In general, drug abuse is defined by the level and pattern of drug consumption and the severity of resulting functional problems. People who are dependent on drugs often use multiple drugs and have substantial health and social problems, including mental health disorders. One of the many challenges to providing effective treatment for addiction is the complicated nature of the disorder. Unlike other chronic diseases, drug addiction extends beyond physiological influence to include significant behavioral and psychological aspects. For example, specific environmental cues that a drug abuser associates with drug use can trigger craving and precipitate relapse, even after long periods of abstinence. Therefore, drug abusers may enter treatment a number of times, often reducing drug use incrementally with each treatment episode. Despite the potential for relapse to drug use, not all drug users require treatment to discontinue use. For those who require treatment, services are provided in either outpatient or inpatient settings and via two major approaches—pharmacotherapy and behavioral therapy—with many programs combining elements of both. Although abstinence from illicit drug use is the central goal of all drug abuse treatment, researchers and program staff commonly accept reductions in drug use and criminal behavior as realistic, interim goals. these funds support services provided by state and local grantees, which are given broad discretion in how best to use them. In numerous large-scale studies examining the outcomes of drug abuse treatment provided in a variety of settings, researchers have concluded that treatment is beneficial. Clients receiving treatment report reductions in drug use and criminal activity as well as other positive outcomes. The studies have also demonstrated that better treatment outcomes are associated with longer treatment periods but have found that retaining clients in treatment programs is problematic. Comprehensive analyses of the effectiveness of drug abuse treatment have been conducted by several major, federally funded studies over a period of nearly 30 years: the Drug Abuse Treatment Outcome Study (DATOS), the National Treatment Improvement Evaluation Study (NTIES), the Treatment Outcome Prospective Study (TOPS), and the Drug Abuse Reporting Program (DARP). These large, multisite studies—conducted by research organizations independent of the groups operating the treatment programs being assessed—were designed to measure people’s involvement in illicit drug and criminal activity before, during, and after treatment. Although the studies report on reductions in drug use from the year prior to treatment to the year after, most also track a subset of treatment clients for followup interviews over longer time periods. For example, DARP followed clients for as long as 12 years, TOPS for 3 to 5 years following treatment, and DATOS researchers are planning additional followup to determine long-term outcomes. These studies are generally considered by the research community to be the major evaluations of drug abuse treatment effectiveness, and much of what is known about “typical” drug abuse treatment outcomes comes from these studies. or outpatient methadone maintenance—regardless of the drug and client type. DATOS found that, of the individuals in long-term residential treatment, 66 percent reported weekly or more frequent cocaine use in the year prior to treatment, while 22 percent reported regular cocaine use in the year following treatment. Also, 41 percent of this same group reported engaging in predatory illegal activity in the year prior to treatment, while 16 percent reported such activity in the year after treatment. Previous studies found similar reductions in drug use and criminal activity. For example, researchers from the 1980s TOPS study found that across all types of drug abuse treatment, 40 to 50 percent of regular heroin and cocaine users who spent at least 3 months in treatment reported near abstinence during the year after treatment, and an additional 30 percent reported reducing their use. Only 17 percent of NTIES clients reported arrests in the year following treatment—down from 48 percent during the year before treatment. Another finding across these studies is that clients who stay in treatment longer report better outcomes. For the DATOS clients that reported drug use when entering treatment, fewer of those in treatment for more than 3 months reported continuing drug use than those in treatment for less than 3 months. DATOS researchers also found that the most positive outcomes for clients in methadone maintenance were for those who remained in treatment for at least 12 months. Earlier studies reported similar results. Both DARP and TOPS found that reports of drug use were reduced most for clients who stayed in treatment at least 3 months, regardless of the treatment setting. recommended at least 6 months in treatment; for both program types, the median treatment episode was 3 months. Because all of the effectiveness studies relied on information reported by the clients, the level of treatment benefit reported may be overstated. Typically, drug abusers were interviewed before they entered treatment and again following treatment and asked about their use of illicit drugs, their involvement in criminal activity, and other drug-related behaviors.Although this data collection method is commonly used in national surveys and drug abuse treatment evaluations, recent questions about the validity of self-reported drug use raise concerns about this approach. In general, self-reporting is least valid for (1) the more stigmatized drugs, such as cocaine; (2) recent use; and (3) those involved with the criminal justice system. A recent National Institute on Drug Abuse (NIDA) review of current research on the validity of self-reported drug use highlights the limitations of data collected in this manner. According to this review, recent studies conducted with criminal justice clients (such as people on parole, on probation, or awaiting trail) and former treatment clients suggest that 50 percent or fewer current users accurately report their drug use in confidential interviews. As questions have developed about the accuracy of self-reported data,researchers have begun using more objective means, such as urinalysis, to validate such data. For example, NTIES researchers found that 20 percent of those in a validation group acknowledged cocaine use within the past 30 days, but urinalysis revealed recent cocaine use by 29 percent. TOPS researchers reported that only 40 percent of the individuals testing positive for cocaine 24 months after treatment had reported using the drug in the previous 3 days. Because results from the major studies of treatment effectiveness were not adjusted for the likelihood of underreported drug use, reductions in drug use found may be overstated. However, researchers emphasize that client reporting on use of illicit drugs during the previous year (the outcome measure used in most effectiveness evaluations) has been shown to be more accurate than client reporting on current drug use (the measure used to assess the validity of self-reported data). Therefore, they believe that the overall findings of treatment benefits are still valid. Although supplementary data collection, such as hair analysis or urinalysis, can help validate the accuracy of self-reported data, these tools also have limitations. Urine tests can accurately detect illicit drugs for about 48 hours following drug use but do not provide any information about drug use during the previous year. In addition, individual differences in metabolism rates can affect the outcomes of urinalysis tests. Hair analysis has received attention because it can detect drug use over a longer time—up to several months. However, unresolved issues in hair testing include variability across drugs in the accuracy of detection, the potential for passive contamination, and the relative effect of different hair color or type on cocaine accumulation in the hair. We have reported on the limitations of using self-reported data in estimating the prevalence of drug use and concluded that hair testing merited further evaluation as a means of confirming self-reported drug use. Using federal treatment dollars most effectively requires an understanding of which approaches work best for different groups of drug abusers, but on this subject, research findings are less definitive. Although strong evidence supports methadone maintenance as the most effective treatment for heroin addiction, less is known about the best ways to provide treatment services to cocaine users or adolescents. treatment or psychiatric status, can significantly affect the patient’s performance in treatment. Current research generally does not account for these factors in evaluating the effectiveness of alternative approaches for specific groups of drug abusers. Methadone maintenance is the most commonly used treatment for heroin addiction, and numerous studies have shown that those receiving methadone maintenance treatment have better outcomes than those who go untreated or use other treatment approaches. Methadone maintenance reduces heroin use and criminal activity and improves social functioning. HIV risk is also minimized, since needle usage is reduced. As we have previously reported, outcomes among methadone programs have varied greatly, in part because of the substantial differences in treatment practices across the nation. For example, in 1990, we found that many methadone clinics routinely provided clients dosage levels that were lower than optimum—or even subthreshold—and discontinued treatment too soon. In late 1997, a National Institutes of Health consensus panel concluded that people who are addicted to heroin or other opiates should have broader access to methadone maintenance treatment programs and recommended that federal regulations allow additional physicians and pharmacies to prescribe and dispense methadone. Similarly, several studies conducted over the past decade show that when counseling, psychotherapy, health care, and social services are provided along with methadone maintenance, treatment outcomes improve significantly. However, the recent findings from DATOS suggest that the provision of these ancillary services—both the number and variety—has eroded considerably during the past 2 decades across all treatment settings. DATOS researchers also noted that the percentage of clients reporting unmet needs was higher than the percentage in previous studies. researchers have relied on cognitive-behavioral therapies to treat cocaine addiction. Studies have shown that clients receiving cognitive-behavioral therapy have achieved long periods of abstinence and have been successful at staying in treatment. The cognitive-behavioral therapies are based largely on counseling and education. One approach, relapse prevention, focuses on teaching clients how to identify and manage high-risk, or “trigger,” situations that contribute to drug relapse. A study of this approach showed cocaine-dependent clients were able to remain abstinent at least 70 percent of the time while in treatment. Another technique, community reinforcement/contingency management, establishes a link between behavior and consequence by rewarding abstinence and reprimanding drug use.