Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor and non-motor systems. The motor symptoms, collectively called parkinsonism, include tremors, slowness in initiating movement (bradykinesia), rigidity, and difficulty maintaining balance (postural instability). Non-motor symptoms such as autonomic nervous system failures (dysautonomia), sleep abnormalities, decreased ability to smell (anosmia), and behavioral changes or neuropsychiatric problems, such as cognitive impairment, psychosis, and anxiety, may appear at any stage of the disease. Symptoms typically develop gradually and non-motor issues become more prevalent as the disease progresses.
Most Parkinson's disease cases are idiopathic, though contributing factors have been identified. Pathophysiology involves progressive degeneration of nerve cells in the substantia nigra, a midbrain region that provides dopamine to the basal ganglia, a system involved in voluntary motor control. The cause of this cell death is poorly understood, but involves the aggregation of alpha-synuclein into Lewy bodies within neurons. Other potential factors involve genetic and environmental influences, medications, lifestyle, and prior health conditions.
