A gene alteration seems to influence the preference of cocaine addicts for the most harmful form of the drug: crack, or rock cocaine, which is usually smoked. Researchers at the University of São Paulo (USP) and the Federal University of São Paulo (Unifesp) reached this conclusion by comparing the most frequent alterations in the gene that stores the information for producing the enzyme butyrylcholinesterase (BCHE) and the consumption habits of 698 cocaine addicts in the city of São Paulo. Synthesized mainly by the liver, BCHE breaks cocaine up in the blood, turning it into two inert compounds. Therefore, the larger the amount of the active form of the enzyme, the lower the dose of cocaine which reaches the brain, resulting in a less intense drug effect. Researchers compared the frequency of the three mutations in the BCHE gene to the preferred form of cocaine use: snorted (powder), inhaled (crack) or both. They saw that users with a specific mutation—rs1803274, which reduces the enzyme’s activity—in the two copies of the BCHE gene were more likely to use crack than cocaine in powdered form (PloS One, November 27, 2013). This mutation is not seen as a direct cause of addiction, but rather influences the preference for inhaled cocaine.
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