"Epidemiology of Parkinson's Disease" by de Lau and Breteler in 2006 defined statistics for Parkinson's disease (PD) stating that this is a fairly common neurological disorder currently affecting about 350 per 100,000 individuals. With technology, medical advancements, and the human lifespan being much longer today it is not a surprise to find that cases are on the rise. Roughly 95 percent of PD cases are among those over the age of 60, and primarily male.
Substantia Nigra
PD is a neurological disorder. The neuronal loss occurring with disease progression in the substantia nigra affects the brain stem areas comprised of the locus cerelus, dorsal vagal nucleus, and sympathetic ganglia. According to the National Institute of Neurological Disorder and Stroke, the presence of Lewy bodies (abnormal intracytoplasmic eosinophilic neuronal inclusion bodies responsible for cell loss and decline in cognitive function) eventually depletes or impairs dopamine stores in the brain, resulting in dementia in some cases.
Absence of Dopamine
This absence of dopamine by 60 to 80 percent in the brain resulting in a lack of relay to the corpus striatum is responsible for smooth motor movements. According to Parkinson's.Org, those with the disorder may also exhibit behavioral and pharmacological difficulties in treatment that may include anger, missing appointments, shutting down or rejecting social supports, dementia, depressed moods, anxiety, apathy, and prescription drug-related complicating factors. Caring Medical and Rehabilitative Services posits that dopamine depletion in PD is the contribution to the experiences of muscle rigidity, flat facial expressions, immobility, slowed reaction times, and tremors.
Genetic Heritability
Immediate family members (i.e., mother, father, siblings) have a higher risk of getting PD with a two to three-fold incident rate. This is only 5 percent of the roughly 1 million individuals already living with the disorder. The Parkinson's Disease Foundation lists 13 known genes attributed to the disorder as follows: PARK1, DJ-1 (PARK 7), Pink1 (PARK 6), dardarin (DRDN), Fau, Irrk2, parkin, uchl-1, park3, park9, park10, and park11.
Environmental Conditions
PD has been the subject of numerous speculations about environmental influences attributed to it. According to the Parkinson's Disease Foundation, no empirical evidence has surfaced to confirm or deny this speculation. One confirmed link beyond genetic influence is associated with an injected synthetic narcotic drug substance known as MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine). Scientists are currently investigating the role and similarities this drug has to herbicides (paraquat) responsible for cell damage already noted in the use of the pesticide rotenone.
