The previous article talked about the non-genetic risk factors for becoming addicted to marijuana. According to research, genetic and non-genetic risk factors each account for 50% of the tendencies toward addiction. The most important non-genetic risk factor is age of first use. If the age of first use is in adolescence, the chance of becoming addicted to marijuana is much greater.
Serious effects of weed on the brains of adolescents
People Who Start Using Drugs at Age 21 or After Rarely Become Addicted
Here’s a statistic from Clean that sums up the importance of age of first use: “Nine out of ten people who become addicted began using before they were eighteen; a person who gets to age twenty-one without using is virtually certain never to do so (and only one in twenty of those who start using after the age of twenty-one become addicted).” This is an amazing statistic. Restated, it means that if we can manage to keep kids away from drugs until they are twenty-one, it’s “virtually certain” that we won’t have to worry about them ever trying drugs.
“The Impact of Drugs on [Adolescents’] Extremely Plastic Nervous System Is Dramatic”
We should note here that this statistic directly opposed an earlier opinion science held on this matter. In Clean, David Sheff states that we used to think that “the human brain is more or less fixed after a person is twelve or so.” This turns out to be wrong. Sheff adds, “Scientists now understand that the brain continues to develop…and…is most plastic—able to adapt and change—during adolescence and into one’s early twenties.” To sum it up, science sees it following way: “The impact of drugs on [adolescents’] extremely plastic nervous system is dramatic.” As evidence, researchers point to the terrible time doctors have detoxifying babies that have been born addicted to drugs. This is because “drugs have become an integral part of their nervous system.”
Dopamine Levels and Adolescent Drug Use
Developing brains are more malleable and responsive to drugs than brains no longer in the development phase. But the homeostasis system of the brain is just as responsive, so it makes severe nervous system changes in an effort to achieve homeostasis. Less responsive, fully developed brains can’t make these kinds of severe efforts at homeostasis. And highly-responsive brains make changes that tend to be more permanent. One of these changes can include a permanent deficiency in dopamine. As Sheff notes, “Early [drug] use may cause a permanent deficit of naturally circulating dopamine.”
The Brains of Adolescent Marijuana Users Work Harder
And there is specific evidence differences in the brain of adolescent marijuana users. Susan Taper, professor of psychiatry at the University of California at San Diego, says in Clean that “adolescent marijuana users use larger portions of their brain to complete the same task as non-smokers,” and adds, “Their brain is working harder than it should.” Research indicates that problems outside cognitive functioning are also damaged by early use of marijuana.
In Clean, Sheff makes the point the problems that occur with an adolescent’s psychological and emotional development are “inseparable” with the cognitive and brain chemistry issues. When someone starts using marijuana, development of social skills stops. This can be especially problematic for people who begin using in adolescence, a time when this type of development is in full swing. Though it’s not as measurable as cognitive damage, marijuana use in adolescents stunts emotional, psychological, social skills. In short, as David Sheff says, “Drugs—including marijuana—can wreak havoc on developing brains precisely at the time they’re supposed to be maturing.”