Our Brains Are Designed for Addiction — and That's Not Necessarily a Bad Thing

Addiction may be a frightful and insidious process of change in our habits, but that doesn’t make it a disease.

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The following is an excerpt from  The Biology of Desire: Why Addiction Is Not a Disease by Marc Lewis PhD (PublicAffairs, 2015): 

What’s it like to be a brain? It’s nothing like being a person. We carry our brains around with the rest of our bodies because we’d be lost without them, but brains are only parts of people. And we have many other parts with many diverse functions. So when we say my brain made me do it, or my brain hurts, or my brain really likes alcohol, we are mixing metaphors, confusing levels of analysis. Similarly, to state that craving or pleasure takes place in a certain part of the brain is a figure of speech. The so-called reward centre is actually a conglomerate of remarkably distinct cell assemblies. The fact that these cell assemblies become activated by the scent of an upcoming binge does not mean that a reward bell chimes pleasantly in that location. Brains don’t have likes or dislikes, rewards or punishments, goals or cravings. Those are things people have. And brain cells don’t contain thoughts or feelings. What they contain are membranes, molecules, proteins, blood, and constantly fluctuating levels of electricity. We crave, we have feelings, and we get addicted.

Brains just do what hundreds of millions of years of evolution have determined to be useful, and that includes identifying things that taste good or feel good to us. The brain distinguishes those things from everything else—the background music of the humdrum world—and propels us to go after them. Psychologists call those things “rewards,” things like ripe peaches, fresh bread, orgasms, and even cuddles, and, by association, money, good looks, and power. Oh, and drugs. Addiction may be the uncanny result of a brain doing exactly what it’s supposed to do.

Brains are nothing like digital computers either. We often compare the brain to a digital computer, because it’s pretty good at solving logical problems. But the computer model of the brain died a natural death in cognitive science at least twenty years ago. From the early 1990s onward, cognitive scientists and neuroscientists began to describe the brain as “embodied” and to see its functions in biological terms. Around the same time, computer scientists began to put away their “artificial intelligence” machines and replace them with “neural networks”—which work completely differently. These models at least approximate the network-like quality of real brains, whose cells are connected more like ivy leaves than like boxes and arrows. And, all the better for realism, these models make mistakes!

I remember when I first learned how easily neural networks make mistakes. Three descriptor terms were fed into the network model as “input.” Our task, as grad students, was to come up with a quick answer to the question “Who are we talking about?” and then compare that answer to the “output” provided by the network. The three terms were “movie star,” “politician,” and “intelligent” and the answer that came to everyone’s lips was “Ronald Reagan.” The network spat out the same answer. “But you see,” our typically left-leaning professor said with a grin, “one-third of the information is false!” It pays to remember that brains make decisions based on biased, convoluted, and often just-plain-mistaken input.

Daniel Kahneman’s bestselling book Thinking, Fast and Slow summarizes thirty years of progress through which psychologists (and students of behavioural economics) have come to recognize how biased and irrational our thinking can be. None of this should be very surprising. After all, the brain is a body part whose concern is the slaking of desires and avoidance of risk, goals carried out by hand, tongue, teeth, feet, and genitals. Rationality is a useful tool for planning our route in rush-hour traffic, for dinner-table debates, and for getting A’s in school. But it’s not the front-runner when it comes to eating, sex, pain, pain relief, self-fulfillment, looking cool, and US elections.

So to say that addiction isn’t rational is just stating the obvious. The irrationality (including self-destructiveness) of addiction does not indicate that the brain is malfunctioning, as it would if diseased. It just shows that it’s a human brain. Thinkers from Homer to Dennett and writers from Shakespeare to Nabokov have made it abundantly clear that irrationality is an essential feature of being human.

Warning: May Be Habit Forming

The word “neuroplasticity” is on everyone’s lips these days. The term simply describes brain changeability and elevates it to a first principle. Which makes sense: there’s nothing more fundamental to the human brain than changeability. Yet neuroscientists who study addiction seem to have missed the point. They put people through a number of brain scans, and when they notice changes after someone has taken a lot of cocaine or drunk a lot of booze, they say, “Look! The brain has changed!” If neuroplasticity is the rule, not the exception, then they’re actually not saying much at all. The brain is supposed to change with new experiences. In fact, the newer, more attractive, and more engaging something is, the more likely the brain is to change, and the more likely those changes are to condense into habits—an outcome of more frequent repetitions.

People have referred to addiction as a habit throughout recent history. That’s just what it is. It’s a nasty, often relentless habit. A serious habit. An expensive habit. But what makes it so enduring, so relentless, so difficult to change? What makes it different from what we might call more benign habits? Three things. First, it’s a habit of thinking and feeling—a mental habit—not just a behavioural habit. It’s easier to stop singing in the shower than it is to stop seeing the world as violent or unfair. Second, the feeling part of addiction always includes the feeling of desire, which is of course the theme of this book. And third, it’s a habit that becomes compulsive. Perhaps all habits, once formed, are compulsive to some degree. The brain is certainly built to make any action, repeated enough times, into a compulsion. But the emotional heart of addiction—in a word, desire—makes compulsion inevitable, because unslaked desire is the springboard to repetition, and repetition is the key to compulsion.

Like all habits, addiction quite simply grows and stabilizes, in brain tissue that is designed (by evolution) to change and stabilize. Yet addiction belongs to a subset of habits: those that are most difficult to extinguish. To understand addiction, we need to see it as the outcome of a normally functioning brain, not a diseased brain. Still, we must acknowledge that it’s an extreme outcome, and that’s what has to be explained.

It All Comes Down To Feedback

Exactly how do brains develop? And how do they develop habits? Development is not a simple concept. Plants grow, and so do brains, ecosystems, corporations, and climate patterns. But plants grow along the lines their genes have dictated. Cells divide and follow instructions, so oak trees and tulips look very much like their parents. In contrast, human brains, ecosystems, corporations, and climate patterns grow unpredictably, filling the world with enormous diversity. They create their own fate rather than fall into a fate that’s already set out. They grow, not just by following prespecified guidelines, but by a process known as self-organization. They organize themselves, changing their own structure as they go. As described earlier in this chapter, the patterns we find in brains (and communities, and the weather) are self-perpetuating, building on themselves over time. They change course without much notice (though we might argue that climate change is giving us plenty of notice), and then they continue to grow in that direction. And then they stop changing, or at least they settle and change a lot less. Like the ruts and rivulets formed by rainwater in the garden, they start off unpredictable, but they create and consolidate their own “fate” as they grow. They stabilize. They form habits.

What causes this kind of growth? The answer, surprisingly, lies in the bountiful heart of the feedback loop itself. Feedback loops are just about the most powerful thing in the world. For example, feedback between increasing energy production and increasing energy demand is what causes climate change. Cancer is a nasty feedback loop between increasing cell growth and decreasing inter-cell signalling. When Jimi Hendrix got his guitar pickup (an input system) close to his amp (an output system) he set up a feedback loop, enabling him to create sounds guitars don’t usually make. In my attempts to reach my listeners, auditory feedback has generally been a nuisance. Instead of a new art form, I get a loud hum and a roomful of irritated students. Feedback simply makes things grow. It doesn’t care what.

Back to the brain. The feedback loop I mentioned, between the experience of desire (or other strong emotions) and ongoing changes in brain structure, is one of the prime engines of neural self-organization, or human development in general. If you bite into a piece of chocolate cheesecake and feel a gush of pleasure, and if you’re left with a lingering desire (which surfaces the next time you eat out), you have begun a trajectory of “loving chocolate cheesecake.” At first, maybe just a few synapses have been altered by such an experience. But those changes increase the chance that you will encounter chocolate cheesecake on a future occasion. You will notice it more, acquire it more, and eat it more. And before long a string of subjective experiences will give rise to a string of neural changes that continue to feed back to the ever more predictable consumption of chocolate cheesecake. Congratulations: you have now developed a habit.

It’s crucial to remember that it’s not just attraction or desire that fuels feedback loops and promotes neural habits. Depression and anxiety also develop through feedback. The more you think negative thoughts or scary thoughts, the more synapses get strung together to generate scenarios involving loneliness or danger. Who else might not like you? Did you really think you were going to get away with that? Or generate strategies—often unconsciously—for dealing with those scenarios. I’ll have to be extra nice if I don’t want to be rejected. The result is the sculpting of neural flesh into a breeding ground of personal habits. And one way to capture the combination of those habits is with the word “personality.” Which means I could summarize who you are, in the simplest terms, by listing your most distinct habits, especially those evoked by negative emotions. Isn’t that what we do when someone asks us, “What’s he or she like?”

Neural patterns forged by desire can certainly complement and merge with those born of depression or anxiety. In fact, that’s an important bridge to the self-medication model of addiction. In his 2010 book, In the Realm of Hungry Ghosts, Gabor Maté persuasively shows how early emotional disturbances steer us toward the relief that becomes addiction. So when we examine the correlation between addiction and depression (or anxiety), we should recognize that addiction is often a partner or even an extension of a developmental pattern already set in motion, not simply a newcomer who happened to show up one day.

Different experiential feedback loops create different parts of us, based on different brain patterns, like the work of a painter who does one section of a painting, then another, then another, then goes back and works some more on the first. Of course it wouldn’t be a very good painting if those parts didn’t hold together with some degree of coherence, and the painter knows this very well. When it comes to human development, we don’t necessarily believe that there’s a painter in charge. But there is still a lot of coherence in the end result, and that coherence is often what we call personality. Being this sort of person or that sort of person simply requires a few different feedback loops evolving together, in leapfrog jumps or in continuous collusion. Some of these feedback loops are powered by attraction (like the tendency to be generous because you’re in love) and some by anxiety (like the submissiveness motivated by fear of rejection). These feedback loops work together. They support each other, like a couple of drunks.

So repeated experiences establish patterns, forming habits, and those habits link with other habits that also evolve with repeated experiences. And though developmental outcomes are unpredictable at first, we can predict that whatever, or whoever, emerges will endure and solidify as time goes by—a finished (at least partly finished) human product. Much like a painting. When you gaze upon your one-year-old child, you won’t be able to guess what kind of person he or she will become. But you can rest assured that this person will have a distinct personality. When you gaze upon your thirteen-year-old entering high school, you won’t be able to guess what kind of young adult will come out four years later. But you can bet that he or she will be pretty much a certain kind of person (even if that includes being mixed up) and the same kind of person from one day to the next. Let’s hope it’s a kind of person you like.

Now here’s the point when it comes to addiction. If everything I just described is more or less correct, if this is how humans develop, how they form, then you don’t need an external cause like “disease” to explain the growth of bad habits, or even a set of interlocking bad habits (like being a drug addict and a criminal and a liar). Bad habits self-organize like any other habits. Bad habits like addiction grow more deeply and often more quickly than other bad habits, because they result from feedback fuelled by intense desire, and because they crowd out the availability or appeal of alternative pursuits. But they are still, fundamentally, habits—habits of thinking, feeling, and acting. The brain continues to shape itself with each repeat of the addictive experience, until the addictive habit converges with other habits lodged within one’s personality. Take, for example, the habit of anticipating trouble, feeling anxious, and searching for relief. New habits may spring up around it: you may find you don’t have a lot of friends left, and you’re not on good terms with your mom and dad, because you’ve become consistently snarly or distant. And if you ended up lying to your girlfriend about what you were doing all evening, that will probably develop into a habit as well.

One reason the end result is so coherent is that the social habits that accompany addiction, like lying to yourself and others, mesh so very easily with the self-soothing (or self-feeding) habits that make up the addiction itself. Habits fuelled by anxiety and shame continue to evolve with habits fuelled by desire, because addiction is a risky business. Addicts take big chances, hide the distasteful things they do, and hope for the best. In that respect, addiction can be seen as an extension of personality development. And it can surely be seen as self-medication, but the anxiety and shame that have to be medicated result more and more from the addiction itself.

It's Not Unusual

To say that addiction changes the brain is really just saying that some powerful experience, probably occurring over and over, forges new synaptic configurations that settle into habits. And these new synaptic configurations arise from the pattern of cell firing on each occasion. In other words, repeated (motivating) experiences produce brain changes that start to define future experiences—at least those in the same realm. So getting drunk a lot will sculpt the synapses that determine future drinking patterns. Whether it’s sacramental wine or beer at the ball game, it’ll soon become part of the same familiar drama, if it isn’t already. (It probably won’t affect how you feel about your grandmother or play with your dog—though it might.) These changes don’t result from addictive substances. They are not caused by booze or drugs. They result from having a string of similar experiences. Nice experiences. Experiences of relief. Experiences that feel good, or at least better than the rest of your boring and depressing life. These brain changes are caused by motivated repetition—repetition of something special—and how the brain responds to it. The powerful experiences that get the ball rolling are simply events that affect us deeply. Because they are engaging. Because they mean something. As they become even more meaningful, the corresponding brain changes gather more momentum, building on themselves, digging their own ruts—rainwater in the garden.

Experiences that change the brain most rapidly or extensively might involve drugs or alcohol, and it’s no accident that those substances can be highly addicting. Alcohol and heroin would certainly be less addictive (and a lot cheaper) if they led to experiences that are boring. But high-powered brain-changing experiences also include gambling, binge eating, having a lot of sex, sitting back and watching other people have a lot of sex . . . or simply falling in love. There is nothing more stimulating, salient, attractive, and compelling than the face (and body) of your first high school crush. How many times a day did that person register on your consciousness?

***

That’s enough neuroscience for now. It’s enough to understand the basic features of brain change, how brain change leads to the formation of habits, how recurrent experiences continue to sculpt synaptic networks that continue to pull for similar experiences, and how motivation boosts each step of this developmental sequence. In the case of bad habits, habits that are most difficult to break, alterations in brain flesh have nothing to do with rationality, though they may be guided or misguided by the things you say to yourself in your most rational voice. And they happen regardless of the specific content of the experience, the flavour of the reward you’re after (e.g., sex, drugs, rock and roll). They take place through changes in the way brain cells connect to each other, by the strengthening of some synapses and the weakening of others. They take place in many brain areas, which means that single habits can be quite complex, integrating thoughts, feelings, and behaviour patterns. And addictive habits tend to couple with other habits, simply because they work well together.

The last thing to say is that the same basic mechanism of habit formation—change and stabilization of synaptic networks—works differently in different parts of the brain. For example, the emotional side of habit formation emerges from changes in the amygdala and its close ally the orbitofrontal cortex; new action patterns take root in the motor regions, including regions that organize actions and those that execute them; new habits of thinking are centred in changes in the upper regions of the prefrontal cortex; and new sources of attraction and desire—which are obviously central for addiction—derive from changes in the striatum and its neighbours. These different regions, and their specialized functions, will be highlighted one by one over the next five chapters. I’ll talk about what these brain regions do and how they grow new patterns, to help make sense of the lives of the people you will meet—when they became addicted and when they began to recover. And I think you’ll see that the brain changes that underlie addiction and recovery are more normal than abnormal, though their outcomes can be extreme. Addiction may be a frightful, devastating, and insidious process of change in our habits and our synaptic patterning. But that doesn’t make it a disease.

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Marc Lewis is a neuroscientist and recently retired professor of developmental psychology, at the University of Toronto from 1989 to 2010, and at Radboud University in the Netherlands from 2010 to 2016. His latest book is The Biology of Desire: Why Addiction is Not a Disease (2015-16). He lives in the Netherlands.