CBD and its potential to treat Chronic Traumatic Encephalopathy (CTE)
Learn what CTE is and the impact CBD may have on it.
Traumatic brain injury is a major cause of disability and death in the US and its incidence is currently on the rise. Traumatic brain injury often leads to long-term consequences such as chronic traumatic encephalopathy (CTE). This chronic condition is crippling a significant percentage of former professional athletes and military members who have endured repetitive brain traumas during their career or service. The condition has been known for centuries, but a significant amount of new research started to emerge only during the last decade. Unfortunately, the current treatment options for CTE are extremely limited which is why research has turned towards new therapies.
Considering the major role of the endogenous cannabinoid system in the repair processes within the brain, a substantial amount of research has focused on the phytocannabinoids naturally found in hemp. Especially promising is cannabidiol (CBD) which lacks the psychoactive effects of the other popular cannabinoid - tetrahydrocannabinol (THC). In this article, we will reveal more about the exciting research that is on its way to understand whether or not CBD has the potential to treat chronic traumatic encephalopathy.
What is CTE and Traumatic Brain Injury
Chronic Traumatic Encephalopathy (CTE) is classified as a progressive neurodegenerative disease. According to the current literature, the biggest risk factor for its development is repetitive Traumatic Brain Injury (TBI). (1) Traumatic brain injuries include concussions, coup countercoup injuries, and diffuse axonal injuries. Axons are the nerve fibers that transmit the impulses from one nerve cell to another. When they are damaged by any TBI a cascade of events drives the pathology of cognitive and neurodegenerative issues.
According to TBI research, the initial trauma also damages blood vessels which results in a progressive inflammatory process. (2) The inflammation causes metabolic changes and triggers the release of the so-called tau proteins that entangle the brain and impair memory and cognition.
The symptoms of TBI begin years after the injuries occur and include problems with thinking, mood, behavior, and depression. Eventually, these symptoms progress into dementia. Diagnosis of the condition is possible with SPECT scan, but a definitive diagnosis is often made during an autopsy, unfortunately. The main pathological finding is atrophy of the brain.
Statistics reveal that every year approximately 70 million people worldwide sustain traumatic brain injuries. (3) However, we do not know the threshold of injuries required for CTE to occur. It is a common condition in contact sports such as boxing, martial arts, football, and soccer. It is also common among people who serve in the military. The risk of developing CTE increases with the number of years active in the sport and the
accumulation of concussive traumas. Another study from 2019 found CTE in 223 out of 266 deceased football players. (5) The scientists estimated that the risk of CTE increases with 30% for every year of football played. (4) Considering these debilitating effects on such a high percentage of former professional players and the lack of effective treatment, CTE has received increased national and scientific attention.
Role of the Endocannabinoid System in Brain Recovery
Traumatic brain injuries trigger specific metabolic changes, including the release of inflammatory mediators causing secondary damage. However, protective mechanisms are also activated. One of these protecting mediators is compound called 2-arachidonoylglycerol (2-AG) which is the most abundant endocannabinoid in the brain. This fact, as well as a large body of evidence from experiments, suggests that the endocannabinoid system (ECS) is a major part of the repair mechanisms of the brain. (5) When 2-AG was administered to mice with traumatic brain injury it decreased inflammation and edema while improving recovery. 2-AG triggers both CB1 and CB2 receptors in the brain – the receptors of endocannabinoid system.
A recent review from 2017 suggests that manipulation of the ECS might be promising in modulating neuronal cell death, inflammation, vascular damage, and remodeling. (6) Considering the fact that traumatic brain injury and the consequent CTE remain refractory to currently available treatments, this makes phytocannabinoids such as CBD a candidate with therapeutic potential given its activity on CB2 receptors in the brain and peripheral tissues.
Both CBD and THC have been studied for their neuroprotective and antioxidative effects, since the discovery of the ECS in the 1990s, and newer studies keep confirming them. (7) However, CBD might be more suitable as a modulator of the ECS than THC because of the possible negative effects of THC. Some studies have shown that the activation of CB1 receptors by THC might negatively affect short-term memory. (8)
One of the main ways CBD can stimulate repair in the brain after traumatic injuries is by modulating astrocyte activity, astrocytes provide metabolic and detoxification support for the brain(9). But while astrocytes can also activate an inflammatory cascade, CBD decreases the proinflammatory mechanisms of astrocytes. The main function of astrocytes is to support nerve cells, their axons, and the connections between them. Research shows that astrocytes also play a role in repairing the brain after traumatic injuries. (10) What they do is protect the healthy nerve cells from spreading injuries and increasing cell survival.
Current research on CBD shows potential for reducing CTE symptoms
A recent review from 2019 has provided a good summary of the options for CTE management. (11) Currently, the treatment of CTE shows that CBD is only supportive. Usually, patients receive a combination of non-pharmacologic and pharmacologic treatments aiming to improve their quality of life.
Behavior problems are common amongst patients with brain injuries, primarily anxiety and depression. These are related to changes in neurotransmitter levels, post-injury. Statistics show that over two-thirds of CTE patients receive narcotic analgesics and antidepressants. (12) However, these drugs can have serious side effects.
On the other hand, cannabis use has been anecdotally reported as extremely effective in reducing CTE symptoms including headache, nausea, insomnia, dizziness, agitation, and psychotic symptoms. (13) This in combination with the limited treatment options has propelled research towards investigating the potential of CBD.
Multiple studies have confirmed the strong anxiolytic properties of CBD. (14) It improves mood, reduces agitation and aggression, and provides antipsychotic and neuroprotective benefits. (15) However, the majority of CBD research specifically on brain injury and CTE is limited to animal studies. A 2012 study on mice has reported that CBD administration after brain injury resulted in “lasting neuroprotection, with the overall effect of promoting greater functional rather than histological recovery”. (16) In short, CBD reduced the severity of the injury and restored overall neurological function. A previous study on piglets published in Nature found similar results. (17)
More Interesting Research is on The Way
There is exciting high-quality research in humans underway which will reveal more about CBD as a potential treatment for CTE and traumatic brain injuries. The first one is an ongoing retrospective analysis of the effect of CBD on chronic pain related to concussions. (18) Preliminary results are already revealed and published in “Neurology”. They report over 80% of patients using CBD have significant improvement in symptoms such as mood, pain, and sleep.
Another ongoing investigation is a five-year study launched by University of Miami researchers. (19) They are investigating the combination of CBD and another drug (confidential) to treat TBI and CTE in humans. Their preliminary research in mice showed significant improvement in cognitive functions. The scientists believe that CBD will reduce post-injury headaches, brain inflammation, and other CTE symptoms.
Neeka Health Canada (NHC) has started the first double-blind human study on the effect of CBD in treating brain injuries. The study is investigating the efficacy of CBD-based therapies on CTE symptoms in former NHL (national hockey league) players. (20) The study will focus on symptoms such as PTSD, depression, and progressive dementia, among 100 previous NHL players.
The endocannabinoid system has many vital functions in the central nervous system, including the regulation of inflammatory and repair processes in the brain. Phytocannabinoids such as CBD allow for the modulation of this system and could provide a possible therapy option for conditions which are refractory to the currently available treatments.
So far, we cannot make any substantive claims because research is still new and most of the studies are performed in mice. However, there is a lot of exciting new research on the way which will shed more light on the possibilities that CBD will offer for treating CTE and other disorders associated with brain injury.