Pathology of Parkinson’s
Parkinson’s disease is caused by the death of neurons in a part of the brain known as the substantia nigra. This area of the brain is part of a system of neurons known as the basal ganglia. This system is very important in the control of movement. The neurons in the substantia nigra secrete dopamine. The loss of dopamine’s effect on the basal ganglia leads to the signs and symptoms of Parkinsonism.
Abnormalities are also seen in the neurons of individuals with Parkinson’s. These abnormalities are called Lewy bodies. These bodies are collections of abnormal proteins that clump together to form a redish-pink mass in the cytoplasm of the substantia nigra neurons.
Unfortunately, it is not known what causes most cases of Parkinson’s disease. However, there are some known causes, almost all of which involve damage to the substantia nigra. Toxins like carbon disulfide and certain street drugs have been known to kill dopamine secreting neurons resulting in Parkinson’s. Another toxin known as MPTP, which was produced accidentally by drug chemists trying to illegally make a synthetic heroin derivative, is extremely toxic to substantia nigra cells. It caused irreversible Parkinson’s disease in those who were unfortunate enough to ingest it.
Finally, the genetics of Parkinson’s disease are not well known. There appears to be multiple genetic causes of the disease. One gene mutation involves α-synuclein, a protein that forms the main component of Lewy bodies. Other genetic mutations may also play a role in Parkinson’s, but they contribute only a small fraction of the total number of cases.