Parkinson's Disease

History

In 1817, a British doctor named James Parkinson wrote an important paper about an illness that eventually became known as Parkinson's disease. He observed that this illness made people have difficulty with their movements, and, experience trembling and stiffness in their bodies.

James Parkinson's careful study of individual cases and his insightful analysis of the disease's symptoms set the stage for later developments in this field of research. His work played a key role in establishing PD as a unique medical condition. Even though the exact cause of the disease wasn't known during his time, his thoughtful ideas encouraged more exploration into its underlying reasons.

James Parkinson's legacy to the field of neurology (A) The frontispiece to his essay on the Shaking Palsy, written in 1817
What causes PD symptoms?

The Role of Dopamine

Dopamine Depletion Hypothesis
In the 1960s, scientists made a big discovery: individuals with PD have less dopamine in their brains. This discovery led to the dopamine depletion hypothesis, which proposed that the shortage of dopamine could be a major factor contributing to PD.

What is Dopamine?
Dopamine is a messenger in the brain that helps control movement and mood. Dopamine levels significantly decrease in people with PD. This drop happens because certain brain cells that produce dopamine start to break down. These cells are important for sending signals that help keep movements smooth and coordinated. As dopamine levels drop, a series of effects cause the main symptoms of Parkinson's disease. Levodopa, which gets converted to dopamine in the brain, remains the cornerstone of treatment for motor symptoms in PD.

Going Beyond Dopamine
We now know that PD doesn't only affect dopamine but also many other neurotransmitters in the brain including serotonin, acetylcholine and norepinephrine. These other neurotransmitters can cause nonmotor symptoms (e.g., changes in mood, memory, and energy) that are also common in Parkinson's disease.

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Motor symptoms (e.g., tremor and stiffness) are easily seen and often used by doctors to recognize PD. However, non-motor symptoms can affect almost any body system and occur at any time during disease progression. Because these non-motor symptoms can’t be seen, they’re much more difficult to recognize as relating to PD and are much less identified in diagnosis. Therefore, it is very important to communicate with a doctor if you are experiencing these symptoms, especially if they are interfering with everyday life.

PD affects people in many different ways: physical, emotional, social, spiritual, and practical. Some people may experience feelings such as anger, anxiety, and depression. People may isolate themselves or feel the burden of social stigma. For others, PD may lead to hopelessness and a loss of identity, as well as create a financial burden and a general worry for the future. The total pain of PD can be felt in many different ways.

People caring for loved ones with PD also experience impacts on their well-being. Some care partners may feel burnout and stress from being responsible for another person’s health. Some may feel that their goals, independence, and everyday life is overshadowed, which may lead to a strained relationship with the person with PD. In other cases, the stress that care partners face may cause an inability to continue caring for their loved one because of a decline in their own health. It’s important that care partners also have access to resources to manage their own health.