Jeremy has Parkinson’s disease, a progressive neurodegenerative disease that affects motor skills. In addition to motor symptoms, Jeremy has noticed changes in his mood, and he feels the need to smoke...

Jeremy has Parkinson’s disease, a progressive neurodegenerative disease that affects motor skills. In addition to motor symptoms, Jeremy has noticed changes in his mood, and he feels the need to smoke more cigarettes than he used to. It is likely that Jeremy’s ________ is producing less ________ than it needs to.