As a child growing up in one of Miami's roughest neighborhoods during the 1970s, Carl Hart saw first-hand the toll that poverty, drugs, guns and domestic violence took on his close family and friends. When he was 6, his mother separated from his abusive father. At age 12, he saw his sister injured in a drive-by shooting. Many of his childhood friends ended up dead or in prison. As a teen he used drugs, shoplifted and occasionally carried a gun himself. But eventually — through hard work, mentors, the military and education — he launched himself to the highest rungs of academia.

Hart, who earned his PhD in 1996 from the University of Wyoming, is now Columbia University's first tenured African-American professor in the sciences, where he studies the neuroscience of drug use. Some of his work undercuts widespread assumptions about drug users, such as the idea that most will become addicted. In laboratory studies with cocaine and methamphetamine users, he's found that rather than being held hostage to their drug use, most people can make a rational decision to give up a dose in exchange for a reasonable reward — even as little as $5.

Recently, Hart has become involved in drug policy advocacy as well. In his book "High Price: A Neuroscientist's Journey of Self-Discovery That Challenges Everything You Know About Drugs and Society," he interweaves personal memoir and scientific research to conclude that drug abuse is a symptom rather than a cause of societal ills — and that America's drug laws, not drugs themselves, have wreaked the greatest havoc on the country's poorest and most vulnerable citizens.

Hart spoke to the Monitor about his research and his book.

You've said that "this is not a book about drug addiction." Why is that such an important distinction to make?

There are a broad range of issues that we don't even get into in science because we're trapped in this addiction narrative.

As scientists, we want to have a comprehensive understanding of whatever it is that we're interested in. But one trap that we get into in drug abuse science is that we look at the effects of drugs — on animals, people, the brain, whatever — from a very narrow perspective, the pathology of drug addiction. But that's just a small portion of the effects that drugs have.

So the book includes a little bit about drug addiction, but that's not the most important aspect of drugs in our society. I wanted the book to be about what drugs actually do, what they don't do, the political meaning of drug policy in this country and who's being really deleteriously impacted.

Let's start with "what do drugs actually do?" Your studies have given some answers to that question that some people have found surprising.

The most important finding that I and others have discovered is that drug effects are predictable. We hear people say, "This drug is unpredictable," but they don't have any evidence to support that. When you look at the overwhelming amount of evidence related to the drugs that we're all interested in — methamphetamine, crack cocaine, heroin, marijuana, you name it — all of these drugs produce predictable effects. As you increase the dose, you can expect to get more toxic effects. That's so important for the general public to know. That's so important for young people who may experiment with drugs. And that kind of information isn't shared as freely as I wish it would be. That's one thing.

If you're looking at individual drug effects — like what do amphetamines do — one of the most interesting findings is that they increase your alertness. They produce euphoria, they decrease food intake. All of these kinds of things are important for people to know.

Cocaine can do the same sort of thing, but not as well as amphetamines because of the short half-life relative to the amphetamines. Heroin and opioids are really good at decreasing pain, decreasing anxiety and increasing sleep. They also cause constipation, and in some people cause itchiness.

All of these things are important for [psychologists] to know because it enhances our credibility with drug users — we're not only emphasizing the potential negative effects, but we understand the positive effects as well. People who take drugs by and large are not stupid. They take them for some of these effects that we are describing, not for the addictive effects that we focus on.

Another important point is that most people who take drugs don't meet criteria for addiction. So if you're only focusing on those limited effects related to pathology and addiction, you have alienated the vast majority of drug users.

Some of your studies that have gotten the most attention are those that show that people who use cocaine and methamphetamine react in a logical way if you give them the choice between the drug and a reward. Can you talk about that?

The bottom line is that if you present people who meet criteria for addiction with a choice between the drug and an attractive alternative, you can shift the drug-taking behaviors if the alternative is attractive enough. People will choose the alternative reward instead of the drug. This has been shown in lab animals, in work we've done with crack cocaine users and work that we've done with methamphetamine users.

It's one of the most effective treatments we have, but it gets no or limited attention, in part because it's not sexy. You don't have a brain-imaging picture to show people, and so people are not interested. And to me, that's a shame. It's probably one of the most powerful technologies we have, and people are ignoring it.

We did a Monitor article on a program like that at Johns Hopkins a few years ago. The researchers give people jobs, where the price of admission is a clean drug test.

That's right. You're giving them job training skills, you're teaching them how to perform and behave in the workplace. These folks hadn't had this sort of level of education previously. It's so innovative — I just have a great deal of respect for the work people like Steve Higgins at the University of Vermont and Ken Silverman at Johns Hopkins are doing. Those people are taking this work out to the clinic, and they are using these procedures to help people deal with their drug addiction. So at some level I feel almost guilty talking about my lab, when these guys have been doing this work for years. They are partly the reason that I am so vociferous about this.

Recently, you've begun advocating the decriminalization of all drugs. Can you talk about how your research led you to decide that was the right drug policy?

It took me a long time to come to this position, but I've come to it based on the fact that I now know that our drug policies are based on false assumptions. The vast majority of people who use drugs don't get in trouble with drugs. The data we've collected for years show this.

For example, the drugs that we are really concerned with, in terms of overdose [deaths], are heroin and opioids. When you look at the data, you see the overwhelming majority of these people died not from the drug but from ignorance, because they combined them with alcohol or with another sedative. That's what kills them.

When we start to see that sort of stuff, that our drug policies are based on misapprehensions and inappropriate assumptions, and couple this with the fact that we arrest 1.5 million people every year for drugs — 80 percent of those for simple possession — something is very wrong. Then when you start to look at the fact that if you have a drug-related violation, it decreases the likelihood of your getting a job, it decreases the likelihood of your making a contribution to society. And the racial disparities in our enforcement of the drug laws, that just sickens me.

Decriminalization is not legalization. People still can get fined or receive some administrative sanction for drug possession, like a traffic violation. We can still send a message that we disapprove of this. But the disapproval should not ruin people's lives like it has been doing.

You've said that the goal of a drug-free society is not realistic. So what drug policy is achievable?

Well, you think about it in the same way you think about tobacco and alcohol. What is our goal with those drugs? We know people use those drugs to alter their consciousness, so we have to teach people to live with these drugs as safely as possible. The same is true with these other drugs. You just teach people how to live with these drugs, to enhance safety.

Have you seen the commercials that say, "Don't text and drive"? It's as simple as that. If you use heroin, don't combine it with alcohol because you increase the likelihood of overdose. It's simple, that's it.

As scientists, we're all concerned about education. Not to give people the proper amount and kind of education seems woefully irresponsible.

What about for the small percentage of people who do become addicted because of their own brain chemistry or outside forces? What does the research say we should be doing for them?

You treat the problem in the same way that you treat any other medical problem. You follow the best advice of experts. Our work shows that attractive alternative reinforcers can help some people with addiction. Other work shows the importance of making sure that you have treated the co-occurring psychiatric disorder that may be driving it.

People are addicted for a variety of reasons. Experts need to figure out what those reasons are, and then have the appropriate treatment that's recommended.

Think about driving an automobile. There are people who get in trouble with driving an automobile because they drink and drive, text and drive, drive too fast — whatever they do. We have interventions to help those people, to make our society safer. But we don't ban driving for the rest of us, yet that's what we do with drugs.

So I'm only saying, let's be rational. Let's get people the help they need, but do that in a smart, scientific way.

What's next for your own research?

I'm interested in drug combinations right now. Often times in my field, my area, we look at one drug at a time. I'm now trying to figure out what happens when people take multiple drugs, like they do in the natural ecology.

One last question: A lot of what makes your book so compelling is your personal story about your difficult childhood and adolescence. Why did you decide to write about that, and why now?

I know how important narratives are for people to be engaged. I have read enough boring science books in my life to know that you're not going to keep people's attention too long. That was one reason.

Another reason — and this caused me a great deal of anxiety — was that I wanted people to understand that I was not perfect, I made a lot of mistakes, and continue to, by the way. But there is this American mythology that if you are successful, you are perfect, and somehow don't have these warts. We do our young people such a disservice with that kind of thing. I wanted them to see that you can make mistakes and still be successful.