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Harvard Commentaries
35320
Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School


Minding Your Mind Minding Your Mind
 

Time To Stop Just Saying No


November 14, 2013

By Michael Craig Miller M.D.

Harvard Medical School



Just say no? It turns out that such an approach to treating addictions never made much sense. What scientists have learned about the biology of addiction should help them persuade policy makers — if they're listening — to move resources off the borders, out of courts and prisons, and into the clinic.

Addiction is a chronic illness that is as expensive as it is tragic. It affects more than 20 million Americans and costs our nation almost $500 billion per year — more than diabetes and cancer combined.

The difficulty with addiction is not the product of bad character or weak moral fiber. Rather, it results from brain circuits being on the blink.

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Hijacking the Reward System

Addictive substances commandeer the brain's reward system and undermine people's determination to make wise choices, even when they know they are likely to suffer as a result.

Since faulty brain circuits don't return to normal right away, if ever, detoxification is rarely enough to keep someone sober. Long-term treatment is essential, and usually requires psychotherapy (to provide emotional support, enhance motivation and reduce stress) along with medication to counter the brain changes shaped by the addictive drug.

A feature common to all addictive drugs is that they stimulate the release of the chemical messenger dopamine into a cluster of nerve cells deep in the brain called the nucleus accumbens. This yields a sensation of pleasure that many people want to experience again and again. Cocaine and other stimulants cause this change directly, but other substances — alcohol, narcotics, nicotine and marijuana — all do so at least indirectly.

Could we ever find one treatment to cure every addiction? Probably not, because the cycle of addiction is too complicated — it upsets a dynamic balance between reward circuits and fear circuits. Addiction also stifles activity in the front part of the brain, where people decide what action is most important for survival. Multiple chemical messengers and their receptors are involved, not just dopamine.

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Medications to Cut Cravings

Scientists have used newer models of addiction to develop treatments that can make it a little easier to manage these disorders. The most conspicuous of these are the anti-craving medications.

The best known is naltrexone. Naltrexone, which blocks receptors for narcotics in the brain, has long been used to negate the effects of drugs like heroin. Now it also is being used to help alcoholics who want to stop drinking.

How could a medication that fights addiction to heroin, an opiate drug, also help an alcoholic? Alcohol boosts endorphins, the opioid chemicals that are produced by our brains. The endorphin boost is instrumental to how alcohol causes pleasurable sensations. By blocking opioid receptors, naltrexone makes drinking less rewarding, so there is less incentive to drink.

Another drug, acamprosate, interacts with receptors for another chemical messenger called glutamate. Because it has a different mechanism from naltrexone, patients can be given both drugs — a one-two punch against alcoholism.

There are several other drugs being investigated to cut down craving for alcohol, narcotics, stimulants like methamphetamine, and nicotine.

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Genes at the Root of the Problem

As with many medical problems, scientists are hunting for the genes that control the whole apparatus. About half of the vulnerability to addiction is attributed to heredity. Genes determine how sensitive you are to the drug's effects.

Let's use alcohol again to illustrate:

  • In people with a family history of alcoholism, the level of endorphins goes higher after a drink than it does in people without alcoholism in the family.
  • People with a gene variation labeled Asp40 get more benefit from naltrexone than those with a different variant of the gene.
  • Serotonin is a chemical that carries messages from nerve cell to nerve cell and is involved in regulating mood. There is a gene (5-HTTLPR) that influences serotonin concentrations by controlling how efficiently it is pumped back into nerve cells. Depending on which copies of that gene you get from your mother and father, you may be more or less likely to binge drink.

It's too early for these genetic differences to be useful to doctors. But markers like these, once better established, will help doctors choose the best treatment for individual patients.

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What's the Future?

For all addictions, we're still a long way from pills that will make treatment easy. The best treatment is still a combination of medication and psychotherapy over the long term.

Long experience of the difficulties of addiction may make us cautious, but the advances in science should leave us feeling optimistic nonetheless. As we get better educated about the science behind these illnesses, we will do a better job of just saying yes to people who need help with their addictions.

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Michael Craig Miller, M.D., is the editor in chief of the Harvard Mental Health Letter. He is also associate physician at Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School. He has been practicing psychiatry for over 25 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Harvard Longwood Psychiatry Residency Program.

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