As Korea’s population ages, Parkinson’s disease is becoming more common, affecting approximately 1 percent of people 60 and older and 4 to 5 percent of those 80 and older. According to Professor Cho Jin-whan of the Department of Neurology at Samsung Medical Center, the disease is often misunderstood as solely a movement disorder, when in fact, motor symptoms are only the “tip of the iceberg.”
Professor Cho explains that dopamine, the neurotransmitter most affected by the disease, plays a role in emotional function, the brain’s reward system, and memory, which is why mood problems and cognitive issues are common in people with Parkinson’s. The disease’s progression varies widely, with some people living for 10 to 15 years after diagnosis with relatively little difficulty, while others may develop severe problems such as freezing of gait.
Understanding Parkinson’s Disease
A person can have no obvious symptoms even after losing more than half of their dopamine-producing cells, with the loss estimated to be around 60 to 70 percent by the time the first symptoms appear. The diagnosis of Parkinson’s disease is not always straightforward, as several disorders can resemble the disease at first, including multiple system atrophy, which can also involve cerebellar atrophy.
Professor Cho notes that a patient with multiple system atrophy may have that disease from the start, but it can look like Parkinson’s at the first visit, and the diagnosis becomes clearer as the patient is followed over time. The disease’s progression can be influenced by various factors, including genetics, with about 15 percent of cases having a genetic component, although a directly inherited form is rare, accounting for no more than 5 percent of cases.
Genetic testing can be helpful for patients with a family history or those who develop Parkinson’s at a young age, as it can help understand the disease’s characteristics and guide treatment. However, for patients diagnosed in middle age or later, or those without a family history, genetic testing may not be necessary, although some may still want to undergo testing to learn more about their prognosis or treatment options.
Early signs of Parkinson’s disease can include acting out dreams during REM sleep, a reduced or lost sense of smell, excessive sweating, dizziness on standing, and dry mouth, which can reflect changes in the autonomic nervous system. While these symptoms can have many causes, identifying Parkinson’s at this stage may offer little immediate benefit, and dopamine PET imaging can detect changes as early as five years before motor symptoms appear.
Diagnosis and Treatment
Professor Cho advises people to watch for a change on one side of the body, such as one arm swinging less than the other while walking, or movements on one side becoming smaller or slower, as these can be early signs of Parkinson’s. The diagnosis of Parkinson’s disease is typically made based on clinical symptoms, although dopamine positron emission tomography (PET) can assess how well the nerve endings involved in dopamine signaling are functioning.
Treatment options for Parkinson’s disease include levodopa, dopamine agonists, MAO-B inhibitors, and COMT inhibitors, which help slow the breakdown of dopamine or levodopa. The choice of drug depends on the patient’s symptoms and circumstances, and medication often works very well early on, although symptoms can become harder to control as the disease progresses.
Deep brain stimulation, which delivers electrical pulses through electrodes implanted in the brain, can be an effective treatment option for patients who respond well to medication but cannot sustain that benefit throughout the day. However, it is typically recommended for patients with severe tremor that medication cannot control, as it can be very effective in reducing tremor.
According to Professor Cho, the implanted electrodes in deep brain stimulation modify signaling in brain circuits affected by the loss of dopamine, although the stimulation itself does not increase dopamine production. The treatment can be tailored to the patient’s symptoms and circumstances, and it is generally recommended for patients who are likely to benefit from it.
As the disease progresses, patients may experience a range of symptoms, including motor symptoms, non-motor symptoms, and cognitive impairment. Professor Cho notes that maintaining good posture is important, as well as strengthening the weaker side of the body to restore balance. Speech and swallowing are essential for quality of life, and patients are encouraged to read aloud, articulate clearly, or sing loudly to keep the muscles involved in swallowing active.
Researchers are currently studying ways to stimulate or target the brain from outside the skull using ultrasound or magnetic fields, as well as stem cell and gene therapies, which may potentially change the treatment of Parkinson’s disease in the future. Through the Global Parkinson’s Genetics Program, researchers are analyzing genetic data from patients around the world using standardized methods, which may help predict how quickly someone’s disease will progress or how likely they are to experience side effects from a drug.
Professor Cho emphasizes that prompt treatment is essential in emergencies, such as sudden withdrawal from medication, which can trigger a severe reaction, including a sharp rise in blood pressure, loss of consciousness, and severe muscle rigidity. Pneumonia and falls are also common emergencies, and delays in treatment can make recovery more difficult.