This is an extract from Judith Grisel's Never Enough. Join our World Economic Forum Book Club to discuss this excerpt.

I was twenty-two. I’d been on the good end of a bad drug deal. In the wee hours of some morning late in 1985, behind a nameless restaurant in South Florida, a dealer gave me and a friend the wrong bag. I was the “winner” in this deal with substantially more drug than I was obliged to pass on to a friend of a friend somewhere in the Midwest.

Homeless at the time, my compatriot and I ended up checking into a cheap motel in Deerfield Beach. Predictably, we used the surplus along with what we owed. Toward the end of that binge, the stash mercifully depleted, both of us exhausted and on edge, my friend inexplicably announced that there would never be enough cocaine for us. While the prophecy struck me as true even in my overwhelmed state, I also knew it was irrelevant. As with every addict, my days of actually getting “high” were long past. My using was compulsive and aimed more at escaping reality than at getting off. I’d banged my head against the wall long enough to realize that nothing new was going to happen—except perhaps through the ultimate escape, death, which frankly didn’t seem like that big a deal.

About six months later, through a series of circumstances rather than personal insight or strength of character, I was clean and sober for the first time in years, and therefore not quite so numb. I saw that I had a life-or-death choice. I could continue colluding with my mental illness as it inexorably consumed me, or I could find a different way to live.

In my experience, very few faced with those possibilities choose life, and I first went with the majority. The cost of abstinence seemed too high: Without drugs, what would there be to live for anyway? However, in a demonstration of tenacity almost diagnostic of an active addict, it dawned on me that I might be able to find another way. After all, I thought, I’d come through many tight situations: bad deals in condemned buildings or police stations, with or without loaded guns, and miles from anything friendly or familiar. Aware now for the first time of the medical model of addiction, I figured that my disease was a biological problem that could be solved. I decided to cure addiction so I could somehow eliminate the problems caused by using.

With what may seem like exceptional fortitude to some, especially given that I’d been kicked out of three schools by this time, I went on to get a Ph.D. in behavioral neuroscience and to become an expert in the neurobiology, chemistry, and genetics of addictive behavior. This accomplishment would seem almost unremarkable to most addicts, who know firsthand that there is nothing we would not do, no sacrifice too great, to be able to use. It ultimately took seven years to graduate from college, including about a year of dramatic change starting in a treatment center, plus another seven years of graduate school to earn that degree.

This book is a summary of what I have learned over the past twenty or so years as a researcher studying the neuroscience of addiction. Though I’ve received grants from the National Institutes of Health and possess a controlled-substance license from the Drug Enforcement Administration (DEA), I regret to say that I haven’t solved the problem. I have, however, learned a lot about how people like me differ even before they pick up their first drug and about what addictive substances do to our brains. My hope is that sharing this information might help loved ones, caregivers, and crafters of public policy make more informed choices. Perhaps this understanding may even help the afflicted ones themselves, because it’s quite clear to me that the solution isn’t coming in a pill.

Addiction today is epidemic and catastrophic. If we are not victims ourselves, we all know someone struggling with a merciless compulsion to remodel experience by altering brain function. The personal and social consequences of this widespread and relentless urge are almost too large to grasp. In the United States, about 16 percent of the population twelve and older meet criteria for a substance use disorder, and about a quarter of all deaths are attributed to excessive drug use. Each day, ten thousand people around the globe die as a result of substance abuse. Along this path to the grave is a breathtaking series of losses: of hope, dignity, relationships, money, generativity, family and societal structure, and community resources.

Worldwide, addiction may be the most formidable health problem, affecting about one in every five people over the age of fourteen. In purely financial terms, it costs more than five times as much as AIDS and twice as much as cancer. In the United States, this means that close to 10 percent of all health-care expenditures go toward prevention, diagnosis, and treatment of people suffering from addictive diseases, and the statistics are similarly frightening in most other Western cultures. Despite all this money and effort, successful recovery is no more likely than it was fifty years ago.

There are two primary reasons for the incredibly broad, deep, and persistent costs of drug addiction. First, excessive use is remarkably common, cutting across geographic, economic, ethnic, and gender lines with little variation. It is also highly resistant to treatment. Although reliable estimates are hard to come by, most experts agree that no more than 10 percent of substance abusers can manage to stay clean for any appreciable time. As far as illnesses go, this rate is almost singularly low: one has about twice as good a chance of surviving brain cancer.

Despite a statistically bleak outlook, there are some reasons to be encouraged. Some addicts, once desperate cases, do get clean and stay clean, and even go on to live productive, happy lives. While neuroscience hasn’t been able to thoroughly parse the mechanisms behind this transformation, we have learned quite a lot about the causes of the problem. We know, for instance, that addiction results from a complex web of factors including a genetic predisposition, developmental influences, and environmental input. I say complex because each of these factors is very dense. That is, hundreds of genes and innumerable environmental contributions are involved. The factors also depend on one another. For example, a particular strand of DNA may enhance a liability for addiction but only in the presence (or absence) of other specific genes and along with certain experiences during development (either pre- or postnatal) and in specific contexts. So, while we may know a lot, the complexity of the disease means that we are still unable to predict whether a particular individual will develop an addiction.

While in the end there might be as many different paths to addiction as there are addicts, there are general principles of brain function that underlie all compulsive use. My aim in writing this book is to share these principles and thus shed light on the biological dead end that perpetuates substance use and abuse: namely, that there will never be enough drug, because the brain’s capacity to learn and adapt is basically infinite. What was once a normal state punctuated by periods of high, inexorably transforms to a state of desperation that is only temporarily subdued by drug. Understanding the mechanisms behind every addict’s experience makes it very clear that short of death or long-term sobriety there is no way to quell the screaming need between exposures. At the point where pathology determines behavior, most addicts die trying to satisfy an insatiable drive.

Excerpted from Never Enough by Judith Grisel. Copyright © 2019 by Judith Grisel. Excerpted by permission of Doubleday. All rights reserved.

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