopa-based infusion for adults with advanced Parkinson’s, offering steadier control for some patients.

Levodopa remains the most effective symptomatic medicine in Parkinson’s care. It treats symptoms but does not stop disease progression.

Device and surgical options

Deep brain stimulation (DBS). Implanted electrodes deliver targeted pulses to brain circuits, improving motor fluctuations and tremor for many people who respond to levodopa but have disabling “off” time or dyskinesia. Technique and hardware continue to advance, including adaptive systems that adjust stimulation in real time. Risks include infection, bleeding, mood or speech changes, and device issues.
Focused ultrasound. For select patients with tremor or dyskinesia, ultrasound can create precise lesions without an incision. In 2025 the FDA cleared bilateral focused ultrasound for appropriate advanced Parkinson’s cases in the United States.

Rehabilitation and lifestyle

Exercise. Aim for at least 150 minutes per week. High-intensity aerobic work, cycling, or fast treadmill walking show the best data for slowing symptom progression or stabilizing function. Balance and strength training reduce falls. Start early and make it social.
Speech and swallowing therapy. Programs like LSVT LOUD improve voice volume and clarity.
Occupational therapy. Adapts home and work tasks to keep independence.
Nutrition. A plant-forward, fiber-rich diet supports bowel function and overall health. Time protein away from levodopa if absorption is an issue. Consider Mediterranean-style patterns if culturally suitable.
Sleep care. Treat sleep apnea, REM sleep behavior disorder, and insomnia to improve daytime function.
Mental health. Depression, anxiety, and apathy are common and treatable. Counseling and support groups help.

Living day to day

Small changes reduce risk and save energy.

Medication timing. Take levodopa on schedule, usually apart from high-protein meals when needed. Use a smartphone alarm or pill organizer.

Fall prevention. Clear clutter, add grab bars, improve lighting, and use sturdy footwear. Freezing at doorways can improve with cueing, such as floor stripes or a rhythmic metronome.

Driving and work. Reassess as needed. Occupational therapists can advise on adaptive tools and job changes.

Care partners. Learn the signs of “off” periods and dyskinesia. Share calendars and medication logs.

Red flags that need urgent care

Sudden confusion, fever, or severe swallowing trouble.
Falls with possible head injury.
Rapidly worsening hallucinations or delusions.
Extreme sleepiness soon after a new drug.
Call your clinician or emergency services as local practice advises.

What happens next in research

Research is moving on biomarkers, genetics, and brain-circuit therapies. Scientists are testing blood and spinal fluid markers and skin biopsies to detect disease earlier. Trials are also exploring gene and cell therapies, immune pathways, and adaptive brain stimulation that changes settings based on symptoms or brain signals. Global forecasts show Parkinson’s numbers will rise through 2050, which raises the stakes for prevention and better care.

Quick care checklist

Use this list at clinic visits.

Bring an updated medication list with doses and times.
Track “on” and “off” periods for one week before the visit.
List top three goals, such as walking farther or sleeping better.
Ask about exercise targets and a referral to PT, OT, and speech therapy.
Review fall risks at home and driving safety.
Discuss mood, sleep, constipation, and pain.
Ask if you qualify for infusion therapy, focused ultrasound, or DBS.
Set a follow-up plan and how to reach the team between visits.

Why it matters

Parkinson’s affects daily life at home, work, and in the community. Early diagnosis, regular exercise, and the right mix of medicines and devices can keep people active for many years. A clear plan also reduces caregiver strain and helps families adapt as needs change.

Sources: