What causes addiction?
The word “addiction” is derived from a Latin term for “enslaved by” or “bound to.” If you have had an addiction then you will understand why.
Addiction exerts a prolonged and powerful influence on the brain that manifests in three distinct ways: Addiction involves an intense craving for something, losing control over how its used, and despite adverse consequences the continued use of it.
Until fairly recently experts believed that only alcohol and powerful drugs could cause addiction. However modern technologies and recent research, have shown that certain pleasurable activities, such as gambling, shopping, and sex, can also be addictive.
Although the American Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition or DSM-IV, describes multiple individual addictions, one for each specific substance or activity, contemporary thought indicates that these may represent different expressions of a common underlying brain process.
New insights into a common problem
When researchers first began to investigate what caused addictive behaviour In the 1930s, It was widely believed that people who developed addictions were morally weak or lacking in willpower.
They thought overcoming addiction, involved punishing the addicts or alternately, encouraging them to use their willpower to break the habit.
Things have changed since then. Today we recognise addiction as a chronic disease that causes change to both the structure and function of the brain. Much like cardiovascular disease damages the heart, diabetes impairs the pancreas, in a similar vein, addiction hijacks the brain. The brain goes through stages of changes, beginning with recognition of pleasure and ending with a driven compulsive behaviour.
Pleasure principle
In the brain, all pleasures are recognised in the same way, regardless if it’s from drugs, monetary rewards, sexual gratification, or simply a satisfying meal. The brain gives pleasure its own distinct signature. This triggers the release of the neurotransmitter dopamine into the nucleus accumbens*. This is a cluster of nerve cells underneath the cerebral cortex. This is so consistently associated with pleasure that it is referred to, as the brain’s pleasure centre.
All abuse of drugs, from nicotine to heroin, cause a powerful surge of dopamine in the nucleus accumbens. The use of a drug or taking part in a rewarding activity that will lead to addiction can be directly linked to the speed that it promotes the dopamine release, along with the intensity and reliability of the release.
Addictive drugs tend to find a shortcut to the brain’s reward system, and then flood the nucleus accumbens with dopamine. The hippocampus remembers this rapid sense of satisfaction, then the amygdala creates a conditioned response to the stimuli.
Learning process
Scientists once believed that just experiencing pleasure was enough to make people continue to seek an addictive substance or indulge in a certain activity. However more recent research indicates that the process is more complicated. Dopamine contributes to the experience of pleasure, but it also plays a part in memory and learning.Two of the key elements in going from liking something to becoming addicted to it.
Dopamine works with another neurotransmitter, glutamate, together they take control of the brain’s system of reward-related learning. This system of reward-related learning has an important role in sustaining life. It links the activities we need for human survival with pleasure and reward. (such as eating and sex)
Continued exposure to an addictive substance or behaviour, will cause nerve cells in the nucleus accumbens along with the prefrontal cortex which is the area of the brain used for planning and executing tasks. Together they communicate in a way that joins the liking of something with the wanting of it. In turn, this drives us to go after it. This process gives us the motivation to take action to find that source of pleasure.
Development of tolerance
With the passing of time, the sought-after substance or activity doesn’t provide as much pleasure as it did initially. The brain has adapted to them, It has developed a tolerance. Usually natures rewards come only with time and effort. In the case of addictions, addictive drugs and behaviours provide a shortcut, the brain is flooded with dopamine and other neurotransmitters.
Whilst engaging with addictive drugs and behaviours, greater amounts than are associated with normal natural rewards, maybe 2 to 10 times the amount of dopamine are being released. These rewards are incredibly quick and reliable.
In someone who has become addicted, their brain receptors become overwhelmed. In response to this, one or both of these things happen, firstly the elimination of dopamine receptors, and secondly, the production of less dopamine. The brain is trying to protect itself, by keeping the amount of dopamine within a normal range.
The result of this, is that the dopamine has less effect on the brain’s reward centre.
Someone who has an addiction typically finds in time, that the desired substance has ceased to give them the same pleasure. They need more to obtain the same “high” because their brains have adapted—an effect known as tolerance.
Compulsion takes over
Once addicted and tolerance has developed, compulsion takes over. The pleasure gained from the addictive drug or behaviour is now harder to come by, but the memory of the pleasure, and the need to recreate it remains, as if the normal process of motivation is no longer working. As we mentioned earlier the learning process also comes into play. The information has been stored in the hippocampus and the amygdala about the environmental cues associated with the desired substance. And in order to locate it again, these cues are accessed. These memories assist in creating a conditioned response, an intense craving, that is triggered whenever the person encounters those environmental cues.
Unfortunately, cravings do not only occur in relation to addiction, but also with relapse after having got free of the addictive drug or behaviour. Because of the “conditioned learning” the sight of a hypodermic needle, or the sight of a whisky bottle may be enough to cause a relapse. This helps to explain why, even after a prolonged period of abstinence relapses occur.