Far out. A hallucinogenic compound extracted from this African root (Tabernanthe iboga) could hold the key to curbing drug addiction.

Threat or Therapy?

John is a Science contributing correspondent.

A naturally occurring hallucinogen popular in the 1960s among recreational drug users has long been thought to help curb addiction to harder drugs, but its side-effects have kept it off pharmacy shelves. Now, a new study in rodents provides the first scientific demonstration that the compound, called ibogaine, can help treat alcohol addiction.

Ibogaine is extracted from the root bark of a shrub and is considered sacred by some central African tribes. For decades, maverick doctors have unofficially used it to help alcohol and opiate addicts kick their habits. Users report that their cravings for the substances disappear after a single dose of ibogaine, but they also experience hallucinations and even seizures at high doses. Possession of ibogaine is currently illegal in the U.S.

To see if there is any scientific validity to the claims made about ibogaine, a team led by University of California at San Francisco neurobiologists Dorit Ron and Patricia Janak tested the compound's effect on alcohol-addicted mice and rats. After a single ibogaine injection into their bloodstream, rodents trained to drink alcohol lost interest in the substance--an effect that lasted for weeks.

Another experiment provided more evidence. Scientists believe that addiction to many drugs, including alcohol, is hard to kick because low levels of the neurotransmitter dopamine--which contributes to pleasure--drive addicts back to drugs. A part of the brain called the ventral tegmental area (VTA) is known to be altered in addicts, so the researchers injected ibogaine directly into that part of the rodents' brains. That also kept alcohol addiction at bay. Hinting at a mechanism, the injection elevated levels of GDNF—a molecule necessary for the survival of dopamine-producing neurons. The team reports its findings in the 19 January issue of The Journal of Neuroscience.

"This research is exciting and insightful," says Bill Carlezon, a neuroscientist at Harvard Medical School. But he cautions that changes in GDNF throughout the brain "may not be beneficial," so the next step is to determine if treatment with ibogaine or a similar compound can be tailored to avoid side-effects.

Related sites
Ron's homepage
Janak's homepage
Information on ibogaine

Posted in Brain & Behavior