3 - Biological Theory explanation for nicotine addiction

brain neurochemistry, including the role of dopamine

Brain neurochemistry explanation (AO1)

• nicotine reaches peak levels in the bloodstream and the brain in less than 10 seconds

• nicotine binds with receptors in the ventral tegmental area (VTA).

• triggers release of dopamine in the nucleus accumbens in the mesolimbic system, boosting activity in the prefrontal cortex

• nicotine causes glutamate to speed up dopamine release. GABA normally slows down neuron activity, but nicotine inhibits this

• lots of dopamine remains in the synapses

• dopamine receptors on neurons are stimulated giving the person pleasure

• once the dopamine is removed via reuptake, the feeling disappears and the person will want to use more nicotine

• if usage is consistent, the body becomes tolerant to the high levels of dopamine

• dopamine reuptake increases, and the feeling of pleasure doesn’t last as long

• if the person stops using nicotine they experience withdrawal syndrome, but effects can be relieved by smoking again

• maintains their addiction and cause them to relapse

• These changes (neuroadaptation) can take months or years to be reversed

Brain neurochemistry explanation (AO3) - self administration in rats

A strength of the theory is that there is research evidence to support it

Corrigall and Coen (1991)

• found that rats would self-administer nicotine into reward centres of the brain

• injecting the rats with a drug that prevents dopamine release decreased nicotine self-administration

suggests that the rats were addicted to the nicotine assuming the reward pathway is fully completed

strengthens the theory of brain neurochemistry to explain nicotine addiction

however the rats were in a cage in a lab environment with little stimulation so they might be more inclined to self-administer nicotine as they have no other source of dopamine

weakens the usefulness of the research in supporting the brain neurochemistry explanation

Brain neurochemistry explanation (AO3) - tolerance

A strength of the theory is there is research evidence to support it

Watkins et al. (2000)

• found dopamine release was reduced following chronic exposure to nicotine

suggests that tolerance occurs due to the level of reward decreasing

strengthens the usefulness of the theory

Brain neurochemistry explanation (AO3) - gender differences

A limitation of the theory is that there are gender differences in how nicotine affects the brain

Cosgrove et al. (2014)

• studied the brains of 8 men and 8 women using positron emission topography (PET) scans to measure changing levels of dopamine when smoking

• men had a rapid and strong activation in the ventral striatum

• women had a rapid and strong dopamine effect in the dorsal putamen

Concluded that men and women smoke for different reasons - men for the nicotine effect and women to relieve stress

suggests that the theory has beta bias where it assumes nicotine affects everyone the same, even when there are gender differences

limits the usefulness of the theory

Brain neurochemistry explanation (AO3) - not the only explanation

A limitation of this is there is real world application to suggest other factors may impact nicotine addiction

Calvert (2009)

• found that smokers that were shown cigarette packets experienced activation in the ventral striatum and nucleus accumbens

suggests there is also a learning theory explanation, cue reactivity, to explain nicotine addiction as they were activated by cues, instead of the actual presence of nicotine

research incentivised the UK government to make cigarette packets unappealing, showing the damaging effects of smoking instead of brands, to help reduce the impact of cues in maintaining addiction. Also moving cigarettes behind the cashier in shops to help disincentivise smokers

strengthens the usefulness of this theory