If tobacco was not legal, and we knew the full scientific extent of its health impacts, would we legalize it today?
Not a chance. A substance that’s dangerously addictive and kills half the people who use it as directed? The FDA would never allow it. But we didn’t know the science hundreds of years ago, and tobacco became a common part of society. It’s too late to illegalize it.
Several states are considering legalization of marijuana. While the federal government has said it will not allow marijuana to be legal, state ballot initiatives notwithstanding, many Americans who would vote to legalize marijuana are doing so without knowing – or without believing – the science about the drug.
While we don’t know the full extent of marijuana’s impacts, we know enough to declare it harmful. Research over the last two decades has dramatically enhanced our knowledge about marijuana.
Here’s a sample of what we know, and the research that shows it. Don’t believe me, though. Read the research for yourself.
Marijuana is linked to a lot of health problems:
- Hall W, Degenhardt L. Adverse health effects of non-medical cannabis use. Lancet, 2009. “The most probable adverse effects include a dependence syndrome, increased risk of motor vehicle crashes, impaired respiratory function, cardiovascular disease, and adverse effects of regular use on adolescent psychosocial development and mental health.”
It harms the brain, particularly the adolescent brain:
- Medina KL, et al. Neuropsychological functioning in adolescent marijuana users: subtle deficits detectable after a month of abstinence. Journal of the International Neuropsychological Society, 2007. “… Even after a month of monitored abstinence, adolescent marijuana users demonstrate subtle neuropsychological deficits compared with nonusers… Frequent marijuana use during adolescence may negatively influence neuromaturation and cognitive development.”
- Zalesky A, et al. Effect of long-term cannabis use on axonal fibre connectivity. Brain – A Journal of Neurology, 2012. “… Long-term cannabis use is hazardous to the white matter of the developing brain.”
Marijuana smoke harms the lungs:
- Tetrault J.M., et al. Effects of cannabis smoking on pulmonary function and respiratory complications: a systematic review. Archives of Internal Medicine, 2007. “Long-term marijuana smoking is associated with increased respiratory symptoms suggestive of obstructive lung disease.”
And it contains carcinogens:
- Evidence on the carcinogenicity of marijuana smoke. Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 2009. “…There is some evidence from studies in humans that marijuana smoke is associated with increased cancer risk… the similarities in chemical composition and in toxicological activity between marijuana smoke and tobacco smoke, and the presence of numerous carcinogens in marijuana (and tobacco) smoke, provide additional evidence of carcinogenicity…”
It’s linked to mental illness, especially schizophrenia:
- Moore TH, et al. Cannabis use and risk of psychotic or affective mental health outcomes: A systematic review. Lancet, 2007. “…There is now sufficient evidence to warn young people that using cannabis could increase their risk of developing a psychotic illness later in life.”
- Large M., et al. Cannabis use and earlier onset of psychosis: a systematic meta-analysis. Archives of General Psychiatry, 2011. “We found that the use of cannabis and other illicit substances was associated with an earlier age at onset of psychotic disorders… The results of this study confirm the need for a renewed public health warning about the potential for cannabis use to bring on psychotic illness.”
- Arseneault L, et al. Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study. British Medical Journal, 2002. “Using cannabis in adolescence increases the likelihood of experiencing symptoms of schizophrenia in adulthood.”
Marijuana use by drivers doubles the risk of car crashes:
- Asbridge M, Hayden JA, Cartwright JL. Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis. British Medical Journal, 2012. “…Risk of a motor vehicle collision while driving under the influence of cannabis was almost twice the risk while driving unimpaired.”
No matter what anybody says, marijuana is addictive:
- Budney AJ, Moore BA. Development and Consequences of Cannabis Dependence. Journal of Clinical Pharmacology, 2002. “The past 10 to 15 years of clinical and basic research have produced strong evidence demonstrating that cannabis can and does produce dependence… Treatment seeking for marijuana dependence has increased almost twofold over the past 10 years.”
- Wagner FA, Anthony JC. From first drug use to drug dependence; developmental periods of risk for dependence upon cannabis, cocaine, and alcohol. Neuropsychopharmacology, 2002. “For those who used marijuana at least once, the estimated cumulative probability of becoming dependent on marijuana was 10%.”
- Treatment Episode Data Set (TEDS): 2009 Discharges from Substance Abuse Treatment Services, DASIS. Substance Abuse and Mental Health Services Administration. Office of Applied Studies, 2009. “Marijuana was the most common illicit drug responsible for treatment admissions… accounting for 16 percent…”
And finally, a big problem for our high-tech, innovation-based economy is that marijuana, frankly speaking, makes you stupid:
- Meier et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences, 2012. “Persistent cannabis use was associated with neuropsychological decline broadly across domains of functioning, even after controlling for years of education.”
- Fergusson DM, Boden JM. Cannabis use and later life outcomes. Addiction, 2008. “High levels of cannabis use are related to poorer educational outcomes, lower income, greater welfare dependence and unemployment and lower relationship and life satisfaction.”
- Macleod J, et al. Psychological and social sequelae of cannabis and other illicit drug use by young people: A systematicreview of longitudinal, general population studies. Lancet, 2004. “Fairly consistent associations were noted between cannabis use and both lower educational attainment and increased reported use of other illicit drugs.”
- Ellickson PL, Martino SC, Collins RL. Cannabis use from adolescence to young adulthood: Multiple developmental trajectories and their associated outcomes. Health Psychology, 2004. “… Early high [marijuana] users fared significantly worse than all other groups on overall health and yearly earnings and had the lowest educational attainment of all other groups …”
The point is this: We’re learning more and more about the impacts of marijuana on disease, mental health, car crashes and education, and it doesn’t look good. We’ll learn more as research continues.
Marijuana may not be as dangerous as tobacco or alcohol, but that’s no reason to legalize it. We already have two harmful, legal drugs in tobacco and alcohol. Why increase the death, disease, disability and economic damage they cause by adding a third one?