Marijuana as a Gateway Drug
Marijuana is commonly referred to as a gateway drug. Some research has been used to support marijuana as a type of stepping stone to more dangerous drug choices (Morral, McCaffrey & Paddock, 2002). This information supports the “gateway hypothesis,” which argues that substance abuse is triggered by a progression of events that begins with use of an illegal substance such as alcohol or tobacco and then moves on to marijuana and then cocaine or another illicit drug.
Other research has supported the idea that there is actually at times a reverse gateway effect, in which social or individual circumstances are the factors responsible for initiating illicit drug use (Lessem et al., 2006).
A study by Tarter, Vanyukov, Kirisci, Reynolds and Clark published in 2006 reviewed the gateway hypothesis and studied whether it exposed a pattern for the transition from licit to illicit drugs.
The study used 224 male participants aged between 10 and 12 years of age, and assessed them at the ages of 12 to 14, 16, 19 and at age 22. Each participant was the son of men who were participating in another study, which included subjects who had a history of illicit drug use.
During each administration of the questioning, researchers used the Structural Clinical Interview for DSM-III-R to assess whether the participants met criteria for substance abuse disorders. The participants also self-administered the Drug Use Screening Inventory and took drug tests (both urine tests and alcohol breath tests) to obtain evidence of recent activity. In addition to these drug-use related screenings, the researchers also questioned the participants about social, family, psychological and educational characteristics and measured them using 35 variables.
The participants were grouped according to three different sequences of drug and alcohol use. The first group was comprised of participants who used alcohol and/or tobacco at the baseline, but had not moved on to using marijuana by age 22. The second group used alcohol and/or tobacco and then used marijuana by the age of 22. The third group used marijuana and then later used alcohol and/or tobacco by the age of 22.
The researchers found that the participants did not necessarily follow the pattern proposed by the gateway hypothesis. Participants whose behavior supported the gateway hypothesis were also associated with other social and family circumstances such as deviant behavior, a deviant social network, were less involved at school, and more likely to discontinue substance abuse than their counterparts who used only licit drugs up to age 22.
The study has limitations, including that much of the information was obtained using self-report, which is subject to bias. Some participants may exaggerate use to dramatize their situation and others will under-report use because of fear of legal sanctions.
The study is helpful, however, in looking at the gateway hypothesis more clearly. The gateway hypothesis is not applicable in all circumstances, nor are drug behaviors consistent across users of a specific drug. This study suggests that instead the patterns of drug use are influenced by a group of general social risk factors, such as parental influence and involvement in school.
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