A brain-imaging study of 23 people in Germany looked into the links between brain chemistry, personality and addiction. Healthy volunteers were given a personality test to measure novelty seeking, harm avoidance, reward dependence and persistence. They then underwent a brain scan. Those people with a high reward dependence had a high concentration of opiate receptors in an area of the brain called the ventral striatum which is considered to be very important in the development of addictive behaviour. These people have a relative shortage of endorphins to link up with their opiate receptors and could, therefore, be more likely to turn to illegal substances, or indeed alcohol or tobacco, to make up the deficit.
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