SNIFFING the vapour from glue, lighter fuel and other hydrocarbon solvents is one of the most widespread and damaging forms of substance abuse. Now the world鈥檚 first images of how an inhaled solvent spreads through the brain may help reveal why these substances are so addictive.
Stephen Dewey and his colleagues at Brookhaven National Laboratory in New York looked at how toluene鈥攆ound in paints, glues and other household products鈥攖ravels through the brain. They exposed mice and baboons to toluene labelled with a radioactive isotope, carbon-11, and then used PET scans to follow the chemical鈥檚 path.
Dewey expected the solvent to be evenly distributed around the brain. But to his surprise, this is not what happened. It first travels to the regions of the brain associated with reward and pleasure鈥攖he same regions affected by drugs such as cocaine. This might explain why such solvents are addictive, the researchers say.
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Immediately afterwards, however, toluene spreads throughout the white matter of the brain鈥攖he myelin underneath the grey matter鈥攁nd stays there for up to a few minutes. 鈥淲e think that鈥檚 why you get the long-term effects,鈥� says Madina Gerasimov, a scientist at Brookhaven.
It鈥檚 a big jump from these experiments to understanding solvent abuse in people, but 鈥渋t鈥檚 an important first step鈥�, says pharmacologist Robert Balster of Virginia Commonwealth University in Richmond. He says solvents are more commonly used among young people than heroin or cocaine, and do more harm.