Explanations for nicotine addiction
An explanation based on brain neurochemistry centres on the role of the neurotransmitter dopamine in boosting the brain’s reward system, due to smoking behaviour creating pleasant sensations. The stimulation of dopamine neurons triggers activation in the limbic system, which in turn boosts activity in the pre-frontal cortex creating a euphoric ’high’. Through repeated usage the level of nicotine needed to produce the high becomes greater, with cravings created that result in addiction. With learning theory smoking behaviour is explained as a two-stage process involving social learning theory and operant conditioning. An individual is seen as initiating smoking behaviour through the observation and imitation of smoking role models via the use of vicarious reinforcement (seeing the model being positively reinforced for their smoking behaviour). Continuation of smoking behaviour then occurs by the positive reinforcement that consuming nicotine incurs in the form of pleasurable sensations and the reduction of anxiety. Cue reactivity involves associations that are made through classical conditioning, such as smoking when having a drink in the pub beer garden, with the drink/location acting as a conditioned stimulus, creating a strong desire to smoke (conditioned response) in such situations.
Fig 17.2 Are certain personalities more predisposed to addiction?
Goldberg et al. (1981) performed a laboratory experiment that assessed the role of operant conditioning in addictive behaviour in squirrel monkeys. The monkeys were trained to press a lever in order to receive a positive reinforcement of a nicotine injection and their response rate was compared to the response rate exhibited by a group of similar squirrel monkeys who had been trained to press a lever to receive a positive reinforcement of an injection of cocaine. It was found that both groups of monkeys produced similar levels of response when pressing the lever. This illustrates the important role that operant conditioning plays in the maintenance of addictive behaviour and demonstrates that addictive behaviours are indulged in, due to their positively reinforcing effects.
• Chiara (2000) reported that dopamine is one of the main causes for the addictive nature of nicotine. The rewarding aspect of the drug, such as the feeling of pleasure, is released through dopaminergic activity and so is responsible for the addictive nature of the drug. If pleasure was not felt then the smoker would not continue to smoke over time. This illustrates the important role of brain neurochemistry in smoking behaviour.
• Watkins et al. (2000) reviewed the research into the neurobiology of nicotine addiction. They found that dopamine release was reduced following chronic exposure to nicotine. This means that tolerance of the drug occurs due to the level of reward felt decreasing. This illustrates how nicotine consumption increases to the point of addiction due to brain neurochemistry.
• Calvert (2009) found that smokers, when shown cigarette packets, experienced strong activation in the ventral striatum and nucleus accumbens brain areas, suggesting a biological explanation of craving behaviour. However, this also supports the idea of cue reactivity and therefore the brain activation produced may show the neural basis for classical conditioning.
The role of dopamine in smoking behaviour suggests a genetic link to addiction. It is possible that the dopaminergic mechanism in some individuals leads them to feel the rewarding aspects of drugs to a greater level because they have an inherited tendency to do so.
Research evidence suggests social learning theory is the best explanation for initiation of smoking behaviour. Individuals must be motivated to try smoking initially for it to become classically or operant conditioned and this is only accounted for through social learning theory.
Brain neurochemistry and learning explanations are probably best viewed not as separate explanations, but as explanations that can be amalgamated together to produce a more valid explanation.
The dopamine explanation for addiction is purely biological and, as a consequence, ignores the psychological aspects of addiction. It is likely that dopamine, although implicated, is not the whole picture and other factors should be considered in understanding addiction to smoking behaviour.
Research evidence from animal studies is mainly used when investigating learning theory and addiction, which creates problems of generalisation to humans. For instance, there are cognitive elements to social leaning theory that are not really considered when performing such research on animals. This lowers the validity of the explanation.
The main practical applications of research into explanations for smoking behaviour is the development of therapies to stop smoking behaviour based on such explanations. For example, the development of drugs that mimic the action of nicotine upon the brain’s reward system, but without producing nicotine’s harmful effects.