London - People who take cocaine over many years without becoming addicted have their brains to thank, a study has found.
Researchers found recreational drug users who do not develop a dependence have an abnormally large frontal lobe, the section of the brain implicated in self-control.
The Cambridge University study asked individuals who used cocaine on a regular basis to undergo a brain scan and complete a series of personality tests. While the majority of the cocaine users were addicted to the drug, there were some who were not despite having used it for several years.
The scientists 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 these recreational cocaine users.
They suggested that this abnormal increase in grey matter volume, which they believe predates drug use, might reflect resilience to the effects of cocaine.
The team found that the same region was significantly reduced in size in people with cocaine dependence. However, they believe at least some of these changes were the result of drug use, which eroded what self-control they had.
Study leader Dr Karen Ersche, said: “Drug addiction never happens overnight. It needs continued use to take hold as a habit.”
The personality tests revealed that people who developed a dependence had two traits that could be harmful when combined – that of being impulsive and compulsive. This gave them an often uncontrollable urge to act without thinking as well as a need to repeat behaviours that then became habits.
In contrast those who didn’t become addicted were sensation-seekers like addicts, however they also became bored quickly and moved on to other behaviours and experiences.
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.
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.”
Their research was published in the journal Biological Psychiatry. – Daily Mail