IOM's Marijuana and Medicine: Assessing the Science Base (1999)

"At this point, our knowledge about the biology of marijuana and cannabinoids allows us to make some general conclusions:
"· Cannabinoids likely have a natural role in pain modulation, control of movement, and memory.
"· The natural role of cannabinoids in immune systems is likely multi-faceted and remains unclear.
"· The brain develops tolerance to cannabinoids.
"· Animal research demonstrates the potential for dependence, but this potential is observed under a narrower range of conditions than with benzodiazepines, opiates, cocaine, or nicotine.
"· Withdrawal symptoms can be observed in animals but appear to be mild compared to opiates or benzodiazepines, such as diazepam (Valium)."

Source

Janet E. Joy, Stanley J. Watson, Jr., and John A Benson, Jr., "Marijuana and Medicine: Assessing the Science Base," Division of Neuroscience and Behavioral Research, Institute of Medicine (Washington, DC: National Academy Press, 1999), p. 3.
http://books.nap.edu/openbook…