Parkinsonism etiology

The cause of Parkinson disease is unknown for most patients. The disease is correlated with destruction of dopaminergic neurons in the substantia nigra with a consequent reduction of dopamine actions in the corpus striatum, parts of the brain’s basal ganglia system that are involved in motor control. The loss of dopamine neurons in the substantia nigra is evidenced by diminished overall uptake of dopamine precursors in this region, which can be visualized using positron-emission tomography and the dopamine analog fluorodopa. Genetic factors do not play a dominant role in the etiology of Parkinson disease, although they may exert some influence on an individual’s susceptibility to the disease. It appears increasingly likely that an as-yet unidentified environmental factor may play a role in the loss of dopaminergic neurons.