Cocaine, genes and shrinking brains

People who are addicted to cocaine have less grey matter in the frontal parts of their brain and in their hippocampi. The frontal parts of the brain are important for paying attention and organising one's behaviour while the hippocampus is important in learning and memory. A team of researchers led by Nelly Alia-Klein at the U.S. Department of Energy's Brookhaven National Laboratory have found that people with a certain genetic make up may be more vulnerable to the adverse effects of cocaine use than other people. The researchers studied 82 people. 40 of them were addicted to cocaine and 42 were healthy controls. The researchers took DNA samples and scanned the subjects' brains. The cocaine addicts with a low MAOA (monoamine oxidase A) genotype had lower grey-matter density in the frontal parts of the brain than the other cocaine addicts. The genes are responsible for levels of MAOA, an enzyme which regulates neurotransmitters such as serotonin and dopamine that regulate mood.