When you are addicted, you no longer have control over your use of substances. For example, you want to stop using them, but you just can’t seem to manage it. You can be addicted to substances such as alcohol and drugs, but also to gambling or gaming, for example. Nowadays, we mainly refer to substance addiction in terms of ‘substance use disorder’, for example ‘alcohol use disorder’. These disorders often develop gradually, which can take months, but often takes years. A substance use disorder develops in three phases, which are described below.
Phase 1: Positive reinforcement phase
The initial period of use is often characterized by the pleasurable effects of the substance. For example, people feel relaxed or, conversely, experience a surge of energy. Virtually all addictive substances affect the reward system in the brain, specifically the dopamine system. Dopamine is an important neurotransmitter that is released during all enjoyable activities in life, such as eating, social contact, and sex. This is what makes these activities rewarding, which is of course important for human survival. However, addictive substances provide a much higher reward after use than these activities. As a result, the brain may subconsciously label substance use as important. Because the brain has come to consider the substance important, people may want to use it more and more often. In addition, just seeing the substance can trigger a craving to use it. This pattern of use is not yet problematic, and for most people, it stops there.
Phase 2: Loss of control phase
In the second phase, the brain becomes less sensitive to the effects of the drug, a phenomenon known as habituation. As a result, people need more of the drug to experience the same effect. In addition, the brain also compensates more for the effects of use. For example, if a drug has a very relaxing effect, the brain will produce more activating substances when it thinks that drugs are coming. This can make people feel somewhat restless when they are not using. People are often unaware or only vaguely aware that this process is taking place. People no longer use drugs just for pleasure, but to feel ‘normal’ for a while. So there is a clear shift in motivation compared to the first phase. The brain needs drugs more often to stay balanced. In this way, drug use can become more part of daily life and routine. In addition, more and more things in life will trigger cravings. Whereas before it might have been the substance itself or the place where you always used it, now it could also be certain emotions, certain objects, or places that your brain has come to associate with the substance. This can lead to more frequent loss of control. You need the substance more and more often to feel normal, and more and more things in life trigger cravings for the substance.
Phase 3: Negative reinforcement phase
The loss of control often only becomes truly apparent in the third phase. Substance use becomes increasingly dominant. As a result, other previously important matters become less important. For example, people go to work less often or are under the influence during work. They start to isolate themselves more and cancel appointments with others more often. There may also be more personal neglect, with people eating less, exercising less, and taking less care of themselves. These are all signs that substance use has become so important that other things have to take a back seat. In addition, substance use has become routine; whereas use was once part of life, it now dominates life. The reward system is preoccupied with use throughout the day and constantly focused on where and how to use. This is partly an unconscious process, but this part of the brain is increasingly gaining the upper hand. The more rational part of the brain, which makes plans for the future, is becoming weaker. As a result, people often resolve not to use drugs, but still fail to do so. This often makes it complicated for people: on the one hand, they no longer want to use drugs (the rational part), but on the other hand, the irrational part (the reward system) has such a strong hold that they automatically use drugs when they are available. Wanting and being able are no longer in balance. In many cases, this causes a lot of shame and self-stigma, which often makes people afraid to ask for help because they are afraid of being rejected. At this stage, use is no longer really enjoyable but increasingly about getting through the day/being able to sleep; use is now mainly about avoiding withdrawal. This is what makes addiction so persistent: reflexive use combined with impaired thinking due to the effects of the substance/sleep problems and the great shame people experience when asking for help.
This blog was written by Harmen Beurmanjer (Radboud University) for RAD-blog, the blog about smoking, alcohol, drugs, and diet.
The above piece is a summary of the articles below:
Compton WM, Wargo EM, Volkow ND. (2022) Neuropsychiatric Model of Addiction Simplified. Psychiatr Clin North Am. 45(3):321-334.
Volkow ND, Koob GF, McLellan AT. (2016) Neurobiologic Advances from the Brain Disease Model of Addiction. N Engl J Med. 374(4):363-71.
A visual animation of this process:
Want to read more about how addiction develops in the brain?
Volkow ND, Michaelides M, Baler R. (2019) The Neuroscience of Drug Reward and Addiction. Physiol Rev. 1;99(4):2115-2140.
Volkow ND, Morales M. (2015) The Brain on Drugs: From Reward to Addiction. Cell.
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