What it is and why you’ve got it
By Robert Freed
The National Institute on Drug Abuse (NIDA), a unit of National Institutes of Health, could not be more categorically insistent on this point: “[Addiction] is considered a brain disease because drugs change the brain—they change its structure and how it works.”
Every human brain is different, but one psychological commonality is Freud’s pleasure principle. Freud skeptics may substitute philosopher and mythologist Joseph Campbell’s famous maxim, “Follow your bliss,” but the idea is similar: Given choices, people will opt for what feels good over what does not. “It’s a wonder that more of us aren’t addicted,” Baker says. “People are hardwired to seek out comfort.”
Part of the brain comprises something called the limbic system. It communicates with several parts of the nervous system to facilitate a variety of functions such as motor control, thoughts, emotional drives, feelings, perceptions, and, significantly vis-à-vis addiction, rewards. To perform the last task, the limbic system releases neurotransmitters including the well-known dopamine, which is really a messenger that conveys its pleasure impulses to nerve cells, or neurons. Drugs and alcohol are chemicals that, once introduced to the brain, meddle with its pleasure circuitry in different ways and with different effects.
In almost all cases, abusive substances hike up dopamine levels. According to Therissa Libby, a neurobiologist and an addiction science educator based in Annapolis, Maryland, some substances, such as cocaine and amphetamines, directly encourage the nervous system to produce abnormally high levels of natural neurotransmitters. “You get a rapid and powerful rush, an intense euphoria,” Libby says.
Cannabis (marijuana, hashish), opioids such as heroin, and often illicitly used pain relievers such as OxyContin have an indirect effect. They essentially impersonate neurotransmitters, latch onto neurons, and send warped messages to them. With continued drug use, the brain begins to taper down its natural production of dopamine.
Users then must outsource, so to speak, to keep up their sense of well-being. Natural dopamine levels diminish even more, and the drug dependence cycle has another victim in its grasp.
Alcohol, which Libby and other neurobiologists call a “dirty” drug for its opportunistic, multipronged attacks, stimulates dopamine like the others and gives even moderate drinkers the classic buzz. Yet alcohol hones in on other neurotransmitters, too, such as serotonin, glutamate, and GABA (gamma-aminobutyric acid).
In much the same way as other drugs inhibit dopamine production, alcohol diminishes the body’s natural production of serotonin, which is considered essential to emotional health. Glutamate plays a huge role in cognition, so if alcohol abuse suppresses its activity over the long haul, learning, memory, and other such skills may be permanently impaired.
GABA regulates inhibition, and when alcohol stimulates GABA, the result is sluggishness and weakened muscle tone. Over time, changes in GABA functions may encourage alcohol dependence and higher tolerance. Even worse, an irregular GABA system may play a role in establishing a predisposition toward alcoholism.
At the same time, NIDA points out that the human body possesses marvelous regenerative powers. MRI images of the brain’s dopamine transporter frequently show a remarkable (though partial) recovery after several months of abstinence, even with so destructive a drug as methamphetamine.
Yet this brief side trip through the brain begs two serious questions: Why do some people become alcoholics and chronic drug users while others do not? And at what point does a chronic abuser become an addict?
The Fine Line of Addiction
Even before addiction takes hold, a genetic predisposition toward dependent behavior often lurks in the chemical makeup of many individuals. Naturally, the odds go up tremendously when social, psychological, and co-existing medical condition — age, age of initiation, a multitude of stressors, mode of administration, gender, availability and exposure, socioeconomic status — negatively come into play. Although genetically based susceptibility accounts for 40% to 60% of the chance of addiction, most experts agree that the more risk factors an individual must contend with and the greater their severity, the higher the possibility of eventual dependence.
Nonetheless, over the past few years, research on the human genome has uncovered the actual difference between those who have developed the disease of full-blown addiction (and exhibited self-destructive behavior) and those who have not: The truth is that scientific research has its limits. Physicians can’t diagnose the condition by putting people behind fluoroscopes like something done in an old Daffy Duck cartoon.
Correspondingly, the American Psychiatric Association’s DSM-IV yardsticks to determine alcohol abuse, for example, are framed to keep the parameters wide. They include such criteria as absence and/or negligence at work, school or home; repeated incidents of drunk driving; and continued drinking despite “significant” emotional problems.
The same goes for the DSM-IV regarding fully developed alcohol dependence, with references to higher tolerance, withdrawal symptoms, “more and longer” drinking, and inability to quit.
“When you’re awake at dawn, it isn’t easy to determine when night stops and day begins,” Baker says. “It’s the same with abuse and addiction. Plus, we’re all wired differently.”
For these reasons, Richard Sandor, past president of the California Society of Addiction Medicine, and others in the treatment field rely on their patients’ testimony. “It is so important to listen carefully to the stories of alcoholics and addicts themselves — to hear what they say about what’s going on inside them,” he writes in a recent online article. “When we do that, we learn that they describe their experience as ‘powerlessness.’”
Crossing the Line
That feeling of powerlessness is a crucial distinction between addiction and nonaddiction. It, in turn, springs from automaticity, which is the nervous system’s supervision and performance of tasks with little to no need for “front burner” concentration. Breathing is an involuntary automaticity; riding a bicycle, to offer the always-cited illustration, is an automatism that we acquire as we get older. It’s a way to free us to engage simultaneously in more complicated activity, and once one is learned, it cannot be forgotten.
Addictions, Sandor believes, are complicated, higher-level automatisms. After people with vulnerability to addiction try the substances, these malefactors only become more ingrained as time passes and eventually come to dominate almost every corner of the think-feel-act psychological triad. “Something inside has acquired a life of its own,” Sandor explains. “When that something threatens the well-being of the whole (just like runaway blood pressure), then it is rightly considered a disease.”
More often than not, though, victims themselves are the last to know. People with other types of disease often attribute clear warning signs to signal a problem. But substance addicts do not benefit from such signals — the awareness of the loss of control seldom strikes like a thunderbolt in the early stages of addiction. Once again, the culprit for this self-delusion is the substance-affected brain. “The sense of powerlessness comes on gradually,” Baker says. “People rarely think to themselves, ‘Oh! I’m putting myself at risk, and I’d better back off.’ It just doesn’t work like that.”
Another way in which addiction differs markedly from most other medical conditions is the degree of resolve its sufferers must summon to keep it in check. Nowadays, some pharmacotherapeutics are available, such as buprenorphine, for people with non-entrenched opioid addiction, and naltrexone, a longer-acting medication for alcohol, heroin, and prescription painkiller dependence, but most treatment professionals still opt for abstinence. At-risk teens and young adults provide a less clear diagnostic path, but, offers Libby as an example, “A binge drinker may or may not be an alcoholic, so for a real life change, abstinence is the way to go.”
No one will ever say recovery is easy. In fact, as worthwhile as it is, recovery is probably the single most difficult challenge the majority of addicts will ever face, primarily because it never ends. Even though Baker says he has no cravings at all, he freely acknowledges, “This is something that we always have to manage.
Dopamine’s Reaction with Addictive Chemicals
To create that good feeling, the limbic system releases neurotransmitters including the well-known dopamine, which conveys pleasure impulses to nerve cells, or neurons. Drugs and alcohol are chemicals that, once introduced to the brain, meddle with its pleasure circuitry and impersonate neurotransmitters, latch onto neurons, and send warped messages to them.
With continued drug use, the brain begins to taper down its natural production of dopamine.
Users then must outsource, so to speak, to keep up their sense of well-being. Natural dopamine levels diminish even more, and the drug dependence cycle has another victim in its grasp.
Robert Freed is a writer and editor with more than 25 years of experience. As a former medical and dental editor, he has written numerous articles on health care.
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