Richard A. Rawson, Ph.D is an Adjunct Associate Professor in the Department of Psychiatry and Biobehavioral Sciences at the David Geffen School of Medicine, University of California at Los Angeles.

In this audio slideshow, Dr. Rawson explains how meth affects the brain's dopamine receptors, causing the intense pleasure associated with a meth rush and yet eventually making it impossible for the user to experience pleasure at all.