What does addiction do to your brain?
Addicts’ brains show differences from people who have no addictions. They can include changes in gene expression, in connections within and between parts of the brain, and in levels of neurotransmitters and their receptors – especially the key reward chemical, dopamine.
At a higher level, there can also be differences in perception and information processing.
These differences can be generated as addiction develops. Sometimes, they may have been there all along. So addiction does change the brain, but some people’s brains predispose them to get addicted in the first place.
The brain–addiction link is reinforced by evidence that some kinds of brain damage can help to reduce addictions. The insula (which works directly with the limbic system) is a small part of the cerebral cortex involved in feeling and emotion. A high percentage of cigarette smokers who suffer brain damage from a stroke find it easy to give up if the damage involves the insula. They lose their craving for nicotine, although their appetite for food and drink remains normal. Experiments with rats whose brains are partially anaesthetised have shown a similar effect for amphetamine.
More dramatic are reports that Russian and Chinese surgeons performed surgery to ‘cure’ heroin addiction in hundreds of patients, using electrodes to destroy certain parts of the brain. Experts elsewhere say the published results of these procedures are incomplete. Other treatments are equally effective, they argue, and there are doubts about the safety of the procedures, and whether addicts consented to the operations. The Russian and Chinese governments have now banned this treatment.