Wired for Addiction — Adolescents, Alcohol, and Drugs
By Kate Jackson
Social Work Today
Vol. 5 No. 4 P. 18

Adolescent neurocircuitry puts teens at greater risk for addictions—why “Just Say No” doesn’t work.

When people in his Kentucky hometown learned that he’d gained media attention for a study revealing that adolescents tend to be risk takers and are prone to addiction, says R. Andrew Chambers, MD, assistant professor of psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, they were ... well ... underwhelmed. Imagine them shaking their heads in disbelief. “Everyone knows that,” they might have said.

Well, yes, it may be stating the obvious, he laughs, but his research did more than conclude that adolescents stand on a dangerous precipice with respect to alcohol and drug addiction. In a study in the American Journal of Psychiatry, “Developmental Neurocircuitry of Motivation in Adolescence: A Critical Period of Addiction Vulnerability,” Chambers and coauthors reviewed the literature revealing that adolescent neurodevelopment occurs in the regions of the brain linked to impulsivity, motivation, and addiction and investigates the ways knowledge may be used to understand, treat, and prevent addiction in adolescents.

Chambers, who is also the director of the Laboratory for Translational Neuroscience of Dual Diagnosis Disorders at the Institute of Psychiatric Research, describes the study as an interpretation of animal research, human research, and different methodologies within those domains that tries to put together a big-picture overview of what may be happening in adolescents’ brains in terms of addiction and vulnerability. Based on an investigation of all those diverse lines of evidence, he says, the paper reveals that the ability of a drug to generate an addiction is more powerful when a person experiments with it during adolescence than when they use it in adulthood. There’s a great deal of clinical epidemiological evidence about the workings of the adolescent brain, he says, particularly in circuits known to be involved in the genesis of addiction.

Retooling the Brain
The research indicates that there are profound brain changes in several areas involved in addiction. “That kind of developmental plasticity,” he says, “may be particularly susceptible to the plastic effects induced by addictive drugs.” The brain, he says, has billions of neurons that are interconnected in neural networks. All our mental faculties—emotions, behavior, cognitions, perceptions—are possible because information is transferred through these networks. Plasticity, he explains, is the ability of those networks to rewire, as occurs when we learn new information. Education, in fact, is possible because of this plasticity. Neural networks change their connectivity as they transfer and store information and learning takes place. When individuals learn to play a sport, there’s plasticity in the areas of the brain that help coordinate motor activity. “When you learn a special skill, such as driving a car, you’re sort of retooling some neural networks in your brain that give you skills that allow you to be a safe driver,” says Chambers.

Plasticity is relevant to these healthy activities but also to unhealthy things such as the acquisition of a drug addiction, observes Chambers. “As individuals continually experiments or uses an addictive drug, we think that their motivation to use that drug starts to increase, and eventually it increases to the point at which they use or pursue the drug at risk to themselves and may sacrifice other motivations and be diagnosed with a substance use disorder.” As those motivational changes continue and the person continues to use the drug, there’s a kind of self-reinforcing cycle of use and increasing motivation to use, then using more in an increasingly vicious cycle until eventually the person may be diagnosed with substance dependence. Just as learning a new skill retools the brain, experimenting with addictive drugs may induce a neuroplastic response in neural networks that controls an individual’s motivations. By way of evidence, he notes that studies have shown that addictive drugs change receptor distributions, protein quantities, and cell form and morphology, and over time actually changing the shape of neurons and the brain subcircuitry that mediates addiction and motivation.

Beyond Peer Pressure
Arguing for the conclusion that adolescents are more vulnerable to addiction are epidemiological studies of human beings showing that individuals tend to acquire substance use disorders—either abuse or dependence—between the ages of 16 to 25. Like schizophrenia, this propensity appears to be developmental, occurring around the perioadolescent period. While some suggest that the motivation to drink or experiment with drugs may be more a matter of peer pressure, Chambers argues that peer pressure to use drugs occurs at all ages. Adolescents, however, he explains, want to explore and are entranced by novelty—in a variety of domains, including social, sexual, fashion, and the arts. “They’re very motivated, whether it be in academics or sports. They’re all in that together, and it’s cool to be explorers of adult roles.”

Adults, on the other hand, he says, tend to mellow out over time and become less vibrant and exploratory—a tendency he suggests may be neurobiological. “There’s very good evidence from all kinds of different methodologies in animal and human studies using neuroimaging that the prefrontal cortex—the part of the brain that has to do with decision making—is not fully developed, even in late adolescence,” a result of which, Chambers says, is impulsivity. As a consequence of this underdevelopment, adolescents are considerably more exploratory and show cognitive styles characterized by an attraction to novelty, newness, and risk.

Chambers and other scientists believe that one key mechanism through which addictive drugs do their work is the dopamine system, which is particularly important in learning and responding to novel situations. “So we think that an adolescent, because of the functionality of [his or her] underdeveloped prefrontal cortex in combination with a dopamine system that might in some ways be functionally more robust, is sort of set up for being more susceptible to the addictive properties of different drugs,” explains Chambers. For the most part, he says, these traits are normal and desirable. “If adolescents didn’t have the desire to explore, to be motivated, to be turned on by novelty, they wouldn’t learn.”

The addictive process, he says, is sort of a natural accident. All addictive drugs are known to stimulate dopamine—a key transmitter thought to be involved in changing the brain circuits that orient motivation. “Adolescents will naturally have those systems turned on pretty high because they need to explore, learn, and develop their motivations.” If, he speculates, they begin to develop a motivational drive to use drugs, it’s more likely that it will have a permanent effect if that occurs during adolescence.

What Rats Tell Us About Adolescent Drinking
Chambers’ colleague, Zachary A. Rodd, PhD, assistant professor in the department of psychiatry at the Indiana University School of Medicine, has done research with adolescent rats that supports the notion that adolescents are wired for addiction. “Through selective breeding, we have developed a rat line that’s phenotypically very similar to human alcoholics. They behave similarly and willingly consume large quantities of alcohol.” Rodd’s team began looking at whether adolescent rats would similarly consume alcohol in large quantities. “We have a lot of data and evidence suggesting that as soon as these rats are weaned at day 22 of life, they’ll start consuming large quantities of alcohol.”

The indication of their studies is that if a rat is genetically predisposed to consuming alcohol, you can potentiate the predisposition to consume alcohol, find alcohol reinforcing, and seek and crave alcohol by consuming alcohol during adolescence. “One way to summarize our studies so far is this: strike one is to have a genetic family history positive for alcoholism, strike two is to consume alcohol during adolescence, and strike three is continuing to consume alcohol during adulthood,” Rodd says.

It’s clear, then, that children of adult alcoholics who are known to have a greater risk could benefit by social efforts toward preventing them from drinking during adolescence. Rodd is quick to observe that adolescents tend to drink two days out of the week—on the weekend—and their drinking behavior is characterized by binging, defined as having more than five drinks on an occasion. They drink to get the maximum intoxicating effect. He and his coinvestigators are studying adolescent rats to determine how drinking is altering their brains, not just immediately after consuming the alcohol, but how their brains differ in adulthood from rats that had not consumed alcohol in adolescence. They’re looking at genetic markers that indicate a predisposition in hopes that pharmacotherapies can be developed to prevent and treat addiction in adolescents targeted as being at increased risk.

Implications for Prevention and Treatment
Most clinical research on addictions explores the problem as an adult disorder for which treatment tends to be offered after the neuroplastic effects have already occurred and when they may be extremely difficult to reverse. This is especially the case with the available pharmaceutical tools that, says Chambers, tend to be blunt instruments that are not very specific.

Highlighting addiction as a neurodevelopment disorder, he continues, makes a compelling argument that more needs to be done in terms of prevention and early intervention. Putting every adolescent on a drug to prevent addiction sounds Draconian, but it may be possible to target specific adolescents who are more vulnerable than others to addiction for preventative medication treatment.

He suggests something more akin to mammography for breast cancer screening. “In the case of adolescents, they may have a certain set of factors—environmental, family, genetic—that may be assessed on cognitive testing that would fit a profile of high-risk addiction vulnerability. Those kids could be put on a medication before they’re teenagers or as they’re entering teenhood, that would prevent addiction.” If that still sounds too Draconian, he offers a reminder that addictions, collectively, and medical and psychiatric illnesses associated with addictive drug use, are the leading causes of all medical morbidity and mortality in the United States.

The better we understand the nature of addictions as medical and neurobiological illnesses, says Chambers, and the more we understand the neurocircuits in the brain and the molecular events, as well as the neuroplastic events, the better we’re going to be able to understand how to target those systems for treatment.

— Kate Jackson is a staff writer for Social Work Today.

In the Meantime
Although pharmacotherapy that may help prevent or treat addiction may be a distant reality, research into adolescent addiction suggests at least one line of defense social workers can help advance now.

If you work with adolescents at risk, the most important thing you can do, suggests Zachary A. Rodd, PhD, assistant professor in the department of psychiatry at the Indiana University School of Medicine, is try to talk kids out of binging. “There are tons of studies showing that the pattern of alcohol consumption really affects the brain,” he says.

Abstinence is an unrealistic goal, but preaching tolerance and moderation can be beneficial. Research has shown that binging produces far greater neuroadaptation and neural damage than does moderate drinking.

Instead of telling kids to just say no, Rodd advises social workers to focus on getting adolescents to stop binging—“to break the cycle of going out and becoming highly inebriated.”

— KJ