Compared to drugs such as heroin and cocaine, many people consider marijuana a relatively benign substance. But two studies in this issue demonstrate disturbing similarities between marijuana’s effects on the brain and those produced by highly addictive drugs such as cocaine and heroin. One study, described on page 2050, indicates that marijuana withdrawal activates the same stress system in the brain triggered by withdrawal of opiates and alcohol, while the other, reported on page 2048, indicates that marijuana activates the same reward pathway as heroin.

Source : Science 27 June 1997: Vol. 276. no. 5321, pp. 1967 – 1968