The United States has the leading number of deaths from overdoses, but addiction is not just an American problem (Lopez, 2017). According to the 2017 World Drug Report, nearly 30 million people worldwide suffer from substance abuse disorders (United Nations, n.d.). Many of these addicts struggle with more than one disorder at the same time, including multiple addictions or mental illness diagnosis (Statistics, n.d.).

Addiction is nothing new, but there is disagreement on what causes it. It is a complicated problem influenced by many factors, including poverty, genetics, and environments. One of the greatest struggles that come from this disagreement is how we should treat addiction.

Much of the controversy over addiction comes from differing definitions of what disease is. Scientists and researchers also interpret data about addiction differently and come up with various conclusions. There are currently three main models or ways of looking at addiction:

  1. addiction is a disease
  2. addiction is behavior and habits that are learned
  3. addiction is a choice.

Before we discuss the arguments used in these three models, let us talk about what we know happens in an addicted brain. Next, we will cover why there can be confusion when we label addiction a disease. Finally, we will summarize the three models of addiction and why there is disagreement surrounding them.

The Addicted Brain

At a fundamental level, there are three main parts of the brain involved in addiction. These include the prefrontal cortex, striatum, and midbrain. The prefrontal cortex is located in front of your brain. It helps you plan and make the right decisions. The striatum is located in the very middle of the brain and is responsible for motivation and goal setting. Finally, the midbrain lies just beneath the striatum and influences how we respond to events or situations.

Addictive behaviors seem to be part of a process that evolved into the human brain. When a person’s brain is stimulated by something pleasurable, maybe an image or the smell of a favorite food, the midbrain sends a rush of dopamine (a pleasure-inducing chemical) to the striatum. When this dose of dopamine triggers the striatum, it causes the person to start craving what they were thinking. The more the person thinks about the craving, the more dopamine is released.

The same happens with addiction, only at a deeper level. The striatum and midbrain in an addict have solid connections when a pleasurable trigger occurs, at the expense of the prefrontal cortex. So, when addicts are craving a drug or alcohol, they lose their capacity to think clearly and make the best decisions possible. Their good judgment gets hijacked by unconscious cues and craving mechanisms in their brains (Satel & Lilienfeld, 2014).

These triggering events and cravings create a feedback loop in the brain. An addict experiences something that makes them crave their addiction. Even if they try to ignore it, the desires become stronger and stronger. Finally, the addict is compelled to use and feels satisfied for a time. However, it is just a matter of time before they have another triggering event that starts the craving cycle all over again (TedMed, 2016).

Different drugs affect the brain in unique ways, but they all generally work off of this loop that pushes them to act on cravings. A person may choose to use alcohol or drugs voluntarily at first. But, over time, the changes in the brain can decrease that person’s ability to resist future cravings. Free choice gradually becomes a compulsion to use.

Learning Model of Addiction

Marc Lewis, a developmental psychologist, neuroscientist, and former addict himself strongly argues that addiction is not an actual disease. He agrees that the scientific data and brain scans are precise that changes do occur in the brain during addiction. However, he suggests that there are multiple ways to interpret the results. In Lewis’ opinion, addiction is a matter of deep learning and habit formation (TedMed, 2016).

According to his theory, the feedback loop mentioned earlier causes people to develop strong habits. This happens through three things: 1) a person uses a drug or alcohol because of cravings, 2) the person feels relief and maybe pleasurable feelings as well, and 3) the person feels a sense of loss, shame or guilt. The brain learns that using the substance can help them avoid those bad feelings, and so it presents more cravings, and the cycle repeats itself. With every turn of this cycle, the habit becomes stronger and harder to overcome (Lewis, 2016).

But Lewis does not think this habit formation is a disease. He points out that the brain always changes when learning something, no matter what it is. The brain regularly adjusts its circuits (tracks) as needed. The brain then is not broken or malfunctioning; it is just doing what it was designed to do. This has been shown through brain scans of people who practice meditation, or receive psychotherapy, or even drive taxis for a living and need to remember places and locations with quick recall (Lewis, 2016).

Even though he considers addiction a matter of deep learning and habit formation, Lewis does not make light of addiction. In a 2015 interview in The Guardian, he said he believes that addiction is a socioeconomic problem combined with a “lack of care by the larger society for people who are suffering.” He recognizes that there is a lot of hard work required for addicts to become free from their addictions.

Furthermore, when people are ready to leave their addictions, they need outside support and resources to help them get their feet underneath them once again (Davey, 2015).

Choice Model of Addiction

Boston College and Harvard researcher Gene Heyman offer a third way of looking at addiction: addiction as a voluntary choice. He argues there is only a small percentage of people in the overall population that become addicted. He also points out that approximately 75-80% of all addicts eventually kick their addictions by age 30. This usually happens because they develop goals that are more important to them than the desire to use, including legal or money concerns or the desire to be respected by family and friends.

Heyman does not consider addiction a disease, but neither does he reduce it to a “simple” choice based on the addict’s morals or character. Instead, he describes it as a voluntary behavior that is influenced by life circumstances. It is also related to humans’ tendency sometimes to make dumb decisions or poor choices. If this were not true, he says, the self-help industry in this country would not be thriving like it is, where vast portions of the population are searching for ways to kick procrastination and other bad habits.

Heyman is convinced that the brain disease model of addiction does not hold up when it comes to proper research or logic, for several reasons. First, he points out that the brain scans used to “prove” addiction is a disease is limited and only suggest that brain changes are present with drug use. They do not prove that the drugs caused the changes. If most addicts quit on their own, logic follows that brain changes caused by drugs and alcohol are not enough to prevent changing their long term behaviors. Finally, Heyman says that the addicts in much of the research does not represent all addicts as a whole. Instead, the study is based on a unique group he calls a “distinct minority.” These are the only the addicts that come to the clinic for help, or who are not likely to quit using because of other complicating factors (Heyman, 2013).

Why the Models of Addiction Matter

Some may wonder why these models for understanding addiction are even that important. In reality, how we understand addiction influences treatment strategies and how society views addicts. The development of these models of addiction over time has helped educate people that addiction is not the result of weak character or bad morals.

Each of these models has brought essential ideas to the table that color a broader picture of addiction. They help to continue thoughtful dialogue and debate between different branches of science. Instead of giving us simple reasons for addiction, each model discussed above admits that addiction is complex and requires hard work to overcome.

The models also seem to agree that initially, many drug and alcohol addictions begin with a voluntary choice to use a substance. However, why do people choose to use and what happens in the body afterward are both sources of disagreement. The brain science is precise, but there is no clear consensus on what the data tells us about addiction.

Finally, although everyone no longer accepts the conventional brain disease model of addiction, it has attracted funding for brain imaging, genetics research, and drug development studies. Data from this brain research will no doubt be helpful in other areas of disease beyond addiction.


We must not reduce addiction to morality, character, or chemical imbalances. No matter what model we support, we must acknowledge that addiction is a complex issue that has over reaching effects into all areas of society. Each of the models presented may disagree on the causes of addiction, but they each contribute to the conversation and lay the groundwork for improved addiction therapies and treatments in the future.