COLUMBUS, Ohio Nearly one in five whites could carry a genetic variant that substantially increases their odds of being susceptible to severe cocaine abuse, according to new research.
This genetic variant, characterized by one or both of two tiny gene mutations, alters the brain's response to specific chemical signals. In the study, led by Ohio State University researchers, the variant was associated with a more than threefold increase in the odds that carriers will be susceptible to severe cocaine abuse leading to fatal overdosing, compared to non-carriers.
Among whites, one or both mutations were found in more than 40 percent of autopsy brain samples taken from people who had abused cocaine, compared to 19 percent of samples from people who lived drug-free. Overall, one in five samples from whites in the control group and one in two to three samples in the cocaine overdose group contained the genetic variant, compared to one in eight African Americans, in whom the variant is less prevalent.
The mutations either alone or in combination affect how dopamine modulates brain activity. Dopamine, a neurotransmitter, is a chemical messenger vital to the regular function of the central nervous system. Previous research has established that cocaine blocks dopamine transporters from absorbing dopamine after its release, leaving the chemical outside the brain cells and creating a feeling of euphoria.
In people who carry one or both of the mutations, the function of a gene responsible for transmitting dopamine signals in the brain is altered. Researchers speculate that this altered gene function sets up a vicious circle of chemical signals that could lead to a craving for a substance that can maintain elevated levels of dopamine in the brain.
The researchers say many questions about cocaine abuse susceptibility remain unanswered: Do the mutations increase the chances someone will try cocaine in the first place? Or do they
|Contact: Wolfgang Sadee|
Ohio State University