Coauthor of the study, Nelly Alia-Klein, a Brookhaven Lab medical scientist, said that, "This research shows that genes can influence the severity of addiction. The results suggest that addicted individuals with low MAOA [monoamine oxidase A] genotype may need a different kind of treatment than other addicted individuals who carry the high MAOA genotype. More studies need to be conducted before implementing changes in treatment strategies.”
This study confirms the findings of previous studies that cocaine-addicted individuals, relative to non-addicted individuals, have lower gray matter density in frontal parts of the brain - which is important for paying attention and organizing one's own behavior - and in the hippocampus, a brain region important for learning and memory.
What this study also found was a pattern of low gray matter that correlated with the number of years of alcohol, cocaine and cigarette use in the addicted group. This result means that curtailing drug use may be protective against such brain changes.
This study was conducted with a group of 82 men 40 of whom were cocaine addicts and 42 of which were controls. All of the participants were given physical/neurological, psychiatric and neuropsychological examinations, including tests of intellectual functioning, and all the men were healthy and not taking medication. The researchers scanned the subjects' brains using a MRI, and a method called voxel-based morphometry enabled the researchers to determine the proportion/density of gray matter (as an estimation of neuron density) in the whole brain. The gray matter volume was then compared between the groups and correlated with genetic type and duration of drug use.
DOE/Brookhaven National Laboratory