Smoking 'primes the brain for cocaine cravings'

Smoking may increase the chances of someone abusing cocaine later in life by priming the brain to be more receptive to the Class A drug, say scientists.
The landmark study, from the National Institute on Drug Abuse in Maryland, is the first to show how nicotine can change the brain in a way that enhances the behavioural effects of cocaine.
It could help explain why so many drug-using teenagers tend to start with cigarettes and alcohol before moving on to more illegal substances.
In the current study, scientists from Columbia University in New York, found mice exposed to nicotine through their drinking water for one week showed an increased response to cocaine.
This priming effect depended on the previously unrecognised impact that nicotine made on gene expression. It was found to reprogram specific genes linked to addiction ultimately making the brain more responsive to harder drugs.
The team found that the results paralleled findings in humans after they reexamined statistics from the 2003 National Epidemiological Study of Alcohol Related Consequences.
They found that the rate of cocaine dependence was higher among cocaine users who smoked prior to starting cocaine compared to those who tried cocaine prior to smoking.
The findings, published in Science Translational Medicine, suggest smoking prevention would not only prevent the damaging effects of the habit but could also decrease the risk of progression and addiction to cocaine and other illegal drugs.
Senior author, Dr Eric Kandel, said: 'Now that we have a mouse model of the actions of nicotine as a gateway drug this will allow us to explore the molecular mechanisms by which alcohol and marijuana might act as gateway drugs.
'In particular, we would be interested in knowing if there is a single, common mechanism for all gateway drugs or if each drug utilises a distinct mechanism.'