People who take cocaine over many years without becoming addicted have a brain structure which is significantly different from those individuals who developed cocaine-dependence, a study from the Department has found.
The research, led by Dr Karen Ersche, was published in the journal Biological Psychiatry and shows that recreational cocaine users who have not developed a dependence have an abnormally large frontal lobe, a section of the brain implicated in self-control.
For the study, individuals who regularly use cocaine underwent a brain scan and completed a series of personality tests. These individuals were split into two groups: those who were cocaine dependent, and those who were not addicted. The groups were then compared to non-addicted siblings and unrelated healthy volunteers.
Dr Ersche and colleagues discovered that a region in the frontal lobes of the brain, known to be critically implicated in decision-making and self-control, was abnormally bigger in the non-dependent recreational cocaine users. The research team suggest that this abnormal increase in grey matter volume, which they believe predates drug use, might reflect resilience to the effects of cocaine, and even possibly helps these recreational cocaine users to exert self-control and to make advantageous decisions which minimise the risk of them becoming addicted.
The study also found that this same region in the frontal lobes of the brain was significantly reduced in size in people with cocaine dependence. The authors believe that at least some of these brain changes are the result of drug use, which causes the user to lose grey matter.
They also found that people who use illicit drugs like cocaine exhibit high levels of sensation-seeking personality traits, but only those developing dependence show personality traits of impulsivity and compulsivity.
Dr Ersche said: “These findings are important because they show that the use of cocaine does not inevitably lead to addiction in people with good self-control and no familial risk.
“Our findings indicate that preventative strategies might be more effective if they were tailored more closely to those individuals at risk according to their personality profile and brain structure.”
The researchers will next explore the basis of the recreational users’ apparent resilience to drug dependence.
Dr Ersche added: “Their high level of education, less troubled family background or the beginning of drug-taking only after puberty may all play a role.”
This work was funded by a Medical Research Council and received institutional funds from the Behavioural and Clinical Neuroscience Institute (BCNI), which is jointly funded by the Medical Research Council and the Wellcome Trust.
Adapted from a press release by the University of Cambridge