By Loren DeVito, PhD, Staff Writer for Terpenes and Testing Magazine and Extraction Magazine
The surge in cannabis interest over the last few years has significantly chipped away at long-held stereotypes of what a typical cannabis consumer is really like. Often portrayed in movies and media as slow or lazy, the modern cannabis consumer has sophisticated preferences for CBD, THC, or variations in CBD:THC formulas and incorporates their use appropriately into their very functional lives. However, the one stereotype that remains is one that is backed by some pretty consistent evidence – the calming effect of cannabis. In fact, cannabidiol (CBD) users cite anxiety as one of the top reasons for consumption. 
While different cannabis cultivars provide varying degrees of stimulation and relaxation, many who use cannabis enjoy its tranquil effects. It might surprise you then to learn that cannabis has actually been associated with the direct opposite behavioral effect – aggression.
At first blush, this seems like another scare tactic raised by prohibitionists that want to maintain the plant’s illicit status. However, several studies support the link between cannabis and aggression – in fact, some have even indicated that cannabis use may be linked to violent behavior [2,3] So before waving this off, let’s take a look at some of this evidence and try to better understand its basis in the brain.
Aggressive behavior is deeply rooted within “older regions” of the brain, or those that emerged earlier in evolution. These regions include the almond-shaped structure called the amygdala that regulates emotional behaviors.  Within this system, the brain chemical messenger serotonin plays an important role in modulating aggressive behavior.
While much of this evidence has come from work in pre-clinical models, data indicate that lower levels of serotonin are associated with higher levels of aggression and impulsivity.  This effect makes sense, in theory, considering that certain types of anti-anxiety and anti-depressant medications are designed to increase serotonin, thus increasing calm.
So how does cannabis affect serotonin? Before that question can be adequately addressed, it is important to recognize that cannabis consists of a wide array of cannabinoids and terpenes, each of which contains unique chemical properties that affect the brain and body in different ways. Therefore, specific behavioral effects are often correlated with the chemical profiles of unique cannabis compounds.
THC has been shown to reduce serotonin production, whereas CBD mediates anti-depressant effects by stimulating serotonin [6,7]. And a recent study found that people who have a certain type of serotonin receptor gene are at greater risk of aggressive behavior after exposure to THC, based on an experiment of animal models with the affected gene . However, in this same study, the animal models without the affected gene displayed less aggressive behavior after exposure to THC.
Although greater research is needed, these results suggest that THC could be linked to aggressive behavior but that this effect may vary depending on genetic differences related to the serotonin system. This study, among others, also shows that the potential relationship between cannabis and aggression is quite complex and can likely be attributed to multiple factors.
Of course, associations between any substance and aggressive behavior should be taken seriously. But it’s important to remember that not all cannabinoids (and terpenes) produce the same effects. And the more we learn about their differences, the better informed cannabis users will be about which cultivators and products are best suited for their needs.
As always, be a savvy cannabis news consumer and always, always apply a critical eye to media stories.
- Corroon, J., Phillips, J.A., “A Cross-Sectional Study of Cannabidiol Users”, Cannabis Cannabinoid Res, 2018, Volume 3, pg. 152-161.
(impact factor: N/A; cited by: 6)
- El Marroun, H., Hudziak, J.J., Tiemeier, H., et al., “Intrauterine Cannabis Exposure Leads to More Aggressive Behavior and Attention Problems in 18-Month-Old Girls”, Drug Alcohol Depend, 2011, Volume 118, pg. 470-474.
(impact factor: 3.322; cited by: 60)
- Schoeler, T., Theobald, D., Pingault, J.B., et al., “Continuity of Cannabis Use and Violent Offending Over the Life Course”, Psychol Med, 2016, Volume 46, pg. 1663-1677.
(impact factor: 6.159; cited by: 18)
- Lane, S.D., Kjome, K.L., Moeller, F.G., “Neuropsychiatry of Aggression”, Neurol Clin, 2011, Volume 29, pg. 49-vii.
(impact factor: 1.736; cited by: 70)
- da Cunha-Bang, S., Mc Mahon, B., Fisher, P.M., Jensen, P.S., Svarer, C., Knudsen, G.M., “High Trait Aggression in Men is Associated with Low 5-HT Levels, as Indexed by 5-HT4 Receptor Binding”, Soc Cogn Affect Neurosci, 2016, Volume 11, pg. 548-555.
(impact factor: 3.5; cited by: 16)
- Moranta, D., Esteban, S., García-Sevilla, J.A., “Differential Effects of Acute Cannabinoid Drug Treatment, Mediated by CB1 Receptors, on the In Vivo Activity of Tyrosine and Tryptophan Hydroxylase in the Rat Brain”, Naunyn Schmiedebergs Arch Pharmacol, 2004, Volume 369, pg. 516-524.
(impact factor: 2.238; cited by: 53)
- Sales, A.J., Crestani, C.C., Guimarães, F.S., Joca, S.R., “Antidepressant-like Effect Induced by Cannabidiol Is Dependent on Brain Serotonin Levels”, Prog Neuropsychopharmacol Biol Psychiatry, 2018, Volume 86, pg. 255-261.
(impact factor: 4.185; cited by: 3)
- Montalvo-Ortiz, J.L., Zhou, H., D’Andrea, I., et al., “Translational Studies Support a Role for Serotonin 2B Receptor (HTR2B) Gene in Aggression-related Cannabis Response”, Mol Psychiatry, 2018, Volume 23, pg. 2277-2286.
(impact factor: 13.204; cited by: 2)
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