Addiction is Not a Brain Disease
The dominant model in the medical community has done more harm than good.
Recently, I gave a talk to a group of neurobiologists in honor of a former friend and colleague, Robin Lester, who tragically died too young. Robin let me attend his class, provocatively titled “No Self-Control: The Neuroscience of Addiction.” He welcomed my presence based solely on a cold message (sent to his university email address, which was simply “nicotine”). Later he would give a guest lecture on the topic for my Neuroethics class. Robin was a neuroscientist, but he loved philosophical discussions. Mostly we disagreed about whether addiction is a brain disease.
Before attending Robin’s class, I knew most scientists and clinicians view addiction as a disease. There seemed to be plenty of research backing up this theory, so I was already a believer. Imagine my surprise when I later came to reject it. (Does this make me a good student or a bad one?)
Our scientific grasp on addiction really matters. The brain disease model gained prominence in the 1990s, yet overdoses have continued to rise, which is just one among many ways dependence can devastate families and communities. Any hope of reversing such trends requires a sound understanding of the causes of addiction— and not just to illicit drugs and prescription opioids, but to alcohol and other legal substances that get abused.
So what is this brain disease model? It’s not merely the view that addiction involves the brain. No one disagrees with that. Even dualists like Descartes recognize that the brain is involved in all thoughts, feelings, and desires.
Rather, the National Institute on Drug Abuse goes further, saying that addiction is “a lot like other diseases such as heart disease,” as both “disrupt the normal, healthy functioning of an organ in the body.” Addiction is just different in being a “chronic, relapsing disorder characterized by compulsive drug seeking and use despite adverse consequences.”
There are three key pillars of this brain disease view:
Addiction is a disease, involving bodily dysfunction.
The dysfunction is in brain circuits caused by ingestion of substances of abuse (this is important).
The dysfunction leads to compulsive use (a loss of self-control), due to irresistible desires.
I was surprised to find thick cracks in each of these pillars.
Compulsion?
After stealing some jewelry to pay for drugs, Julie Eldred was ordered by a judge to stay clean during her probation—or else face jail time. When she tested positive for fentanyl, her legal defense argued that she “did not ‘choose’ to relapse any more than a person who has hypertension chooses to have high blood pressure.” The argument didn’t ultimately sway the Massachusetts Supreme Court.
In some cases, cravings may be too powerful to overcome. Yet ample research shows that people with severe drug dependance can deliberately abstain. Sometimes they seek to avoid punishment—such as losing a good job or a marriage—while others are driven by the rewards of a successful career or being a model parent. Researchers have even found that addicts will regularly turn down a free hit of their drug of choice for modest amounts of cash. The abstention may be temporary, but if cravings are irresistible, this should be impossible or exceedingly rare.
Much of that research was carried out by Carl Hart, a neuroscientist at Columbia University. As recounted in his memoir, High Price (2013), Hart grew up in the projects of Miami and wanted to discover the neurobiological key to combatting the addictions that plagued his community. He grew deeply disappointed with the brain disease model and was shocked to find that using drugs doesn’t typically lead to compulsive use. (In his latest book, Drug Use for Grown-Ups, Hart argues forcefully that responsible drug use is possible, citing his own recreational heroin use as one example.)
Both research and stories of successful recovery suggest that compulsion isn’t always the case. Even so, surely it’s still a brain disease, right? That’s what I thought.
Brain Dysfunction?
Does addiction primarily arise from ingestion of drugs (or alcohol) that cause dysfunctional brain circuits? Well, contrary to what I was told as a kid, the vast majority of people don’t get addicted after using drugs. (Still, kids, say no to drugs.) The people most prone to addiction after using are those who experience trauma, depression, anxiety, or impulsivity due to personality disorders. All of these involve the brain, to be sure. (Where else would anxiety and depression be? Your knee caps?) But these are pre-existing conditions that arguably contribute more to addiction than the ingestion of drugs.
A classic illustration is the famous “rat park” study. Around the 1970s, neuroscientists found that rats would often get addicted to water laced with morphine when it’s offered in addition to plain old tap water. It’s as though ingesting the drugs caused a change in the rats’ brains, making them want more and more. The seeds of the brain disease model were sown.
But then some researchers thought, well, rats are social creatures, like many other mammals. Maybe they’re driven to drugs because they’re stuck alone in a cage in a boring laboratory. So Bruce Alexander and his team performed the same sorts of studies but put some rats in “enriched” cages, where they could socialize and play. Drug use went down. (Apparently, one attempt to replicate Alexander’s classic study failed, but the consensus seems to be that enriched environments do minimize drug use.)
Similar results can be found in humans. During the Vietnam war, the amount of heroin use among American soldiers overseas was alarming. The U.S. government commissioned a study of vets as they returned home. Surprisingly, they found that most didn’t have an addiction problem when they returned. It’s not that heroin wasn't available; it was. The difference was that heroin became less tempting back home, further from the circumstances of war.
There’s no doubt that stress from combat or isolation manifests in the brain. But, again, the primary cause of addiction doesn’t seem to be ingestion of drugs, but ingestion of drugs under certain conditions. It looks as though you can reduce addiction rates by changing the environment.
Same goes for pre-existing mental disorders. Even if one is genetically predisposed to, say, anxiety and depression, which occur in the brain, the source of the addiction isn’t primarily the ingestion of drugs but these distinct mental disorders.
While addiction certainly has something to do with the ingestion of drugs, is that enough to call it a brain disease? Addiction, it seems, has a lot more to do with poverty, trauma, and other factors besides drug consumption. Poverty also generates stress which is manifested in brain activity, but calling poverty a brain disease would be perverse.
Disease?
Now, even if addiction isn’t primarily dysfunction in brain circuits due to ingestion of drugs, surely it’s some sort of bodily dysfunction. That may be right, and I do believe we should consider addition a disorder, as currently captured by “substance use disorder” in the DSM (the Diagnostic and Statistical Manual of Mental Disorders).
Proponents of the brain disease model typically agree that addiction is a kind of substance use disorder, just an extreme form of it. Yet that courts confusion, since “addiction” in ordinary discourse includes milder forms, and we do a disservice by excluding those cases from this important category of research and treatment.
At any rate, notice how far we’ve departed from the brain disease model. No longer is addiction like heart disease. It’s more like depression, a mental disorder. There is a neurobiological basis, but it’s quite unlike a discreet pathology in the brain, like Parkinson’s or Alzheimer’s diseases.
Indeed, the underlying brain mechanisms in addiction aren’t necessarily damaged or dysfunctional. After long-term drug use, the reward center of the brain does exhibit changes. The mesolimbic dopamine pathway becomes hyperactive (though not necessarily “hijacked”) in response to seeing or thinking about drugs and drug paraphernalia. Yet, as Marc Lewis says, this could be seen as a normal mechanism (reward learning) operating in response to very powerful rewards.
A prominent addiction researcher, Kent Berridge, replies that addiction is different in kind from ordinary reward learning, not just different in degree. Sure, cravings are just the reward center going into overdrive, but that’s like the difference between being just hungry and literally starving.
We should take seriously how powerful and abnormal cravings can be. And yet our present question is whether addiction is best thought of as a disease, and the comparison to starvation suggests otherwise. While starvation is very, very different from mild hunger, it’s not a disease or even bodily dysfunction. Starvation is the body doing what it’s supposed to do in extreme circumstances. Addiction might be similar.
To be clear, the disease pillar of the brain disease model is probably the most solid of the three. Addiction does involve some sort of bodily dysfunction, even if it’s not primarily due to ingestion of drugs. That dysfunction might be primarily a matter of trauma, stress, depression, anxiety, or all of the above. It just doesn't look like the brain disease model.
Disorder
Even if the brain disease model lacks support, shouldn’t we still champion the brain disease label? Calling addiction a “disease” might reduce stigma and help addicts receive the support they need.
However, as Hanna Pickard has pointed out, it’s not even clear that the label helps achieve those noble goals. Calling something a “disease” doesn’t necessarily destigmatize it (think AIDs and leprosy). And the brain disease model risks disempowering addicts who are told that they lack control over a broken brain. That may be just what some people need, but many addicts benefit from being empowered to take the reins and change their fate—even if that just means seeking support and following through with treatment. Recovery requires many choices that only patients can make.
It’s tempting to think that if we abandon the disease label, we’ll be back to the old harmful view that addiction is a moral failing. But that’s a false dichotomy. The middle path is to view addiction as a disorder, one that’s caused primarily by trauma, stress, anxiety, depression, impulsivity, and many other factors besides the ingestion of drugs. And it’s a disorder over which addicts can—even if not always—exert control.
I never did convince Robin to fully abandon the brain disease model, but I’m just grateful to have learned from him and to have the debate.
Note: This essay draws on ideas from Chapter 5 of my book, Neuroethics, which contains many more references to the relevant literature.
There is such a thing as chemical dependency, but that isn't the same as addiction. Chemical dependency is when physiology adapts to the presence of a chemical, such that removal leads to withdrawal. Straight-forward, painful, sometimes fatal.
Addiction is when there is an appetite - a need - for something that is imperfectly met by an available or more readily accessible substitute; such that the substitute appears to meet the need. By sensing that the need is filled when it actually deepens, the pursuit of the substitute intensifies and deepens, even while the void or hunger grows. The substitute can be good by itself, but it isn't meeting the need that prompts the pursuit. Thus a cycle of addiction - self-destructive behavior.
As a result, one could be addicted to work as a substitute for community, fiction for friendship, or food for sleep, ...
Addiction is just hyper-rationality -- what Parfit and Sidgwick would have called "present-aim egoism" -- the idea of trying to maximize wellbeing at each moment instead of across one's whole life. I suppose you could call it a brain disease, but it's a brain disease only in the sense in which too much rationality is a brain disease :).