The Physiological and Neurological Dangers of Marijuana Use
Marijuana is a drug that has been popular for decades, but in recent years, more and more debate has risen about whether it is safe to use and whether it should be legalized across the United States. Many studies have been conducted that show the dangers that marijuana can impose upon users of the drug, in terms of physiological and neurological health.
A study published in the Journal of Immunopharmacology tested the effects of THC, the main component of marijuana that affects neurological function, on human natural killer (NK) cell function. The study found that THC “was inhibitory for NK activity against K562, a human tumor cell line at concentrations [as low as] 5 μg/ml when pre-incubated with the effector cells” (Specter et al., 1986). Furthermore, a study published by the American Society for Clinical Pharmacology & Therapeutics states that “prolonged delta-9-tetrahydrocannabinol (THC) ingestion produced significant heart rate slowing and blood pressure lowering in hospitalized volunteers. Impaired circulatory responses to standing, exercise, Valsalva maneuver, and cold pressor testing suggest a state of sympathetic insufficiency” (Benowitz et al., 1975). From this, it is clear that the THC in marijuana poses a threat to cellular and physiological health by inhibiting typical bodily functions.
Marijuana use can also have an impact on neurological health. A study published in the Oxford University Press Journal was conducted to determine the effects of long-term marijuana use on axonal fibre pathways and connections in the brain. The study found that “The fimbria network comprised a total of 7 1.6 stream-lines in users (meanstandard error) and 446.4 in non-users, an 84% reduction…[and] The commissural fibre comprised a total of 9 1.7 streamlines in users and 78 15.1 in non-users, an 88% reduction” (Zalesky et al., 2012). Therefore, it is clear that marijuana has the ability to reduce connectivity in brain tissue, and pose a hindrance to neurological function.
Intelligence is another facet that can be adversely affected by marijuana use. A study published in Proceedings for the National Academy of Sciences of the United States of America was conducted to test the neuropsychological decline in users of marijuana from birth to age 38. The study found that “study members who never used cannabis experienced a slight increase in IQ, whereas those…diagnosed with cannabis dependence at one, two, or three or more study waves experienced IQ declines of −0.11, −0.17, and −0.38 SD units, respectively. An IQ decline of −0.38 SD units corresponds to a loss of ∼6 IQ points, from 99.68 to 93.93” (Meier et al., 2012).
Change in IQ over time depending on marijuana use and dependence.
Moreover, a study published in the Neuropsychopharmacology journal was conducted to determine people’s likelihood to participate in risky behavior after using marijuana. The study found that after the third dose of marijuana, “subjects were more likely to persist on the risky option, whether winning or losing” (Lane et al., 2004). Therefore, marijuana has the ability to skew people’s rational perceptions and put them at risk by leading them to perform risky actions, regardless of outcome.
Marijuana has always been a popular drug, but recently greater public debate has arisen than ever before over whether it is safe and should be legalized in the U.S. While many argue that marijuana is safe, many studies show that it can have adverse effects on physiological and neurological health.
Works Cited
Benowitz NL, Jones RT. Cardiovascular effects of prolonged delta-9-tetrahydrocannabinol ingestion. American Society for Clinical Pharmacology & Therapeutics. Vol 18, p 287-297. 1975.
Lane SD, Cherek DR, Tcheremissine OV, et al. Acute Marijuana Effects on Human Risk Taking. Neuropsychopharmacology. Vol 30, p 800-809. 2005.
Meier MH, Caspi A, Ambler A, et al. Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings for the National Academy of Sciences of the United States of America. Vol 109, p E2657-E2664. 2012.
Specter SC , Klein TW, Newton C, et al. Marijuana effects on immunity: Suppression of human natural killer cell activity by delta-9-tetrahydrocannabinol. International Journal of Immunopharmacology. Vol 8, p 741-745. 1986.
Zalesky A, Solowij N, Yücel M, et al. Effect of long-term cannabis use on axonal fibre connectivity. Oxford University Press. Vol 135, p 2245-2255. 2012.
