Parkinson’s disease is a progressive movement disorder that affects nearly one million people in the United States and more than six million worldwide, changing how the brain controls movement and bringing challenges that extend far beyond trembling hands.

Understanding the Numbers: Who Gets Parkinson’s Disease

Parkinson’s disease ranks as the second most common age-related brain condition that causes parts of the brain to break down over time. This condition affects at least one percent of all people over the age of 60 around the world, making it a significant health concern for aging populations everywhere.^[3]

Most people begin showing symptoms of Parkinson’s disease after they turn 50 years old, with the average age of diagnosis being around 60. However, the disease can appear earlier in some cases. About five to ten percent of those diagnosed experience what doctors call early-onset Parkinson’s, which begins before age 50. In rare instances, adults as young as 20 can develop the condition, though this is extremely uncommon and often involves a family history of the disease.^[10]

Men face a slightly higher risk of developing Parkinson’s disease compared to women, though scientists have not fully explained why this difference exists.^[3][6]

What Triggers Parkinson’s Disease

The exact reasons why some people develop Parkinson’s disease remain unclear, which can be frustrating for newly diagnosed patients and their families. Scientists believe the condition results from a complex interaction between a person’s genes and the environment around them, rather than a single identifiable cause.^[5]

The disease begins when nerve cells in a small but crucial part of the brain called the substantia nigra start to weaken, become damaged, or die. The substantia nigra is a production center for dopamine, which is a chemical messenger that plays a vital role in controlling how the body moves. When these nerve cells stop working properly, dopamine levels drop dramatically, leading to the movement problems that are the hallmark of Parkinson’s disease.^[1]

While most cases happen for reasons that remain unknown, researchers have identified some contributing factors. A person’s advancing age is the clearest risk factor. Some individuals carry genetic changes that increase their susceptibility, especially those with a family history of the disease. Environmental exposures, such as contact with certain pesticides, air pollution, or industrial solvents, may also play a role in triggering the condition.^[7]

By the time symptoms become noticeable, a person has typically already lost between 60 and 80 percent of the dopamine-producing cells in the substantia nigra. This means the disease process has been quietly unfolding in the brain for months or even years before the first tremor or stiffness appears.^[1]

Who Faces Greater Risk

Certain groups of people face a higher likelihood of developing Parkinson’s disease based on factors they cannot always control. Age stands out as the most significant risk factor, with the disease becoming more common as people enter their 60s and beyond.^[3]

Having a close family member with Parkinson’s disease increases risk, though most people with the condition do not pass it to their children. Researchers have identified specific gene mutations that raise susceptibility, particularly in cases where the disease appears before age 40. However, carrying these genetic changes does not guarantee someone will develop Parkinson’s.^[5]

People who work with or live near certain chemicals face elevated risk. Exposure to pesticides used in agriculture, particular industrial solvents, and areas with heavy air pollution have all been linked to higher rates of Parkinson’s disease. These environmental factors appear to interact with genetic susceptibility in ways scientists are still working to understand.^[7]

Men develop Parkinson’s disease slightly more often than women, though both sexes can be affected at any age. The reasons behind this gender difference remain under investigation.^[6]

Recognizing the Signs and Symptoms

Parkinson’s disease announces itself differently in each person, making it challenging to identify early on. The symptoms typically begin so gradually and mildly that people often dismiss them as normal signs of aging. The condition usually starts affecting one side of the body first, then eventually spreads to both sides, though symptoms often remain worse on the side where they began.^[2]

The most recognizable symptom is tremor, which is a rhythmic shaking that usually starts in the hand or fingers while the muscles are at rest. This resting tremor often causes people to rub their thumb and forefinger together in what looks like rolling a pill between the fingers. The shaking typically lessens when a person uses the affected hand to perform a task. About 80 percent of people with Parkinson’s experience tremor, though some never develop this symptom.^[1]

Slowed movement, called bradykinesia, is another primary feature that must be present for a Parkinson’s diagnosis. People describe feeling as though their muscles have become weak, though the problem actually lies in how the brain controls those muscles rather than any true loss of strength. Simple tasks like buttoning a shirt or getting out of a chair become increasingly difficult and time-consuming.^[3]

Muscle stiffness or rigidity can affect any part of the body, making movements feel tight and restricted. This stiffness can be painful and may limit the normal range of motion in joints. People often notice their arms no longer swing naturally when they walk, or that their posture becomes stooped.^[2]

Balance problems and difficulty with coordination develop as the disease progresses, increasing the risk of falls. People may notice they take smaller, shuffling steps or sometimes experience “freezing,” where their feet seem stuck to the floor and they temporarily cannot move forward.^[16]

Changes in facial expression occur when the facial muscles become rigid, causing people to show less emotion in their features even when they feel happy or engaged. Speech often becomes softer, slower, or more monotone. Handwriting typically shrinks and becomes cramped and difficult to read.^[1]

The range of non-movement symptoms extends widely. Many people experience sleep disturbances, including acting out their dreams during sleep or excessive daytime sleepiness. Mental health changes such as depression and anxiety affect the majority of patients at some point. Cognitive problems may develop, and many people eventually experience dementia as the disease advances. Constipation, excessive saliva production, difficulty swallowing, decreased sense of smell, low blood pressure when standing, and sexual dysfunction all occur frequently.^[6][9]

Protecting Yourself: Prevention Strategies

Because scientists have not identified a single clear cause of Parkinson’s disease, proven prevention strategies remain limited. However, some lifestyle choices and habits may help lower risk or support overall brain health, even though they cannot guarantee the disease will not develop.^[3]

Regular physical exercise appears to offer potential protective benefits for the brain. Some early research suggests that staying physically active throughout life may help reduce the risk of developing Parkinson’s or slow its progression if it does occur. Exercise supports healthy brain function, improves cardiovascular health, and may help protect the nerve cells that produce dopamine.^[17]

Avoiding or limiting exposure to environmental toxins makes sense based on what researchers know about risk factors. When possible, reducing contact with pesticides, industrial chemicals, and areas with significant air pollution may help lower risk, though more research is needed to understand these connections fully.^[7]

Maintaining a healthy diet rich in fruits, vegetables, whole grains, and healthy fats supports overall brain health. While no specific diet has been proven to prevent Parkinson’s disease, eating well provides the nutrients the brain needs to function optimally and may support the health of nerve cells.^[4]

For people with a strong family history of Parkinson’s disease, genetic counseling may provide information about their personal risk. However, carrying genes associated with Parkinson’s does not mean the disease will definitely develop, and most people with Parkinson’s do not have a family history of the condition.^[5]

How the Disease Changes the Body

Understanding what happens inside the brain during Parkinson’s disease helps explain why symptoms develop and worsen over time. The disease primarily damages a region deep in the brain called the basal ganglia, which acts as a control center for movement, coordination, and other important functions.^[3]

Within the basal ganglia sits the substantia nigra, a small paired structure that produces dopamine. This chemical messenger is essential for sending signals between nerve cells that control movement. Under normal circumstances, when the brain sends commands to move a muscle, dopamine helps fine-tune those movements, making them smooth and purposeful. When dopamine levels drop due to dying nerve cells, movements become slow, stiff, and difficult to control.^[1]

People with Parkinson’s disease also lose nerve endings that produce norepinephrine, another important chemical messenger. Norepinephrine helps control automatic body functions that people do not consciously think about, such as heart rate, blood pressure, digestion, and bladder function. The loss of norepinephrine explains why many people with Parkinson’s experience fatigue, blood pressure changes when standing up, digestive problems, and other symptoms unrelated to movement.^[10]

Inside the damaged brain cells of people with Parkinson’s, scientists find unusual deposits called Lewy bodies. These deposits consist mainly of clumps of a protein called alpha-synuclein. Researchers do not yet fully understand why these protein clumps form or exactly how they contribute to cell death. Some evidence suggests that the cell’s normal system for breaking down and disposing of damaged proteins fails, allowing harmful protein clumps to build up to toxic levels that eventually kill the cell.^[1]

The disease progresses gradually, with symptoms typically worsening over many years. As more nerve cells die and dopamine levels continue to decline, symptoms become more severe and begin affecting both sides of the body. Eventually, the deterioration may spread to other brain regions, affecting memory, thinking ability, and emotional regulation. This explains why many people develop cognitive problems and dementia in later stages of the disease.^[3]

The rate at which Parkinson’s disease progresses varies dramatically from one person to another. Some individuals experience only mild symptoms that worsen very slowly over decades, allowing them to maintain good quality of life for many years. Others face more rapid progression with symptoms that become severe within a shorter timeframe. Unfortunately, doctors cannot predict at diagnosis how quickly the disease will advance in any particular person.^[5]