Throughout the world, between seven and 10 million people have Parkinson’s disease, a neurological disorder resulting from damage to neurons that produce dopamine, according to the Parkinson’s Disease Foundation.
A neurotransmitter, dopamine transmits information between two areas of the brain — the substantia nigra and corpus striatum — which produce movement. With Parkinson’s disease, the neurons that produce dopamine become impaired or destroyed, decreasing the amount of dopamine in the brain.
The National Institute of Neurological Disorders and Stroke noted that when symptoms of the disorder appear, patients have lost between 60 and 80 percent of the dopamine-producing neurons in the substantia nigra. The drop in dopamine affects communication between the substantia nigra and corpus striatum, resulting in movement problems seen with the disorder, such as impaired balance, slowness of movement, tremors and rigidity.
Patients with Parkinson’s disease may be at risk for other conditions. In a meta-analysis conducted by Liu et al., the authors found a relationship between Parkinson’s disease and melanoma.
A dangerous skin cancer, melanoma is involved with a type of cell called melanocytes, which are responsible for the production of melanin. The National Cancer Institute estimated that in 2011, doctors will diagnose 70,230 new cases of melanoma, and 8,790 will be fatal. Four types of melanoma exist: superficial spreading melanoma (the most common), acral lentiginous melanoma (the least common), nodular melanoma and lentigo maligna melanoma.
The study, which was published in the June 7th issue of Neurology, performed a systematic review using Embase, PubMed, Scoups and Web of Science on articles on Parkinson’s disease and melanoma from 1965 to June 2010 and found 12 publications that met criteria. The authors found a connection between Parkinson’s disease and a higher rate of melanoma, which was bidirectional — meaning Parkinson’s disease patients have a higher likelihood of developing melanoma, as patients with melanoma have a higher likelihood of developing Parkinson’s disease; they did not find a connection between Parkinson’s disease and non-melanoma skin cancer.
There is no definite answer why these two conditions occur together, though several theories exist, including genetic and environmental risk factors.
In the HealthDay News report, lead research Dr. Honglei Chen noted that the odds of having both conditions are around 4 percent.
Parkinson’s Disease Foundation. Statistics on Parkinson’s. Web. 25 July 2011
National Institute of Neurological Disorders and Stroke. Parkinson’s Disease: Hope Through Research. National Institutes of Health, 2011. Web. 25 July 2011
National Cancer Institute. Melanoma Home Page. National Institutes of Health. Web. 25 July 2011
A.D.A.M. Melanoma. MedlinePlus, 2011. Web. 25 July 2011
Liu, R., Gao, X., Lu, Y. and Honglei, C. Meta-Analysis of the Relationship Between Parkinson’s Disease and Melanoma. Neurology, 7 June 2011. Web. 25 July 2011
Reinberg, Steven. Parkinson’s Disease May Boost Melanoma Risk: Study. HealthDay News, 6 June 2011. Web. 25 July 2011
Reviewed July 26, 2011
by Michele Blacksberg R.N.
Edited by Shannon Koehle