Addiction is described by a strong desire for something, a lack of control over its use, and a willingness to engage in it despite negative consequences. Addiction alters the brain, first by altering how it registers pleasure, then by corrupting other natural drives like learning and motivation. While overcoming an addiction is difficult, it is possible.
The cause of addiction
Addiction has a long and powerful effect on the brain, manifesting itself in three ways: a strong desire for the object of addiction, a lack of control over its use, and a willingness to engage in it despite negative consequences.
For several years, psychologists concluded that addiction could only be caused by alcohol and strong drugs. However, new studies and neuroimaging technologies have shown that such pleasurable behaviors, such as gambling, shopping, and sex, can also co-opt the brain.
Addiction is now recognized as a chronic condition that affects both the structure and function of the brain. Addiction hijacks the brain in the same way as cardiovascular disease harms the heart and diabetes harms the pancreas. This occurs as the brain undergoes a series of changes, starting with pleasure recognition and culminating with a desire to engage in compulsive behaviour.
Pleasure principle
If the gratification comes from a psychoactive substance, a monetary reward, a sexual experience, or a fulfilling meal, the brain records all pleasures in the same way. Pleasure in the brain is marked by the release of the neurotransmitter dopamine in the nucleus accumbens, a group of nerve cells under the cerebral cortex (see illustration). The nucleus accumbens' dopamine release is so closely linked to pleasure that neuroscientists refer to it as the brain's pleasure core.
In the nucleus accumbens, all drugs of abuse, from nicotine to heroin, trigger a particularly strong rush of dopamine. The pace at which a drug or engaging in a rewarding behavior promotes dopamine release, the duration of that release, and the consistency of that release are all factors that influence the risk of addiction.
Also different ways of administering the same medication may have an impact on how likely it is to lead to addiction. Smoking or injecting a drug intravenously, rather than swallowing it like a tablet, provides a quicker, stronger dopamine signal and is more likely to lead to drug abuse.
By loading the nucleus accumbens with dopamine, addictive drugs offer a shortcut to the brain's reward system. The amygdala produces a conditioned reaction to such stimuli, and the hippocampus stores memories of this rapid sense of satisfaction.
Learning process
Scientists used to assume that simply experiencing gratification was enough to motivate people to search out an addictive drug or behavior. Recent research, on the other hand, indicates that the situation is more complicated. Dopamine is involved in not only the sensation of pleasure, but also in learning and memory, all of which are essential in the transformation from like to addiction.
Dopamine combines with another neurotransmitter, glutamate, to take over the brain's reward-related learning mechanism, according to existing addiction theory. Since it connects behaviors necessary for human survival (such as eating and sex) with enjoyment and reward, this mechanism plays an important role in sustaining life.
The reward circuit in the brain is made up of areas that are involved in motivation, memory, and pleasure. Substances and habits that are addictive activate the same circuit, which is then overloaded.
When nerve cells in the nucleus accumbens and the prefrontal cortex (the region of the brain involved in planning and performing tasks) are repeatedly exposed to an addictive drug or action, they interact in a way that pairs enjoying something with wanting it, motivating us to pursue it. This method, in other words, motivates us to take action in order to find the source of pleasure.
Development of Tolerance
The brain adapts over time in such a way that the desired object or action becomes less pleasurable.
In nature, the only way to get something is to put in the time and effort. The brain is flooded with dopamine and other neurotransmitters as a result of addictive substances and habits. Our minds are ill-equipped to deal with the onslaught.
Addictive drugs, for example, can release two to ten times the amount of dopamine that normal rewards can, and they do so faster and more consistently. The brain receptors of an addicted person become overloaded.
When noise becomes too noisy, the brain responds by creating less dopamine or suppressing dopamine receptors, which is equivalent to turning down the volume on a loudspeaker.
Dopamine has less of an effect on the reward center of the brain as a result of these adaptations. People who acquire an addiction typically discover that the desired drug no longer provides them with the same level of satisfaction over time. Since their brains have evolved, they must take more of it to achieve the same dopamine "high." This is known as tolerance.
Compulsions takes over
Compulsion takes over at this stage. The gratification associated with an addictive substance or action fades, but the memory of the desired result, as well as the urge to replicate it (wanting), remains. It's as if the usual motivational machinery has stopped working.
The earlier described learning process also comes into action. The hippocampus and amygdala store knowledge regarding environmental cues correlated with the desired material in order to find it later. When the person is exposed to certain environmental cues, these memories help to establish a conditioned response—intense craving.
Cravings play a role in addiction as well as relapse after a long period of abstinence. When a heroin addict sees a hypodermic needle, for example, he may be in danger of relapsing, whereas another person may begin to drink again after seeing a bottle of whiskey. People who acquire an addiction are more likely to relapse even after years of abstinence, according to conditioned learning.