Current Findings About Marijuana Use

Marijuana is the most commonly used illicit substance in the United States (Clark et al. 2002; Substance Abuse and Mental Health Services Administration 2003). According to the 2003 National Survey on Drug Use and Health, 14.6 million people ages 12 and older had smoked marijuana in the preceding month (Substance Abuse and Mental Health Services Administration

2004). It is estimated that approximately 4.3 million people used marijuana at levels consistent with abuse or dependence in the past year. Given that it is an illicit substance, any use of marijuana carries with it some significant risks. However, this document focuses on people who use marijuana heavily or are dependent on it. This treatment manual is directed primarily at these persons but may be useful for other persons with substance abuse or substance use disorders.

Studies have demonstrated that tolerance and withdrawal develop with daily use of large doses of marijuana or THC (Haney et al. 1999a; Jones and Benowitz 1976; Kouri and Pope 2000). About 15 percent of people who acknowledge moderate-to-heavy use reported a withdrawal syndrome with symptoms of nervousness, sleep disturbance, and appetite change (Wiesbeck et al. 1996).

Many adults who are marijuana dependent report affective (i.e., mood) symptoms and craving during periods of abstinence when they present for treatment (Budney et al. 1999). The contribution of physical dependence to chronic marijuana use is not yet clear, but the existence of a dependence syndrome is fairly certain. An Epidemiological Catchment Area study conducted in Baltimore found that 6 percent of people who used marijuana met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) (American Psychiatric Association 1994), criteria for dependence and 7 percent met DSM-IV criteria for substance abuse (Rosenberg and Anthony 2001). Coffey and colleagues (2002) found that persons who use marijuana more than once a week are at significant risk for dependence. In the 1990s, the number of people who sought treatment for marijuana dependence more than doubled (Budney et al. 2001). Therefore, a large group of adults who smoke marijuana is dependent and may need and benefit from treatment.

Surveys of people using marijuana who are not in treatment consistently show that a majority report impairment of memory, concentration, motivation, self-esteem, interpersonal relationships, health, employment, or finances related to their heavy marijuana use (Haas and Hendin 1987; Rainone et al. 1987; Roffman and Barnhart 1987; Solowij 1998). Similar marijuana-related consequences are seen among those seeking treatment for their marijuana use (Budney et al. 1998; Stephens et al. 1994b, 2000). People using marijuana who participated in previous treatment studies averaged more than 10 years of near-daily use and more than six serious attempts to quit (Stephens et al. 1994b, 2000). These individuals had persisted in their use despite multiple forms of impairment (i.e., social, psychological, physical), and most perceived themselves as unable to stop.

During the past decade evidence has emerged that a variety of problems are associated with chronic marijuana use. Although the severity of these problems appears to be less than that of problems caused by other drugs and alcohol, the large number of people using who may have these problems raises the possibility of a significant public health problem. Like those who use other mood-altering substances, many individuals who use marijuana chronically perceive the problems to be severe enough to warrant treatment.

The results of earlier studies on treatments for marijuana problems indicated that some adults who used marijuana responded well to several types of interventions, such as cognitive behavioral, motivational enhancement, and voucher-based treatments (Budney et al. 2000; Stephens et al. 1994b, 2000). Relapse rates following treatment were similar to those for other drugs of abuse and, as found with other types of substance abuse treatment, improvements in drug use were accompanied by other positive gains, including improvements in dependence symptoms, problems related to marijuana use, and anxiety symptoms. However, the generalizability of the treatment findings appeared to be limited by the predominantly white, male, and socioeconomically stable (i.e., educated and employed) characteristics of the samples. Therefore, the results of these studies may be limited to this fairly homogeneous group of people who are marijuana users.