History of Cannabinoid Use
Cannabis is the most commonly used illicit drug in the United States. The 2011 United States National Survey on Drug Use and Health from the Substance Abuse and Mental Health Services Administration estimated that 107.8 million people aged 12 and older (42%) had ever engaged in marijuana use, and 29.7 million people aged 12 and older were last-year users of marijuana (11.5%). Notable statistics from this survey included the following. In 2011, of those people aged 12 or older who ever used in the last year, 4.2 million (13.9%) showed cannabis abuse or dependence (Substance Use Disorder based on the Diagnosticand Statistical Manual of Mental Disorders, 5th edition [DSM-5] criteria), and 2.6 million (8.8%) of those who ever used in the last year showed cannabis dependence (DSM-IV criteria).
The Gateway Hypothesis of the trajectory of the evolution of drug use, particularly in adolescents, was originally formulated as four stages in the sequence of involvement with drugs: beer or wine or both, cigarettes or hard liquor, cannabis, and other illicit drugs (for further reading, see Kandel, 1975). Relevant to the present section, the Gateway Hypothesis has been invoked most often in the link between the use of cannabis and the subsequent use of other illicit drugs, with much support generated for such a link but not necessarily causality. Some work now shows a significant association between the frequency of cannabis use and frequency of the use of other illicit drugs, even when genetic, environmental, and individual variables are controlled, leading some to argue for a causal link between the use of cannabis and the use of other illicit drugs (for further reading, see Fergusson et al., 2006).
Marijuana has long been argued to be a “Gateway Drug” (Box 8.2). In a report of adolescents referred for conduct and substance abuse problems, cannabis, tobacco, and alcohol had the highest overall prevalence, with a rapid progression from first use to regular use (Figure 8.3). Long-term trends have shown increases in marijuana use in the 1960s and 1970s, declines in the 1980s, and increases again in the 1990s. In the mid-1960s, only 5% of young adults aged 18–25 had ever used marijuana, but this increased to 54% in 1982 (Figure 8.4) and has remained relatively steady since then.