Students are very interested in learning about the effects of specific substances upon their bodies. Do specific chemicals stimulate or inhibit normal neurologic response? Can we find out without using ourselves as guinea pigs? Sure!
There are a number of "safe" labs that students can perform in their science classes on this topic. An activity that has been very successfully utilized in our school's tenth grade Topics in Medicine elective is Daphnia on Drugs.
The Eight Intelligences Link, some thoughts on diversity for this lesson.