"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 more we discover about the neurobiology of addiction the more common elements we're seeing between THC (tetrahydrocannabinol, the main active ingredient in cannabis) and other drugs of abuse." And for Koob, one of these newly discovered "common elements" is marijauna's ability to trigger chemical changes in the brain that lead to strong withdrawal symptoms.
In humans, some researchers claim to see clear evidence of insomnia, anxiety and even flu-like symptoms in heavy cannabis users who abstain. But if there's a consensus, it's that symptoms are mild and variable. By contrast, Koob's rats are shivering wrecks. Does this mean marijuana is more addictive than we think?
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