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The effects of addiction on brain function…and of brain function on addiction

The hallmarks of addiction and its influence on the brain are threefold: craving for the object of addiction, loss of control over the use of that object, and continuing use despite negative consequences.

The term “addiction” was for a long time applied only to substances, such as alcohol and addictive drugs, but more recent research has shown that the term “addiction” is legitimately applicable, and not just in a loose, slangy way, to such pleasurable activities as gambling, shopping, and sex.

Nearly 23 million Americans are addicted to some substance. That’s nearly one in 10 individuals. Of these, over two-thirds abuse alcohol, whether or not they also abuse drugs.

Nearly a century ago, people with substance abuse issues—a term that did not yet exist at that time—were considered either weak-willed or morally deficient. Now we consider substance abuse issues to be a function of the brain, in a vicious cycle wherein the brain causes the individual to crave the substance, and overindulging in the substance causes further damage to the brain.

Where, in the 1930s and earlier, substance abusers were treated with punishments or urged to have stronger will power, now we recognize substance abuse as a disease and treat it accordingly.

The brain understands the principle of “pleasure,” regardless of the source, which may be alcohol, a psychoactive drug, sex, a delicious and filling dinner, a financial windfall, a relaxing massage, or any other strong enjoyment. When the individual experiences pleasure, the brain releases the neurotransmitter dopamine in a cluster of nerve cells called the nucleus accumbens. All drugs of pleasure—including nicotine—cause a particularly powerful surge of dopamine.

Will the use of a drug, or the participation in gambling, sex, or another pleasurable activity, lead to addiction? This depends largely on the speed with which the activity promotes dopamine release, the intensity of the release, and the reliability of the release. As far as drugs are concerned, the method of administration bears on how likely the use of the drug is to lead to addition. Smoking or IV injection will produce a faster, stronger dopamine signal than will swallowing the drug, and is more likely to lead to abuse.

According to Richard Ridderinkhof, professor of neurocognitive development and aging at the University of Amsterdam, “Evidence shows that heavy alcohol use modifies the structure and physiology of the brain… Recent neuroimaging studies have revealed that chronic alcoholism can damage the cerebellum, which plays an important role in regulating motor control, attention, and language. It can also cause the prefrontal cortex to shrink and degrade, potentially impairing decision-making skills and social behavior. Studies have also found damage in the white matter of the brain, which connects these regions…. Researchers have studied the effects of abstinence on the brains of alcohol-dependent individuals by comparing subjects recovering from years of alcohol abuse with those who do not drink or drink minimally. Scientists have also investigated changes in brain volume in initial versus sustained abstinence in one set of subjects. Several of these studies have shown that years of abstaining from booze can allow brain regions to return to their original volume and can repair neural connections across different regions. Much of this restoration occurs in the system most adversely affected by chronic alcoholism—the frontocerebellar circuitry, which regulates decision making, reasoning and problem solving.”

So there is hope for a total or near-total recovery from the effects of alcohol addiction—and perhaps other addictions as well, although Professor Ridderinkhof did not address those—if steps are taken to help the addicted individual master his or her addiction.

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