Dopamine plays an important role in neural functioning. When something happens that significantly alters its levels, the changes are noticeable. One such example is Parkinson's disease, in which the brain cells that make dopamine become destroyed. The destruction of the cells leads to a drop in dopamine in the brain. As a result, patients have movement problems, such as a shuffling gait. Parkinson's disease also causes symptoms such as tremors, slowed movements, loss of fine hand movements, stooped position, lack of facial expression and muscle aches. MedlinePlus explains that Parkinson's disease starts after age 50 and affects women and men.
But what causes Parkinson's disease? The MayoClinic.com points out that the specific cause of Parkinson's disease is not known, but different theories exist. For example, environmental triggers, such as toxin exposure, or gene mutations, may cause Parkinson's disease. A study funded partly by the National Institute of Neurological Disorders and Stroke suggests that an immune system gene may contribute to the onset of Parkinson's disease.
The gene that this research looked at is located in the human leukocyte antigen (HLA) region. The Merck Manual Professional Edition notes that the human leukocyte antigen region “encodes cell surface molecules specialized to present antigenic peptide to the T-cell receptor (TCR) on T cells.” Reuters Health reports that the study included 2,000 people with Parkinson's disease and 2,000 healthy controls from Georgia, New York, Oregon and Pennsylvania. The researchers found a strong link between the genes in the human leukocyte antigen region and Parkinson's disease; however, they are not sure which specific gene is linked to the neurological disorder, as numerous genes are in that region.
So what does this study mean? As Reuters Health points out, autoimmune responses, infections or inflammation may contribute to the disease's onset. If researchers identify the specific gene in the human leukocyte antigen region and how it affects the development of Parkinson's disease, it may lead to new treatment options for the disorder. The current available treatments for Parkinson's disease help control the symptoms of the disorder, but do not cure it. For example, the MayoClinic.com notes that the drug levadopa is the most effective medication for Parkinson's disease, which is often combined with carbidopa to prevent the levadopa from converting to dopamine before it crosses the blood-brain barrier. However, once the disease progresses, levadopa does not provide as much relief as it did before.