It is a slowly progressing neurodegenerative disease associated with abnormal functioning of the extrapyramidal system. There can be multiple causes for it, and both genetic and biochemical alterations are to blame.

Tremor, stiffness, and slow movements, associated with the progressive neuronal loss of the black matter and other brain structures, characterize this disease. The neurons with more severe compromise are those responsible for synthesizing or producing dopamine, a neurotransmitter involved in movement control or regulation functions, with a significant participation in attention, memory, and motivation as well.

The neurophysiological studies usually detect alterations in these functions, appearing abnormal in movement planning, hand-eye coordination, attention, memory, and motivation. On the other hand, frontal lobe and basal ganglia alterations can also produce similar symptoms or signs to dopamine deficit, generating equivalent clinical conditions.