RT Book, Section A1 Faulkner, Michele A. A2 Sutton, S. Scott SR Print(0) ID 1188113101 T1 Parkinson Disease T2 McGraw Hill’s NAPLEX® Review Guide, 4e YR 2020 FD 2020 PB McGraw-Hill Education PP New York, NY SN 9781264258062 LK accesspharmacy.mhmedical.com/content.aspx?aid=1188113101 RD 2024/03/29 AB Parkinson disease (PD) also called Parkinson's disease, is a slow, progressive neurodegenerative disease of the extrapyramidal motor system for which there is presently no cure. The disorder results from the loss of nigrostriatal neurons in the substantia nigra pars compacta and Lewy body formation (misfolded proteins). By the time symptoms emerge and a diagnosis is made, it is estimated that 80% of nigrostriatal neurons have been lost. Due to a resultant deficiency in the neurotransmitter dopamine, there is less inhibitory output from the basal ganglia allowing for overactivity of acetylcholine. The neurotransmitter imbalance is responsible for the motor function abnormalities that characterize PD. The cardinal features of PD include tremor, bradykinesia, rigidity, and postural instability (though this symptom is rare in the early stages of the disease). PD symptoms typically begin unilaterally and spread to the opposite side as the disease progresses. Presentation varies among individuals and can differ substantially from person to person.