CCPR: Clinicians working with adolescents have seen that kids are frequently using marijuana now—and stronger strains of it. What does this exposure mean for them? Is there any suggestion that marijuana use is affecting development?
Dr. Cermak: There is conclusive evidence that marijuana use, particularly in early adolescence, can affect brain development. The best research on this is probably the Dunedin Study done in New Zealand (Meier MH, Proc Natl Acad Sci 2012;109(40):E2657– E2664). Researchers did full neurocognitive testing on 13-yearolds and then followed them at various intervals up to age 38. They demonstrated that certain subpopulations had as much as an 8 point decrease in IQ from age 13 to age 38 with marijuana use. Now, it’s important not to over-interpret these results: Importantly, the only ones who demonstrated that much of an IQ change were those who began using at the very earliest ages of adolescence. Those who didn’t smoke until they were age 18, say, but then smoked continuously and heavily from then until age 38, did not show a decline in IQ. So, that’s the best evidence that youth who begin smoking quite early on are at the highest risk of adverse effects.
CCPR: Any other possible effects on cognitive functioning with early marijuana use?
Dr. Cermak: Most of the effect is on memory, attention, and executive function. With respect to this last domain, adolescents who have been abstinent for 28 days still can show some executive function impairment.
CCPR: What points would you make for clinicians working with children and adolescents?
Dr. Cermak: Delay, delay, delay. The more success we have getting kids to delay onset of use, the more protection we provide.
CCPR: How are adolescents who start smoking a bit later, say at age 16, likely to be affected?
Dr. Cermak: The primary effect for those who begin a little bit later in adolescence is on their education, which can be life-changing. Youth who smoke regularly during adolescence, even if they don’t start at age 13, are likely to be earning about two-thirds as much as the average person at age 30. That economic impact predominantly comes from interfering with education right at the point where the adolescent’s educational trajectory is being determined. If you spend a couple of years stoned and not paying attention to your education, then stop smoking and clear your mind, you’re still apt to go to a less rigorous college— or maybe not get into college at all—because of how poorly you did in the 10th and 11th grade.
CCPR: How do you think marijuana affects the ability of adolescents to mature normally?
Dr. Cermak: Everyone moving through adolescence must master numerous psychological developmental tasks in order to navigate their way from dependence on others to a place of independence early in adult life. Unfortunately, marijuana use often substitutes for the psychological work needed to achieve those goals.
CCPR: Can you give us an example?
Dr. Cermak: We all know that development of autonomy is essential. With marijuana, adolescents need only to light up to become a marijuana smoker, which, in many people’s minds, is a step toward autonomy. They may think, “I’m told not to do this; however, I do it, so I’m an adult. I’m making my own decisions.” And they join a subculture that is attractive in many ways, creating a sense of affiliation outside of the family. But it’s an affiliation based on a narrow characteristic: drug users who share the same habit. It doesn’t come from developing the capacity to have intimate relationships outside the family. So, kids think they’re achieving movement toward adulthood when, in fact, using marijuana is a substitute for the real psychological task.
CCPR: What are your thoughts about “amotivational syndrome”?
Dr. Cermak: I actually doubted the existence of this concept until recently. While it’s clear that a lot of daily users prefer their couch over anything else, I wasn’t sure one could measure motivation scientifically. However, recent work using brain imaging looked at the brain’s response to anticipatory reward (Martz ME et al, JAMA Psychiatry 2016;73(8):838–844). For regular marijuana smokers who are not stoned at the time they are being tested, the brain reward mechanisms respond less to the anticipation of monetary reward when compared to the response seen in non-marijuana smokers. This suggests that the reward mechanisms develop a narrow salience for marijuana-related experiences that can dominate other kinds of rewards necessary for a broader range of development.
CCPR: What else should clinicians know?
Dr. Cermak: There are two other pieces of research I think everyone treating adolescents should know about. One is work by Staci Gruber that offers good evidence that marijuana users are processing affective cues differently than nonusers (Gruber SA et al, Drug Alcohol Depend 2009;105(1–2):139–153). That fits with what I hear from many family members of regular smokers, which is that they lack a certain emotional presence. The other result is from research using the Iowa gambling task, which assesses real-life decision-making and risk-taking. Regular marijuana smokers are less deterred by the large losses and attracted to the large gains. This research shows that users are apt to stick with a strategy that trades lower overall payoff for higher short-term gain. It’s a perfect example of people not learning from their mistakes (Wesley MJ et al, Psychiatry Res 2011;191(1):51–59).