Research led by the University of Warwick has identified areas of the brain that are different in those who smoke and those who drink: the tendency to drink alcohol is associated with increased connectivity of brain networks associated with reward processing; and the tendency to smoke is associated with low connectivity of systems that respond to not receiving rewards. These differential tendencies to alcohol and nicotine consumption can even be detected in young people before much drinking or smoking has started.
In 2,000 participants they found that smokers had low functional connectivity in general, and especially in the lateral orbitofrontal cortex, a region of the brain associated with impulsive behaviour. This suggests that people who smoke may do so to increase their overall brain connectivity with the stimulating effect of nicotine; and that being impulsive may be a factor leading to smoking.
Drinkers of alcohol had high overall brain connectivity, especially in the medial orbitofrontal cortex, a region implicated in reward. It is suggested that the high connectivity of this reward-related brain region may be a factor in attracting some individuals to alcohol. Importantly the extent of these functional connectivity changes in the brains of drinkers and smokers correlated with the amount of alcohol and nicotine being consumed.