Opponents of marijuana legalization have been exaggerating the drug's side effects and risks for years. The 1936 American exploitation film Reefer Madness is a prime example. It is melodramatic and distorted anti-drug propaganda like this, supported by inconclusive and confusing scientific research, that have been used to provoke the unwarranted hysteria surrounding marijuana. But regardless of the stigma marijuana has incurred, its estimated that approximately 38% of Americans have tried the drug.
Still, a great deal of misinformation remains. In an effort to clear the air, we've debunked the 5 most unremitting myths about marijuana.
Myth #1: Marijuana makes people lazy.
Studies have not been able to distinguish marijuana-induced lethargy from general laziness. Looking at a group of 19 daily pot smokers, researchers found lower levels of dopamine in their brains than in those who had never lit up. Dopamine is a neurotransmitter directly linked to motivation and reward. Therefore, the study suggests marijuana use may lead to "amotivational syndrome," an unofficial condition described as chronic lack of motivation.
But the allegation remains uncertain since amotivational syndrome is just as likely to affect non-marijuana users as it does long-term smokers. A study published in the journal Psychology of Addictive Behaviors discovered amotivational syndrome plagues 5-6% of the entire population, both users and nonusers.
It's true that some pot heads are lazy, but so are many non-smokers. Researchers have found no significant differences between the groups' levels of productivity.
Myth #2: Marijuana causes brain damage.
A preliminary study published in The Journal of Neuroscience compared a group of 20 marijuana users to a group of 20 nonusers and noticed differences in their brains. The media ran with that information, insisting recreational marijuana use re-shapes users' brains and can even cause permanent damage.
However, the hype surrounding the report is unwarranted. According to Dr. Jodi Gilman, one of the authors of the Harvard Medical School/Massachusetts General Hospital study, their results were terribly misconstrued. Gilman says, "The conclusions were modest in the paper—we never say marijuana causes these changes. The media may have given that impression in headlines, but the study doesn't show causation." Instead, the report only shows correlation.
Study participants from both groups were hooked up to an MRI, and in the brains of the marijuana smokers, researchers found structural differences in the regions related to cognitive and emotional processing. "The main point is there are differences in the brains of these two groups," Gilman says. "The subtlety is we don't know if those differences are causal and relate to function or behavior."
There's no clear evidence whether marijuana changes brain structure or if people with certain brain structures are more prone to using marijuana.
Myth #3: Marijuana use leads to crime and delinquency.
Alcohol prohibition has taught that prohibition itself leads to crime, not the prohibited substance. A Norwegian study found that adolescents who use marijuana may subsequently participate in criminal activity but the majority of the activity seems to be confined to drug-specific crimes. Consequently, it is laws related to marijuana use, possession, and distribution that are to blame, not actually the drug itself.
An online journal dedicated to primary scientific research, PLOS ONE, published an article debating the effects of legalized marijuana on crime rate. Researchers found in states where medical marijuana was legalized, crime rates did not increase but rather remained the same and even decreased between the years 1990-2006.
In a similar study conducted in the United Kingdom, researchers found crime rates were actually reduced following the decriminalization of marijuana as police were free to pursue more serious offenders and criminals.
The rate of marijuana users does tend to be higher among convicted felons than non-offenders, but there is no direct evidence showing marijuana actually causes criminal behavior. It may simply be that criminals are just more likely to use marijuana.
Myth #4: Marijuana is addictive.
With the high addiction rate of other Schedule I Controlled Substances, the amount of concern regarding marijuana dependency is no surprise. But as this commonly cited study shows, less than 4% of Americans with a history of dependence are actually dependent on marijuana compared to the 24% dependent on tobacco and 14% on alcohol.
This research claims in order for a drug to be characterized as highly addictive, "there should be evidence that substantial numbers of users repeatedly fail in their attempts to discontinue use and develop use patterns that interfere with other life activities." Among the overall population of substance users, only 9% of marijuana users report to be hooked. That's well below the 32% and 15% of tobacco and alcohol users respectively who are addicted. Marijuana is significantly less habit-forming than even alcohol and tobacco and therefore not inherently addicting.
In a clinical study of marijuana tolerance and dependence, researchers did observe very mild signs of withdrawal in study participants after being abruptly cut off from high daily oral doses of THC, an equivalent of 15-20 joints per day. But a similar study found that when participants were allowed to manage their consumption rate, even high doses weren't followed by adverse withdrawals after a more gradual cessation of the drug. These studies suggest marijuana users are at a very low risk of developing dependency.
Myth 5: Marijuana is a gateway drug.
Marijuana is the most popular and available illicit drug. Therefore, people who use more harmful and less accessible drugs like heroin and cocaine are likely to have used marijuana first. A recent survey from the National Institute on Drug Abuse actually found that while marijuana use has increased among adolescents in recent years, the use of heroin, cocaine, and methamphetamines has all dropped.
New evidence suggests rather than a gateway drug, marijuana can veritably function as an "exit drug"—a terminus for helping people reduce their use of harder drugs by easing the adverse symptoms of withdrawal.
Alternatively, ardent drug use is most likely attributed to the adversity many addicts face in their youth. An associate professor of sociology at the University of New Hampshire, Dr. Karen Van Gundy, told CBS News "Whether marijuana smokers go on to use other illicit drugs depends more on social factors like being exposed to stress and being unemployed — not so much whether they smoked a joint in the eighth grade."