The main disease associated with low brain dopamine is Parkinson's disease. In this degenerative condition, production in the 'substantia nigra of the brain stem' (the region of the brain in which it acts) decays rapidly, resulting in impaired communication of neurons responsible for motor system modulation.
One of the functions of dopamine is to control voluntary movements, thus its deficiency leads to the difficulty of movement characteristic of Parkinson, which is marked by stiffness and tremors.
