Biological Explanations of Addictive Behaviour
This explanation is easier to apply to chemical addictions such as nicotine as opposed to behavioural addictions like gambling. It focuses on the role of neurotransmitter substances in the brain along with genetic differences between those with addictions and those without.
A neurotransmitter is a chemical that moves across the gaps between nerve cells to transmit messages. If this chemical is blocked or replaced then the message changes and there is an effect on the physiological systems along with cognition, mood and behaviour. The neurotransmitter most commonly implicated is dopamine, but other chemicals also have been found to have a role. Whilst their role is most notable in chemical addictions, they have been implicated into behaviours such as gambling and playing video games.
Family studies tend to emphasise the role of environmental factors in developing addictions, for instance, a study of 300+ MZ twins and just under 200 DZ twins estimated the contribution of genetic and environmental factors to substance use in adolescence. It concluded that the major influences on the decision to abuse substances were environmental rather than genetic (Han 1999).
Some family studies however, suggest a link between addiction and personality traits, e.g. a study of MZ and DZ twins looked at the relationship between alcohol use and personality. Its conclusion suggested that there is a connection between genetics and the characteristics of anti-social personality and between these characteristics and alcoholism (Jang 2000). Similar findings have been found for behavioural addictions.
McGue 1999 found that genes contribute to the development of alcoholism with estimates of 50-60%. Argrawal & Lynskey 2006 found that drug dependence is affected by genetics for about 45-79%.
Vink found that smoking dependence is roughly 75% genetic and 25% environmental.
The biological explanation overlaps with the behavioural in this instance. Reinforcement is anything that increases the probability that the behaviour will recur in similar circumstances. This is linked to the 'pleasure centres' in the brain. Olds & Milner 1954 found that rats would press a lever for a reward of mild electrical stimulation in particular areas of the brain (pleasure centres). They would continue to press in preference of other rewards such as food or sex. These feelings of pleasure act as reinforcement.
Initiation - A genetic vulnerability may be triggered by some…