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Hooked: the complex roots of addiction

April 29, 2013

By the time Rebecca Morgan was 13, she had started down the tumultuous path of drug addiction. First, she tried marijuana, followed by cocaine, then methamphetamines. She would sometimes quit for months at a time, but it never lasted.

“Something would always draw me back,” Morgan says. “I would think, ‘I can just do it once and it will be fine.’ Then it would escalate from there.”

Most people can probably relate to this feeling to some degree. Whether it’s breaking a diet or having “just one” cigarette after resolving to quit, giving up our vices is incredibly difficult. In fact, almost 40 million Americans over the age of 12 suffer from addictions involving nicotine, alcohol or other drugs. Addiction is one of the largest and most economically draining public health problems facing the nation today. It’s more prevalent than diabetes, cancer or heart disease.

And addiction is a particularly tough disease to cure. For people with drug or alcohol dependencies, cravings can persist months or even years after they stop using the substance.

“People who become addicted remain vulnerable to relapse possibly indefinitely,” says Janet Neisewander, a professor and neuroscientist in ASU’s School of Life Sciences. Neisewander studies the short-term and long-term effects that certain drugs have on the brain.

Morgan knows firsthand how difficult it is to avoid relapse. At one point, she went more than seven months without using, but started again after getting into a relationship with a man who turned out to be an addict.

“You would think if I had a brain in my head I would have stayed clean,” Morgan says. Ironically, the brains in our heads are precisely why addiction is so difficult to overcome.

Why do smokers keep lighting up despite the known health risks? Why can’t some people stop eating junk food even though they know it’s making them obese? These questions are complicated to answer, but they start with the understanding that addiction is a disease of the brain.

Your brain on drugs

Neisewander studies several important mechanisms that occur in the brain with substance abuse. She is especially interested in the effects of psychomotor stimulants, such as cocaine.

“Our brains are like thermostats,” she says, explaining that the brain works constantly to maintain a stable internal environment, known as homeostasis. “When you deviate from that, the brain kicks in compensatory actions to try to restore that homeostasis.”

Cocaine disturbs homeostasis by interfering with the transfer of monoamine neurotransmitters in the brain. These neurotransmitters – dopamine, serotonin and norepinephrine – control mood, appetite, sleep, alertness, focus and motivation.

If you imagine your brain as a prison, monoamine neurotransmitters are like inmates that get released into a holding cell called the synapse. Normally, the neurotransmitter only remains in the synapse until a transporter protein – like a prison guard – brings it back into the neuron from which it was released. However, cocaine molecules will bind to that transporter protein and prevent it from doing its job. Jailbreak! The synapse becomes flooded with an excess of dopamine, serotonin and norepinephrine. An excess of these chemicals produces the feeling of a cocaine high.

Over time, this disruption in homeostasis causes changes in the brain as it attempts to compensate. If the user stops taking the drug, homeostasis will be disturbed again, creating a vicious cycle. Neisewander studies those changes. Her research aims to determine how they might affect the motivation for taking a drug and make users more susceptible to addiction.

“When people first start using drugs, reward pathways are activated that mediate the rewarding effects of the drug. But as they continue to take the drug, brain activity shifts to pathways involved in habit. Reward mechanisms become less influential over the behavior and it’s more the habit systems that are engaged,” Neisewander says.

Our ability to form habits can be incredibly useful. It allows us to do mundane tasks – like taking a shower or backing out of the driveway – without using a lot of mental energy. We also grow to crave the reward that certain habits give us. Imagine trying not to brush your teeth at the usual time.

Certain cues can lead us to engage in habits without even realizing what’s happening. That explains why simply being in a place associated with a drug experience can trigger craving and relapse. At this point, the user has less conscious control over what they are doing, which is a characteristic of addiction.

Of course, not everyone who tries cocaine will become an addict. One factor that affects vulnerability is the route of administration, or the way in which the drug is taken. For example, when cocaine is snorted, it takes a while for the drug to travel from blood vessels in the nose up to the brain. Some of the drug may not reach the brain at all. However, smoking or “freebasing” cocaine is an entirely different story. The drug’s chemical composition is altered, causing it to be absorbed into the bloodstream much faster and travel from the lungs to the heart up to the brain almost immediately. That immediate effect also occurs when the drug is shot directly into a vein.

“With the intravenous and the inhalation routes of administration, humans will report having a much more intense rush from the drug. A lot of times it’s described as being similar to a sexual orgasm, where the drug produces this intense euphoric effect that comes on very rapidly. That is one of the dangers of those routes of administration, compared to intranasal use,” Neisewander says.

Morgan experienced this difference herself, first with cocaine at an early age, and then with methamphetamines in her 20s.

“I was freebasing cocaine by 15. That was actually the first way that I ever tried cocaine, so it was very addictive and I was very quickly pulled into that scene,” she says.

She then made the transition from cocaine to methamphetamines. At first she preferred snorting meth and did so for years without ever feeling as though it was taking over her life. However, when her circle of friends began taking the drug intravenously, she did so as well.

“When I started shooting up, it was all over at that point,” Morgan says.

The social side of substance abuse

Morgan’s addiction was influenced by another key factor as well – the company she kept. In fact, Neisewander says, the social context in which a person takes a drug may actually change how rewarding that drug is on a biological level.

In social situations, your body releases the hormone oxytocin, which represses the stress response. Researchers believe that oxytocin helps reduce the stressful effects of cocaine on the brain, making the drug more rewarding when taken with other people. Animal models suggest this hypothesis is correct.

“Even rats, just like people, appear to find their drug more rewarding when they share the experience with another rat,” Neisewander says.

William Corbin, an ASU psychology professor, studies how peer influences affect the drinking behavior of late adolescent and college-age individuals. His research shows that perceptions of peer drinking habits can be powerful indicators of risk for developing alcohol-related problems.

“If you perceive that all of your peers are drinking heavily, you’re more likely to drink heavily yourself, which is going to increase your risk,” Corbin says.

Having preconceived beliefs about alcohol also makes a difference. For example, children and teenagers might think alcohol will make them funnier or more relaxed based on what they’ve seen on television and in movies. Corbin’s research shows that these expectations are predictive of how much minors will drink and how early they start drinking, which could have developmental consequences.

“We know the brain continues to develop into the early to mid 20s. Unfortunately, that’s when heavy drinking is often at its peak, so it may be especially problematic for brain development,” Corbin says.

However, dangerous drinking behavior doesn’t necessarily lead to addiction. A transition from social drinking to alcohol dependence tends to occur when people begin drinking in order to cope with negative emotions, rather than to enjoy the positive effects they get from alcohol. Another risk factor for addiction is solitary drinking.

“People who report drinking alone, that is associated more with drinking to cope or self-medication, which is predictive of more problems,” Corbin says.

And for those who boast about being able to hold their liquor – beware! Corbin’s research has shown that people who feel less of the impairing effects of alcohol actually have the greatest risk for developing dependence later on.

Alcohol addiction comes with severe long-term health risks. These include neurological problems, such as dementia and nerve damage, as well as liver diseases such as cirrhosis, a leading cause of death in the United States. But there are treatment options for alcoholics. Cognitive behavioral therapy, motivational interviewing and 12-step programs like Alcoholics Anonymous have all been shown to be relatively effective. The key, Corbin says, is to match individual patients with intervention strategies that will be likely to work for them.

Another option is a medication called Naltrexone, which blocks receptors in the brain related to pleasure and reward. Corbin was involved in a recent Yale University study looking at the efficacy of the drug combined with motivational therapy in heavy-drinking young adults. The participants involved weren’t actively seeking treatment, but agreed to see how the medication would work for them. Corbin says the study results were promising, despite the subjects’ low motivation to change their behavior.

Unfortunately, there is no equivalent prescription drug for people addicted to psychomotor stimulants like cocaine and methamphetamines. Neisewander is interested in developing such medications, and has a project under way that may lead to an effective treatment.

Help for getting help

Even if a medication does become available, many people will never be diagnosed for their addictions.

“An insufficient amount of financial resources are allocated to addiction,” says Myles Lynk, a professor and faculty fellow of the er for Science, Technology and Innovation at ASU’s Sandra Day O’Connor College of Law. Lynk served as a member of the Center for Addiction and Substance Abuse at Columbia University’s National Advisory Commission on Addiction Treatment.

In 2012, the commission presented a five-year study showing that addiction is a seriously underfunded and poorly understood area of public health. It also found that 90 percent of addicts never receive any form of treatment.

Lynk notes that most addiction treatment providers do not have medical training or advanced education in addiction science. In fact, medical professionals and doctors actually make up the smallest share of providers of addiction treatment services. He argues that treatment needs to be better informed by the neuroscience of addiction.

“We need treatment modalities that address this core problem of addiction, not just the manifestations of the problem in what substance you abuse,” he says.

Until this happens, addicts will continue to go without the treatment they need. Many will end up in prison. That’s where, at age 27, Rebecca Morgan was finally able to get clean. For her, prison was a blessing in disguise – it saved her from potentially overdosing and gave her the opportunity to start over.

“I couldn’t remember ever feeling so good and so healthy. And I started learning. I started going to college when I was in prison, and I learned that there are other ways to gain that feeling,” Morgan says. “I started achieving things and it made me feel good. Now it’s almost like achievement is my addiction.”

Morgan’s story has a happy ending. She is now a mom with a successful career as a human resources specialist. She owns her own home and will complete a bachelor’s degree in human resource management in August. She was able to conquer her addiction, but there are many others that cannot. Addiction as a disease is not well understood, and as a result, takes an enormous toll on society. Prison may have helped Morgan, but at what cost?

“We have literally millions of people who are either addicted to a substance or are chronic users of a substance,” says Lynk. “We’ve devoted a huge amount of law enforcement resources, judicial resources and incarceration resources to dealing with this problem. Are there better solutions? If we had more effective and more available treatment options, would we be able to reduce the amount of law enforcement-related resources we have devoted to this problem?”