Lowered dopamine transmission disrupts corticostriatal functional connectivity , top-down regulation by the cortex and the ability of reward related cues to activate the striatum [63-64]. These neurophysiological effects are associated with a decreased behavioral tendency to preferentially respond to rewards [65-67], and a decreased willingness to sustain effort to obtain rewards, including alcohol , tobacco  and money . Elevated dopamine function, in comparison, increases the ability of reward related cues to guide behavioral choices , diminishes the ability to differentiate between high and low value rewards , and induces steeper temporal discounting, a form of impulsivity defined by preference for immediately available small rewards over larger, more distal ones . In clinical populations, patients with schizophrenia – considered a hyper-dopamine disease – have very high rates of substance use problems  while those with Parkinson’s disease exhibit, if anything, decreased rates of substance abuse . Indeed, administering Parkinson’s patients dopamine agonist medications can induce a dysregulation syndrome characterized by various impulse-control problems, including pathological gambling, hyper-sexuality, and substance abuse .