Addiction and Impairment

Several people contacted me last week following my post about marijuana legalization and I want to add more specific information about some aspects of marijuana  that I think are somewhat misunderstood and not discussed in enough detail. The first is marijuana addiction. I have been telling people in the classes I teach that about 20 out of every 100 people who have been in my office for issues related to marijuana end up being addicted. This is consistent with statistics that I saw this week published by the National Institute of Drug Abuse ( that 9 percent of adults and 17 percent of teenagers become addicted. 

But marijuana addiction doesn’t look like addiction to cigarettes or heroin, which is why I think it isn’t always recognized as addiction. The best way to characterize marijuana addiction is that the most obvious symptom is a severe lack of motivation. Many people who talk to me about why they use marijuana tell me that they started smoking on the weekends as a way to relax. They have busy lives and are under a tremendous amount of pressure; this is particularly true of high-achieving high school students who are taking intense academic loads and participating in more extracurricular activities than they really have time to do. The effect of marijuana for these students is that it helps them relax and momentarily forget or just not care that they are under pressure.  In other words, they are enjoying that for some period of time they don’t need to be motivated. The problem is that for about 20% of them, this joy that they experience in not being motivated becomes an addiction to not being motivated. So, while many have no intention of smoking during the school week, the ones who are becoming addicted look for opportunities during the weekdays when they can take a quick break and get that same respite from the pressure they feel.  Weekends become weekends and Wednesdays and eventually the people who become addicts find themselves smoking every day.  

The more scientific perspective on this is that marijuana smokers who are addicted have a shift in their locus of control from being externally motivated to being internally motivated. Most people are externally motivated, in that, if they are threatened with some sort of consequence from the outside, they will respond and try to avoid consequences forced upon them from their families, schools, employers or the legal system.  A non-addicted teenager who is being told he will lose his car or other privileges if he doesn’t stop smoking will stop.  But someone who is truly addicted will not stop because what matters more than anything else is that internal feeling of relaxation they get from their high. A marijuana addict will give up most of the things they used to care about if those things interfere with their ability to smoke. The difficult position of being a parent or counselor who is trying to reason with an adolescent who is addicted to marijuana is that we are external motivators. As is true of most addictive drugs, it is only a forced inaccessibility to the drug that initiates the recovery from marijuana addiction. 

Another aspect of the effects of marijuana that I think is largely misunderstood is how to characterize impairment, particularly when it comes to driving. You can probably imagine that I have heard more than one person tell me they think they are a better driver high than not. This perspective comes because many people who smoke and drive are aware that they are impaired so they drive very slowly. And since they don’t have difficulty staying in their lane, which is what one typically imagines when they think of a driver impaired by alcohol, they have the perception that they are driving safely.  But marijuana impairment is fundamentally different than alcohol impairment. The reason a person under the influence of marijuana is an unsafe driver is because their ability to change strategy is affected. This, in combination with slow reaction time, is why driving high is so dangerous.  This inability to change strategy has to do with the Endocannabinoid receptors on the cerebral cortex.  So if the truck in front of the impaired driver has its left turn signal flashing, the impaired driver will assume the truck is turning left and might intend to pass the truck on the right. But if the truck turns right instead, the marijuana-impaired driver will have difficulty changing strategies and the accident is more likely to happen.  

There is no doubt that driving high is unsafe and one of the challenges with legalization will be to develop reliable tests to measure impairment.  I’ve seen articles about prototype marijuana breathalyzers and there are some interesting equivalents to the “walk the line” test that are under development.  The message that I want to convey to the students I work with is that smoking and driving is unsafe and should be just as taboo as drinking and driving. For more information about topics that are relevant to adolescents visit my website,
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