Marijuana In Detail "Marijuana causes long-term changes in the brain similar to those seen with other drugs of abuse . . ." Back in the 1970s, animal experiments led to groundless fears that marijuana blew holes in brain tissue. The experiments organisations like NIDA now fund are more sophisticated but the controversy still rages. George Koob, an addiction researcher from The Scripps Research Institute in La Jolla, California, claims the new message from the animals is simple: "The …showed first 75 words of 1767 total…

…showed last 75 words of 1767 total… the end of the abstinence period, however (Psychopharmacology, vol 143, p 302). The study is the first to measure aggression during withdrawal from a long period of heavy marijuana use. But Margaret Haney, a psychologist at Columbia University in New York, says that people who show aggressive tendencies in the laboratory do not necessarily become violent in the real world. "I would hesitate to say that it would translate to physical violence," she says.