Parkinson's disease is a movement disorder caused by degeneration of neurons in the brain that produce dopamine, leading to an imbalance between dopamine and acetylcholine neurotransmitters. Its main features include bradykinesia, tremors, rigidity, and postural instability. In addition to motor symptoms, it can also cause neuropsychiatric symptoms like depression, anxiety, sleep disturbances, and cognitive impairment. There are also Parkinson-plus syndromes that share similar features but also have additional signs, such as multiple system atrophy which can cause autonomic dysfunction and cerebellar signs in addition to parkinsonism.