BUMPING into former drug buddies, glimpsing drug users or passing an old haunt induces cravings that remind recovering cocaine addicts of their old habits and make them want to go back to the drug. The chemical responsible for such cravings has now been identified, and that could lead to more effective rehabilitation.
Snorting or smoking cocaine triggers the production of dopamine in the brain鈥檚 pleasure centre, the nucleus accumbens, causing a feeling of reward that gives addicts a high and hooks them. Now Nora Volkow at the US National Institute on Alcohol Abuse and Alcoholism in Bethesda, Maryland, and colleagues have shown that dopamine also triggers cravings by bonding to receptors in a brain region associated with motivation, the dorsal striatum (The Journal of Neuroscience, vol 26, p 6583).
When 18 cocaine addicts watched a 40-minute movie that featured people buying and preparing a substance that looked like cocaine, brain scans showed they produced more dopamine in the dorsal striatum than when they viewed a nature film. The effect was more marked in the most strongly addicted people. Volkow鈥檚 team says that cocaine hijacks 鈥渃raving machinery鈥� that evolved to ensure we take advantage of available food.
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