Pathological Findings of Parkinson's Disease

Parkinson's disease, reports MayoClinic.com, is a degenerative nervous system disorder that affects movement. A minor tremor may gradually escalate to problems with balance, coordination, swallowing and talking. Symptoms include bradykinesia, or slowness of movement; rigidity; problems with posture; loss of automatic movements such as blinking and smiling; akinesia, the freezing of movement; and dementia. There is no cure but medications and treatment may help to alleviate symptoms.

Dopamine and the Substantia Nigra

• Parkinson's disease occurs when nerve cells in the part of the brain called the substantia nigra begin to die off, according to Brown University's Division of Biology and Medicine (Brown Biomed). These nerve cells produce dopamine, a neurotransmitter that regulates movement and emotions, the National Parkinson Foundation reports. When over 80 percent of these nerve cells die, symptoms of Parkinson's begin to appear. Why these nerve cells die is not entirely known; however, there are several theories.

Free Radicals

• Free radicals, unstable molecules generated through normal metabolism, may be a contributing factor to nerve cell death, according to Brown Biomed. Free radicals, especially those derived from metals, try to gain stability through oxidation of nearby molecules, causing damage. Parkinson's patients tend to have higher iron levels in the substantia nigra, and lower levels of ferritin, a protein that helps to isolate iron from oxidation. If free radicals are indeed a cause, antioxidants may be a preventive measure.

Toxins

• Another theory suggests that toxins, whether external or internal, are what destroy these dopamine-producing nerve cells. Some evidence supports the idea that the chemical, MPTP, found in narcotics, may cause Parkinson's. Researchers in the book "Basic Neurochemistry, 6th edition, Molecular, Cellular and Medical Aspects," describe how drug users induced Parkinson's-like symptoms after inadvertently administering MPTP. However, there is currently not enough evidence to say definitively if toxins are a possible cause.

Genetic Factors

• Genetic factors may play a part in Parkinson's disease.

  Genetic factors as a role in Parkinson's is another theory. Fifteen to 20 percent of patients with Parkinson's have a close relative with Parkinson's-like symptoms. Researchers have targeted a mutation in the PARK2 gene that may cause Parkinson's, according to the University of Utah Spencer C. Eccles Health Sciences Library.

PARK2 and Parkin

• A normally functioning PARK2 gene, reports the Genetics Home Reference, provides instructions for the creation of parkin, a protein responsible for breaking down unwanted proteins. Parkin may help suppress tumor proteins and regulate the nerve cells' transmission of signals to one other. How a mutated PARK2 gene causes Parkinson's still isn't clear. The subsequent loss of parkin activity could cause a buildup of unwanted proteins, which may compromise the release of dopamine. Alternatively, since the brain normally has an abundance of parkin, its paucity could be due to the death of nerve cells.