Have you noticed any physical changes recently, such as "my movements have become slower" or "my hands tremble when I'm at rest," but are you dismissing them as "just due to age"? These could be early signs of Parkinson's disease. Parkinson's disease is often mistaken for age-related decline, but if detected early and treated appropriately, it is possible to maintain a fulfilling life for as long as possible
table of contents
The four major motor symptoms of Parkinson's disease
Parkinson's disease is a disorder characterized by a decrease in dopamine nerve cells in the brain, resulting in four main motor symptoms: tremor, bradykinesia (slowness of movement), muscle rigidity, and postural instability (increased risk of falling). While it is more common in people over 50, there are also cases of early-onset Parkinson's disease that develop before the age of 40. The prevalence increases with age, and it is said to affect about 1 in 100 people (1,000 in 100,000) over the age of 65, but even across all age groups, it is not a rare disease, affecting about 100 to 180 people (1 to 1.8 in 1,000)
Characteristics of the four major motor symptoms
The four motor symptoms are as follows:
- Tremor: A typical example is resting tremor. The hands and feet shake when you are relaxed, sitting in a chair with your hands on your knees, or when you are walking. A characteristic feature is that the shaking stops (or becomes less) when you move your hands to pick something up
- Muscle rigidity (muscle stiffness): This is a condition where muscles become stiff and unable to move smoothly. Those with this condition often perceive it as shoulder stiffness or heaviness, while others may feel a jerky resistance (cogwheel rigidity) when trying to move the limbs or head
- Slowness of movement (bradykinesia/hypokinesis): Movements become generally slower, making fine motor skills such as dressing and undressing or turning over in bed difficult. "Freezing of gait," where the first step of walking is difficult, may also be observed
- Postural instability: This involves a decrease in the body's ability to maintain balance, making falls more likely. It often appears several years after the onset of the disease, but if this symptom is severe within two years of the onset, it may indicate a Parkinson's syndrome such as progressive supranuclear palsy
A characteristic of Parkinson's disease is that symptoms often do not appear simultaneously on both sides of the body, but rather begin on one side and gradually spread to the other side
Source: National Center for Intractable Diseases Information | Parkinson's Disease (Designated Intractable Disease 6)
Source: National Hospital Organization Tottori Medical Center | About the Symptoms of Parkinson's Disease
Non-motor symptoms that are surprisingly little known
In addition to problems with motor function, non-motor symptoms can appear even before motor symptoms develop. Typical symptoms include stubborn constipation, frequent urination, excessive sweating, fatigue, decreased sense of smell, and dizziness upon standing (orthostatic hypotension). Mental symptoms such as depression (a persistent feeling of unease) and apathy (a lack of interest in everything) may also occur
Which stage are you at? Explanation of the severity classification (Yahr classification)
The Hoehn-Yahr severity classification is widely used as an indicator of the progression of Parkinson's disease
[Hoehn-Yahr Severity Classification]
| severity | Symptoms |
|---|---|
| Ⅰ period | The symptoms are only on one side. Functional impairment is absent or minimal, and there is almost no disruption to daily life |
| II period | The impairment is bilateral, but there is no impairment in maintaining posture. There are some limitations in daily life and work |
| Ⅲ period | Postural reflexes are impaired, leading to a tendency to fall. Activities are somewhat limited, but employment is possible depending on the occupation. Functional impairment is mild to moderate, and independent living without assistance is possible |
| Ⅳth period | Standing and walking are possible with some assistance. However, there are severe functional impairments, making employment difficult. Partial assistance is required for daily activities |
| Stage V | Requires full assistance with daily activities. Confined to bed or wheelchair |
Currently, treatments have been developed, and with appropriate treatment, it is believed that the average life expectancy for people with Parkinson's disease is almost the same as that of the general population
Current treatments and future regenerative medicine
The basic treatment for Parkinson's disease is drug therapy to replenish the deficient dopamine, but long-term use presents challenges such as fluctuations in effectiveness. In recent years, research into regenerative medicine using iPS cells and other technologies has advanced rapidly, offering new hope
Standard treatment (drug therapy and rehabilitation)
The basic treatment involves drug therapy, such as L-dopa, to replenish the deficient dopamine. However, prolonged use can lead to problems such as the wearing-off phenomenon, where the drug's effects are shortened, and dyskinesia, where the body moves involuntarily against one's will. If diurnal variations in motor symptoms and dyskinesia become difficult to improve with drug therapy, surgical treatment may be considered. Exercise therapy, when used in conjunction with medication or surgery, can lead to further improvement
The guidelines recommend starting treatment as early as possible after diagnosis, as delays may lead to the disability becoming permanent
Source: Japanese Society of Neurology Guidelines | Parkinson's Disease Treatment Guidelines 2018 Part III Q&A on Parkinson's Disease Treatment "Chapter 4 Non-Pharmacological Therapy"
Source: Clinical Guidelines at a glance | Parkinson's Disease Treatment Guidelines 2018
A new option: regenerative medicine
For those whose medication is no longer effective or who wish to slow the progression of their disease, research into regenerative medicine is progressing as a new option. The root cause of Parkinson's disease is the loss of dopamine nerve cells in the brain. Therefore, treatment methods that replenish or repair the cells themselves are attracting attention
In April 2025, an announcement was made that clinical trials for "Parkinson's disease treatment using iPS cells," which had been conducted by the Center for iPS Cell Research and Application (CiRA) at Kyoto University and others, showed promising results in terms of safety and efficacy. The clinical trials had been conducted since 2018, and involved transplanting dopamine nerve cells created from iPS cells into the brain and observing the patients for two years
As a result, no serious side effects were observed, confirming its safety, and its effectiveness can also be estimated. Preparations are currently underway for manufacturing and sales approval in Japan
summary
Because Parkinson's disease is a progressive illness, early detection and treatment greatly impact one's quality of life (QOL). Instead of fearing it as an incurable disease, it's important to learn about drug therapy, rehabilitation, and regenerative medicine, and to approach it with a positive attitude