Marijuana: Smoking Style Tied to Addiction Risk


The word addiction means “enslaved by” or “bound to”, and anyone who has experienced an addiction themselves or has witnessed a loved one struggling with an addiction knows how very much the word lives up to its reputation. As with many other addictions, it seems that it is behavior, rather than the potency of marijuana itself, that determines the risk of addiction to the drug.  It also does not seem to matter, according to a cross-sectional study reported in Addiction, how much of the psychoactive chemical delta-9-tetracannabinol, more commonly referred to as THC, that the smoker consumes.  It comes down to behavior.

Researchers wanted to determine whether marijuana smokers who smoked higher potency joints were more or less likely to become dependent on the drug.  According to the National Longitudinal Study of Adolescent Health, youth 16 years of age and younger who reported using alcohol, marijuana or tobacco were more likely to be substance users when they reached adulthood.  Furthermore, users of all three of these chemicals at an early age were more than two times as likely to become addicted to marijuana.  For this particular study, lead author Peggy van der Pol of the Trimbos Institute of the Netherlands Institute of Mental Health and Addiction notes that many people do not fully appreciate that there is not a single drug without risk.

The report, Cross-sectional and Prospective Relation of Cannabis Potency, Dosing and Smoking Behaviour with Cannabis Dependence: an Ecological Study, was released in Addiction this month, and states that previously, many in the medical field believed that high THC doses in marijuana was what influenced pot smokers to become addicted.  Van der Pol notes that this is not so; there are other factors that influence addictive behaviors.

At the beginning of the study, 98 subjects were recruited from coffeehouses in the Netherlands where it was legal to smoke marijuana, and 33 percent of those involved were identified as meeting the criteria for being addicted to marijuana.  Three quarters of the participants were male and roughly 23 years of age.  Every 18 months, and then another 18 months after that, researchers would interview participants to determine what they could about the rates at which they smoked pot.  Users were instructed to bring their own cannabis into the room and roll their own joints, and these joints had varying concentrations of THC in them.

Researchers learned very quickly that smokers would automatically adjust the volume of smoke they took in based on the dose of the THC; the higher the dose, the lower the inhalation volume.  They also tended to smoke at a slower rate than their peers with lower doses of THC in their marijuana.  What this showed researchers was that it was smoking style or behavior and not the dose of THC in the marijuana that governed whether they became addicted.

Behavioral patterns such as how much of the joint they smoked or how frequently they puffed were the only consistent predictors of whether someone was addicted by the time the three-year study was over.  Their level of addiction to the drug prior to the study did not seem to be a factor in their level of addiction at the end of the three years, either.

One finding that remained consistent, however, was that those who smoked joints with higher doses of THC generally were exposed to greater amounts of the drug.  No matter how much smokers self-adjusted their marijuana intake either by adjusting their inhalation volume or how quickly they smoked, their smoking behaviors were the predictors of whether or not they were addicted at the end of the three-year study.  Regardless of the dosing, it is the behavior of the marijuana smokers that govern their addiction, not the dosing of the drug itself, which smokers can adjust for to a degree.  Van der Pol notes while the study sample size was small, the study revealed telling information about smoking behaviors.  She says while smoking behaviors may be largely unconscious in nature, users may also be unaware they try and adjust for the THC dose they take in when they smoke marijuana.

By Christina St-Jean




UT San Diego

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