Parkinson’s disease is a progressive neurological disease that affects movements, such as walking and writing. Around four million people have Parkinson’s disease. It is usually seen in people over the age of 50, but people under the age of 40 can also develop the disease.
Symptoms of Parkinson’s disease start to appear when certain nerve cells lose their ability to produce the chemical messenger or ‘neurotransmitter’ dopamine and dopamine no longer transmits nerve impulses from cell to cell. As a result there are changes in a person’s movements, such as walking and writing.
The reason why these dopamine-producing brain cells stop working is still unknown. Scientists think that certain people may have an inherited susceptibility to develop Parkinson’s disease. Environmental factors may also be a possible cause, but researchers have been unable to fully confirm this yet. The symptoms of Parkinson’s disease only start to appear after a major proportion of the dopamine-producing cells in the part of the brain known as the substantia nigra have stopped working. The disease is diagnosed by a neurologist on the basis of a clinical examination and the patient’s history of symptoms.
The symptoms of Parkinson’s disease start in stages and develop slowly, and are not all the same for everyone. The main symptoms are tremor, muscle stiffness and slowed movement. Resting tremor is the most obvious symptom of Parkinson’s disease, affecting almost 70% of patients. It usually starts to affect one hand or arm. It typically occurs when that part of the body is resting, and lessens or even disappears when the affected part is being used. Another common symptom is muscular stiffness, which can affect many daily activities. Due to muscular stiffness, people with Parkinson’s disease might find it difficult to turn around when walking, get out of a chair or turn over in bed. It can also be difficult to perform tasks that require fine finger movements, such as writing, unlocking a door with a key or sorting through loose change when shopping.
Movements also become gradually slower and the range of movement will become narrower. These symptoms are considered to be the most disabling. People who have been suffering from Parkinson’s disease for many years will often walk with short steps, and their feet may barely leave the ground. They may have a stooped posture, small handwriting and reduced degree of facial expressions. Balance is often impaired, the sense of smell weakened and they may have a monotonous and hoarse voice. In the later stages of the disease, patients may also suffer from ‘freezing’, which means a momentary inability to move one’s feet when walking, and feels like the feet are glued to the floor.
Even though Parkinson’s disease primarily affects movements, the disease also includes other types of symptoms. These symptoms include sleeping problems, considerable tiredness during the day, depression, dysfunction of the autonomic nervous system (the nervous system that regulates the functions of the internal organs), constipation and frequent need to urinate during the night, which results in broken sleep. These ‘non-motor symptoms’ are mild during the early stages of the disease and may not cause significant problems, but as the disease progresses they will have a greater effect on daily life.
While there is currently no cure for Parkinson’s disease, there is a wide range of treatments that effectively alleviate the symptoms. Research into new forms of treatment also provides patients with hope. Researchers are working on opportunities offered by cell and tissue transplantation and gene therapy. Researchers are also trying to develop forms of treatment that aim to protect the dopamine-producing cells in the brain from being destroyed.
Current treatment methods are based on the knowledge that people suffering from Parkinson’s disease have a lower than normal level of dopamine in their brains. Treatment methods are categorised into two main groups based on whether the medication replenishes the levels of dopamine in the brain or mimics the action of dopamine.
Dopamine levels can be replenished with various medicines based on levodopa, which is converted into dopamine in the brain, or with medicines called MAO-B (monoamine oxidase B) inhibitors which prevent dopamine from breaking down in the brain. Other medicines called dopamine agonists can mimic the action of dopamine.
