Problem: Parkinson's disease is a chronic, progressive neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta, with accumulation of misfolded α-synuclein (Lewy bodies) in central and peripheral nervous system regions. The cardinal motor features - bradykinesia, rigidity, resting tremor, and postural instability - emerge once approximately half of dopaminergic neurons in the caudal substantia nigra are lost. These symptoms begin asymmetrically and gradually become bilateral, eventually leading to functional impairment, loss of independence, falls, and fractures. The transition from impairment to disability typically occurs 3-7 years after onset. Nonmotor symptoms often precede motor signs by years to decades, including REM sleep behavior disorder, hyposmia, constipation, depression, and autonomic dysfunction. This extended prodromal period underscores the slowly evolving nature of the underlying neurodegeneration. Cognitive decline: Mild cognitive impairment develops at ~10% per year; cumulative dementia probability is 46% at 10 years and 83% among 20-year survivors Neuropsychiatric symptoms: Anxiety (60%), apathy (60%), depression (35%), psychosis (~40%, usually later stages) Autonomic dysfunction: Orthostatic hypotension, constipation, urinary dysfunction, erectile dysfunction, and impaired thermoregulation rewrite and shorten. Need Assignment Help?