For good or ill, marijuana legalization has gained momentum in recent years. Alaska, Colorado, Oregon, and Washington have enacted legislation to regulate marijuana for recreational use, and 20 more states have laws allowing medical use1. However, considerable controversy remains regarding the health effects of marijuana use. Countless epidemiological studies, as well as studies using model organisms and cultured cells, have produced mixed results.   Many people are familiar with medical use of marijuana to treat specific diseases, such as epilepsy and AIDS; however, there are also several examples of potential health benefits of marijuana with regard to aging and age-related diseases.

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Could medical marijuana have applications to aging?

If smoking is bad for your health, how can marijuana use possibly be beneficial? Of course the act of smoking per se is harmful, but what is being smoked obviously makes a huge difference: multiple studies suggest that cannabis smoke is less carcinogenic than tobacco smoke2. Also, as in the case of tobacco, the active ingredients in marijuana (“cannabinoids” like THC—Tetrahydrocannabinol) can be administered via less harmful methods (via ingestion or vaporization) allowing the positive effects of cannabinoids to be realized without the drawbacks of smoking.

One theory of aging posits that the sum of all oxidation reactions determines an organism’s lifespan.   In fact, there is a clear correlation between an organism’s maximum age and the amount of oxygen it consumes 3. If we believe this theory, then we must also accept that ingesting any antioxidants could slow aging. Cannabis is a rich source of such compounds. This isn’t a coincidence: the surface of a cannabis plant is densely covered with trichromes, specialized cells that act as secondary metabolite factories to secrete a bouquet of antioxidant, antimicrobial, and (of course) psychoactive compounds. Several reports detail how cannabinoids produce neuro-protective effects due to their antioxidant capacity.

Additional potential age-related health benefits of cannabis consumption have been shown to result from the binding of Tetrahydrocannabinol (and other cannabinoids) to cell surface receptors CB1 and CB2. The CB1 receptor is primarily expressed in the brain, and the CB2 receptor is expressed primarily by cells of the immune system. Our bodies produce a handful of CB1/2 binding compounds endogenously. Many studies have examined how CB1/2 activation by endogenous or cannabis-derived molecules can be beneficial. In 2011, Mukhopadhyay, B. et al. reported in the journal PNAS that the CB1 receptor is necessary for liver regeneration after two thirds partial hepatectomy4. Several studies have demonstrated cannabinoids can induce apoptosis in cancer cells. Furthermore, an epidemiological study found an inverse association between type 2 diabetes and cannabis use, suggesting a potential protective effect5.

Of course, as with any drug, there are potential negative side effects. Smoking cannabis is positively correlated with the incidence of lung cancer6(although not as strongly as tobacco smoking), although obviously the benefits of cannabinoids can be realized through methods other than smoking. Another study claims that life-long cannabis use results in decreased IQ7 (although the effect may be rather weak and due to personality factors). Most worrying, however, for the possibility of widespread cannabinoid use is evidence suggesting the large number of neurological changes during puberty could be severely impacted by exogenous cannabinoids8. Even though it is difficult for retrospective studies to separate consequences correlated with cannabis use from common risk factors, most people would agree that the decision to medicate children with any drugs should not be taken lightly.

Lastly, cannabis consumption has the possibility of leading to poor diet (how else could Taco Bell possibly exist?), as well as significant legal problems for those not fortunate enough to live in a state where marijuana is decriminalized. Additional studies are needed to catalog completely the positive and negative results of cannabis use, but it is clear that, like other biologically active natural compounds, marijuana and cannabinoids derived from it offer potential for mitigating some effects of aging.


References:
1http://money.cnn.com/interactive/news/economy/marijuana-legalization-map/
2Melamede, Robert. “Cannabis and Tobacco Smoke Are Not Equally Carcinogenic.” Harm Reduction Journal 2 (2005): 21. PMC. Web. 18 Sept. 2015.
3 Miquel, J. An Update on the Oxygen Stress–Mitochondrial Mutation Theory of Aging: Genetic and Evolutionary Implications. Exp Gerontol. 1998 Jan-Mar;33(1-2):113-26.
4Bani Mukhopadhyay, Resat Cinar, Shi Yin, Jie Liu, Joseph Tam, Grzegorz Godlewski, Judith Harvey-White, Isioma Mordi, Benjamin F. Cravatt, Sophie Lotersztajn, Bin Gao, Qiaoping Yuan, Kornel Schuebel, David Goldman, and George Kunos. “Hyperactivation of anandamide synthesis and regulation of cell-cycle progression via cannabinoid type 1 (CB1) receptors in the regenerating liver.” PNAS 2011 108 (15) 6323-6328.
5Alshaarawy, Omayma; Anthony, James C. Brief Report: Cannabis Smoking and Diabetes Mellitus: Results from Meta-analysis with Eight Independent Replication Samples. Epidemiology. 26(4):597-600, July 2015.
6 Aldington S, Harwood M, Cox B, et al. CANNABIS USE AND RISK OF LUNG CANCER: A CASE-CONTROL STUDY. The European respiratory journal. 2008;31(2):280-286. doi:10.1183/09031936.00065707.
7 Madeline H. Meier, Avshalom Caspi, Antony Ambler, HonaLee Harrington, Renate Houts, Richard S. E. Keefe, Kay McDonald, Aimee Ward, Richie Poulton, and Terrie E. Moffitt. “Persistent cannabis users show neuropsychological decline from childhood to midlife” PNAS 2012 109 (40) E2657–E2664
8Schneider, M. Puberty as a highly vulnerable developmental period for the consequences of cannabis exposure. Addict Biol. 2008 Jun;13(2):253-63. doi: 10.1111/j.1369-1600.2008.00110.x.