Addiction researchers and treatment professionals have long known that drug addiction and alcoholism are strongly linked. In the last decade, research has broadened our understanding of many shared neurobiological and behavioral mechanisms that underpin the two disorders. Yet, while two in five substance abuse treatment patients abuse both drugs and alcohol, the treatment they are likely to receive will target only one disorder. A lack of science-based information on concurrent treatment of drug and alcohol abuse limits the ability of treatment professionals to provide the comprehensive treatment these patients need.

Recent research suggests that some medications developed to treat drug or alcohol abuse may be useful for treating both problems. This information, along with our increased understanding of the underlying factors that drive drug and alcohol abuse, provides a strong rationale for a coordinated research effort to meet the critical need for treatments for people suffering from both disorders. Toward that end, NIDA and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) have issued a joint program announcement (PAS-03-029) to spur both drug and alcohol abuse researchers to investigate all aspects of pharmacological treatment for dually addicted patients.

Recent research suggests that some medications developed to treat either drug or alcohol abuse may be useful in treating co-occurring substance abuse.

Coordinated research on dually addicted patients will address the needs of the overwhelming number of Americans who abuse both alcohol and illicit drugs. More than 2.4 million of the 5.6 million people who abused illicit drugs in 2001 also abused alcohol, according to the National Household Survey on Drug Abuse. In fact, the more heavily someone abused alcohol, the more likely he or she was to use illicit drugs, the survey found. In 2001, nearly two of every three American teenagers, ages 12 to 17, who engaged in frequent drinking binges also abused drugs. In comparison, only 1 in 20 young people who didn't drink at all used drugs.

The substantial portion of drug- and alcohol-abusing patients in community treatment programs provides additional evidence of the need for science-based information on treating dual addiction. Patients who abuse both drugs and alcohol accounted for more than 42 percent of admissions to substance abuse treatment facilities reported by State agencies in 2000, the last year for which these data are published. Alcohol abuse is even more likely among patients who abuse certain drugs, such as cocaine, methamphetamine, and marijuana. For example, more than half of cocaine-abusing patients who entered treatment in 2000 also abused alcohol.

We aim to generate a broad spectrum of useful clinical information about appropriate sequencing or combining of medications and behavioral therapies, possible drug interactions that could affect optimal dosages, and unique requirements of specific groups of dually addicted patients...

To develop effective treatments for patients who abuse both drugs and alcohol, we need to understand why so many people do so. Part of the answer probably has to do with genes--underlying genetic variations that may play a role in common brain mechanisms that fuel both disorders. NIDA-supported brain imaging studies conducted at Brookhaven National Laboratory in Upton, New York, have documented similarities in the structure and function of the brains of alcoholics and chronic cocaine abusers that appear to be implicated in the abuse of both substances. Individuals with either disorder have low levels of dopamine D₂ receptors in the brain's reward pathways that may impair their capacity to derive pleasure from normally rewarding activities. This deficit may make them more vulnerable to the rewarding effects of alcohol and cocaine.

Dually addicted individuals also may combine alcohol and illicit drugs because of interactions between abused substances in the body. Because both drugs and alcohol activate brain areas involved in reward, combining substances may increase these effects. Other alcohol-drug interactions may counter unpleasant effects that often accompany or follow substance abuse. Clinical reports suggest that cocaethylene, a combined cocaine-alcohol metabolite that is formed in the body following concurrent alcohol and cocaine use, appears to reduce the anxiety that can accompany cocaine use. Recent research in rats confirms that cocaethylene plasma levels remain high as cocaine levels fall, producing a delayed, relatively long-lasting rewarding effect that may counter the aversive effect induced when cocaine plasma levels recede.

While the perceived benefits of combining alcohol and drugs may play a big part in the high percentages of people who do so, the addictive effects and harmful consequences of both substances increase when they are used together. Dually addicted patients are more likely to drop out of treatment and have poorer results than patients who abuse only one substance. However, since most studies on treating drug and alcohol abuse have examined these disorders separately, drug and alcohol treatment counselors now have little science-based information on which to base their treatment of these patients.

The joint NIDA-NIAAA program announcement addresses the critical need for effective approaches to treating dually addicted patients.

The joint NIDA-NIAAA program announcement addresses this critical need for effective approaches to treating dually addicted patients. Our research partnership seeks studies that will evaluate the efficacy of established drug and alcohol treatment medications and novel pharmacological agents in patients with concurrent addictions. We aim to generate a broad spectrum of useful clinical information about appropriate sequencing or combining of medications and behavioral therapies in dually addicted patients, possible drug interactions that could affect optimal dosages, and unique requirements of specific groups of patients, such as minorities, the elderly, and adolescents.

Drug and alcohol abuse wreak incalculable damage on individuals, families, and communities. When they occur together, these disorders double the challenge to researchers and treatment providers. Now, NIDA and NIAAA have launched a concerted scientific response to address these challenges. Ultimately, this expanded research will fuel the development of new treatments that will enable substance abuse treatment programs to more effectively meet the needs of the many patients who abuse both alcohol and illicit drugs.

Volume 18, Number 1 (June 2003)