Drug addiction linked to availability

When cocaine is readily available, people are more likely to become addicts rather than mere drug users, researchers have found.

Scientists gave rats access to cocaine. One group had an hour's access to the drug in each session; these rats used low and stable amounts of cocaine for many weeks. A second group had access to the drug for six hours at a time; these rats used more and more cocaine.

Rats from the second group also went back for more drugs when the dose was weakened, but cut the number of visits when the cocaine was pure. This suggests that addicts take more and more drugs because they are seeking a higher high, according to the researchers. In addition, they build up a tolerance to the drug and so require a larger dose.

* Science 282