Addiction and the Brain's Pleasure Pathway: Beyond Willpower
- Addiction can develop despite a person's best intentions and in spite of their strength of character.
- Repeated drug use disrupts complex but well balanced systems in the human brain.
- Many people are addicted to more than one substance, complicating their efforts to recover.
The human brain is an extraordinarily complex and fine-tuned communications network containing billions of specialized cells (neurons) that give origin to our thoughts, emotions, perceptions and drives. Often, a drug is taken the first time by choice to feel pleasure or to relieve depression or stress. But this notion of choice is short-lived. Why? Because repeated drug use disrupts well-balanced systems in the human brain in ways that persist, eventually replacing a person's normal needs and desires with a one-track mission to seek and use drugs. At this point, normal desires and motives will have a hard time competing with the desire to take a drug.
How Does the Brain Become Addicted?
Typically it happens like this:
- A person takes a drug of abuse, be it marijuana or cocaine or even alcohol, activating the same brain circuits as do behaviors linked to survival, such as eating, bonding and sex. The drug causes a surge in levels of a brain chemical called dopamine, which results in feelings of pleasure. The brain remembers this pleasure and wants it repeated.
- Just as food is linked to survival in day-to-day living, drugs begin to take on the same significance for the addict. The need to obtain and take drugs becomes more important than any other need, including truly vital behaviors like eating. The addict no longer seeks the drug for pleasure, but for relieving distress.
- Eventually, the drive to seek and use the drug is all that matters, despite devastating consequences.
- Finally, control and choice and everything that once held value in a person's life, such as family, job and community, are lost to the disease of addiction.
What brain changes are responsible for such a dramatic shift?
Research on addiction is helping us find out just how drugs change the way the brain works. These changes include the following:
- Reduced dopamine activity. We depend on our brain's ability to release dopamine in order to experience pleasure and to motivate our responses to the natural rewards of everyday life, such as the sight or smell of food. Drugs produce very large and rapid dopamine surges and the brain responds by reducing normal dopamine activity. Eventually, the disrupted dopamine system renders the addict incapable of feeling any pleasure even from the drugs they seek to feed their addiction.
- Altered brain regions that control decisionmaking and judgment. Drugs of abuse affect the regions of the brain that help us control our desires and emotions. The resulting lack of control leads addicted people to compulsively pursue drugs, even when the drugs have lost their power to reward.
The disease of addiction can develop in people despite their best intentions or strength of character. Drug addiction is insidious because it affects the very brain areas that people need to "think straight," apply good judgment and make good decisions for their lives. No one wants to grow up to be a drug addict, after all.
Co-occurring Addictions: Compounding Complexities
It is not unusual for an addicted person to be addicted to alcohol, nicotine and illicit drugs at the same time. Addiction to multiple substances raises the level of individual suffering and magnifies the associated costs to society. No matter what the addictive substance, they all have at least one thing in common - they disrupt the brain's reward pathway, the route to pleasure.
What is the best way to treat people who are addicted to more than one drug?
- Medications. In some cases, medications developed for one addiction have proven useful for another. For example, naltrexone, which can help former heroin users remain abstinent by blocking the "high" associated with heroin, has been found to be effective in treating alcoholism.
- Behavioral therapy or other psychotherapy. Behavioral therapies do not need to be specific to one drug and can be adapted to address use of multiple or different drugs. It is the disease of addiction that the therapy addresses.
- Combined medications and behavioral therapy. Research shows that this combination, when available, works best.
- Multipronged approach. Treatment for multiple addictions should be delivered at the same time. This is especially true because there are always triggers, such as trauma, depression, or exposure to one drug or another, that can put the recovering addict at risk for relapse. In addition, treatment must consider all aspects of a person - their age, gender, life experiences - in order to best treat their drug addiction. Although the type of treatment may differ, it should always strive to address the entire person through a multipronged approach that tackles all co-occurring conditions at once.
Relapse: Part of Addiction as a Chronic Disease
Despite the availability of many forms of effective treatment for addiction, the problem of relapse remains the major challenge to achieving sustained recovery. People trying to recover from drug abuse and addiction are often doing so with altered brains, strong drug-related memories and diminished impulse control. Accompanied by intense drug cravings, these brain changes can leave people vulnerable to relapse even after years of being abstinent. Relapse happens at rates similar to the relapse rates for other well-known chronic medical illnesses like diabetes, hypertension and asthma.
How is relapse to drug abuse similar to what happens with other chronic diseases?
- Just as an asthma attack can be triggered by smoke, or a person with diabetes can have a reaction if they eat too much sugar, a drug addict can be triggered to return to drug abuse.
- With other chronic diseases, relapse serves as a signal for returning to treatment. The same response is just as necessary with drug addiction.
- As a chronic, recurring illness, addiction may require repeated treatments until abstinence is achieved. Like other diseases, drug addiction can be effectively treated and managed, leading to a healthy and productive life.
To achieve long-term recovery, treatment must address specific, individual patient needs and must take the whole person into account. For it is not enough simply to get a person off drugs; rather, the many changes that have occurred - physical, social, psychological - must also be addressed to help people stay off drugs, for good.
Repeated drug exposure changes brain function. Positron emission tomography (PET) images are illustrated showing similar brain changes in dopamine receptors resulting from addiction to different substances - cocaine, methamphetamine, alcohol, or heroin. The striatum (which contains the reward and motor circuitry) shows up as bright red and yellow in the controls (in the left column), indicating numerous dopamine D2 receptors. Conversely, the brains of addicted individuals (in the right column) show a less intense signal, indicating lower levels of dopamine D2 receptors.