Parkinson's disease

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.

Parkinson's disease has no single cause; rather, genetic and environmental factors interact to affect critical cellular processes. Parkinson's disease involves the gradual decay and loss of dopamine-producing neurons in a brain region called the substantia nigra and other related cell groups in the brainstem. Misfolded proteins, such as alpha-synuclein, aggregate to form clumps called Lewy bodies, if not cleared from cells by cellular degradation systems. Protein accumulation stimulates the release of pro-inflammatory molecules by the microglia, a protective response that can cause neuroinflammation, further neuronal damage, and disruption of metabolic systems, if remaining chronic.