1. A method for reducing drug side effects on a patient, comprising: determining an aspect of the patient's functioning that is negatively affected by a drug in which the patient consumes as part of a therapy to treat a movement disorder or to treat symptoms associated with a movement disorder; positioning at least one electrode device having a plurality of electrical contacts such that at least one electrical contact is positioned below the patient's skull on the dura over a target cortical location selected from the group consisting of prefrontal cortex, supplemental motor cortex and motor cortex; and applying electrical stimulation to the cortical region of the patient's brain that is associated with the functioning such that the electrical stimulation reduces the drug side effects.