Parkinson’s disease is a disorder of the nervous system that causes the breakdown of certain nerve cells in the brain. When the breakdown affects cells that produce the brain chemical dopamine, symptoms of Parkinson’s develop. Dopamine is a chemical that facilitates communication between the cells of the brain, helping them to function normally. Decreased levels of dopamine cause abnormal activity in the brain.
Parkinson’s disease is a progressive disorder, meaning that it gets worse over time. It causes both physical and cognitive symptoms, although the physical symptoms tend to be more familiar and better known.
According to the Mayo Clinic, physical symptoms of Parkinson’s disease typically involve impaired movement. This may be mild at first and therefore more difficult to recognize. Symptoms are typically more pronounced on one side than the other.
Unconscious movements, such as smiling, blinking or swinging one’s arms while walking, may decrease due to Parkinson’s. At the same time, people may develop uncontrollable shaking in one of the limbs called a tremor. Parkinson’s can cause the muscles to become more rigid. Movement can become slower and more labored, a symptom also known as bradykinesia.
Physical symptoms of Parkinson’s may be better known because they are observable by others. The abnormal activity in the brain caused by decreased dopamine can also cause cognitive symptoms, i.e., changes to the way one thinks. These are more difficult to observe.
Parkinson’s can cause memory deficits, slowed thinking, attention difficulties and loss of problem-solving ability. According to the Parkinson’s Foundation, cognitive symptoms of the disease can range in severity from mild cognitive impairment that has little effect on work or home life to more severely disruptive symptoms.