Original sentence: Most of the research on gene regulation and addiction is based upon animal studies with intravenous amphetamine administration at very high doses.The effects of amphetamine on gene regulation are both dose- and route-dependent.The few studies that have used equivalent (weight-adjusted) human therapeutic doses and oral administration show that these changes, if they occur, are relatively minor
Edited sentence: Prolonged treatment with stimulants causes changes in genes which are qualitatively similar to the changes seen with prolonged cocaine and illicit methamphetamine use