Traumatic brain injury is a major cause of death, disability, and long-term cognitive impairment. As with many other conditions, researchers have been exploring whether cannabis can help. Cannabinoids are known to be neuroprotective and this has prompted research exploring how cannabinoids may decrease the adverse outcomes of traumatic brain injury.
Endocannabinoids are naturally released as part of the body’s protective response to brain injury. Consuming tetrahydrocannabinol (THC) and cannabidiol (CBD) may help mimic the neuroprotective properties of endocannabinoids naturally released as a response to brain trauma.
There are some promising observational studies and preclinical research on the efficacy of cannabis for traumatic brain injury. However, the available data from clinical trials is less conclusive and has limitations.
As legal medical cannabinoids become more prevalent, further clinical trials should help to determine just how effective cannabis is for traumatic brain injury.
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How Cannabis Works on Concussions and Brain Trauma
The endocannabinoid system exists in all vertebrates and helps regulate crucial functions such as sleep, pain, and appetite. The human body produces its own cannabinoids, which modulate and activate its various functions, but as its name suggests, the endocannabinoid system can also be modulated and activated by cannabinoids found in the cannabis plant. Because the entire system was only discovered in the past 30 years, scientists still have much to learn about the myriad ways cannabis affects the human body.
Preclinical studies have focused on how to manipulate the endocannabinoid system to improve outcomes of traumatic brain injury. These studies have given us insights into how the endocannabinoid system is associated with the pathology of traumatic brain injury.
- A recent review of preclinical data on endocannabinoids and traumatic brain injury suggests that the endocannabinoids anandamide and 2-Arachidonoylglycerol (2-AG) naturally increase in response to brain injury.
- Research on rats and mice shows that when anandamide and 2-AG are administered after traumatic brain injury, this reduces brain damage and improves recovery.
- Data from test-tube and animal studies suggest that anandamide and 2-AG reduce the production of factors that promote brain damage like reactive oxygen species (ROS).
Based on these studies, it appears that the endocannabinoid system is involved in the recovery process after traumatic brain injuries in animal models.
Medical Studies on Traumatic Brain Injury and Cannabis
A three-year review found that THC was associated with a lower chance of death as a result of traumatic brain injury; mortality in the THC group was 2.4% and mortality in the non-THC group was 11.5%.
In one study on mice, THC reduced the release of glutamate, which is a common neurotransmitter in the brain. Excessive glutamate signaling is known to be one of the primary contributors to cell death following brain injury.
While data from reviews and preclinical trials show promise for cannabis, the results from clinical trials are mixed and also have limitations such as the exclusive use of synthetic cannabinoids.
In one randomized, double-blind clinical trial, researchers tested the effectiveness of the synthetic cannabinoid dexanabinol on patients with severe traumatic brain injury aged between 16-65. Both groups experienced similar adverse events that were typical of traumatic brain injury. The group treated with dexanabinol experienced 31% and 14% higher ‘good neurological outcomes’ after three to six months, respectively.
Another randomized placebo-controlled clinical trial also explored the effects of dexanabinol on severe traumatic brain injury. Results after six months showed no significant differences between both groups, and mortality rates did not differ significantly.
In yet another randomized controlled trial, researchers looked at the effects of the synthetic cannabinoid KN 38-7271 on the outcomes of early survival comatose patients after experiencing a severe traumatic brain injury. Survival rates were higher in the group given KN 38-7271 compared to placebo.
Overall, there is more positive than negative evidence regarding cannabis’s ability to decrease adverse outcomes of traumatic brain injury. However, more clinical trials are definitely needed before researchers can come to a concrete conclusion. Unfortunately, no ongoing or upcoming clinical trials looking at cannabis and traumatic brain injury can be found on ClinicalTrials.gov.
Potential side effects of cannabis use
In the majority of people, cannabis is well-tolerated. Common side effects of cannabis include drowsiness, fatigue, dry mouth, and appetite changes.
While cannabis has now become established as an effective medicine for many conditions, there are downsides worth mentioning.
- The psychoactive effects of THC can cause side effects such as memory impairment, anxiety, and euphoria.
- The development of psychosis is not unheard of, especially in genetically vulnerable individuals.
- Chronic and heavy cannabis use in one’s adolescent years has been associated with long-term cognitive deficits.
Cannabis addiction (also known as cannabis use disorder) occurs in approximately one in ten users. Heavy cannabis users who start young seem to be particularly susceptible to addiction, due to the plasticity of the developing brain.
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