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Concussion is a traumatic brain injury or TBI. It occurs when an impact happens to the head causing the brain to suddenly accelerate within the skull with enough force that the fluid between the brain and the skull are insufficient to protect the brain from injury. Concussion injuries can range from mild to severe and both singular and repeated concussive events can result in death.
Common concussion symptoms include headache, a feeling of pressure in the head, temporary loss of consciousness, confusion, amnesia around the event that caused the injury, dizziness, ringing in the ears, nausea, slurring, delaying response to questions, being ‘dazed’, fatigue and vomiting. Other symptoms may be delayed such as concentration and memory complaints, irritability, personality changes, sensitivity to noise or light, and sleep disturbances. Symptoms may appear differently in children, who may become listless, irritable and may lose their balance easily. Children may also lose interest in food and their favourite toys and may cry ceaselessly.
If concussion symptoms are not noticed and treated quickly, other significant health problems and even death can occur. TBI is, even with current treatments, associated with significant morbidity (injury) and mortality (death).
Cannabinoids comprise 5 of the more than 60 active ingredients of the marijuana (cannabis sativa) plant. Cannabinoids include THC (the intoxicating agent of marijuana) and CBD (cannabinol). In particular, CBD and THC have received a lot of public attention in recent years for their potential health benefits. These substances have multiple biological effects and therapeutic applications in both the central and peripheral nervous systems and important in the area of neurology, CBD has important neuroprotective properties.
Many studies have demonstrated that there is a neuroprotective effect of cannabinoids. A 2014 study tried to determine whether there was a correlation between the presence of a positive test for THC (or marijuana) and mortality rates after a TBI. The study reviewed the registry data at a Level I trauma center for patients who sustained a TBI and had a toxicology screen for THC. Children under 15 and patients who had a nonsurvivable injury were excluded from the study. The patients were then divided into two groups, the THC+ group and the THC- group. The groups were then compared with respect to the mechanism of injury, the severity of the event, the disposition and mortality. Altogether 446 cases met all the criteria for the study. The THC+ group comprised 18.4% of the overall study. Overall mortality was 9.9% for the entire group but the mortality rate for the THC+ group was 2.4%.
This means that a THC+ toxicology screen was independently associated with survival after a TBI in adult patients. THC+ includes the presence of CBD. This study did not specifically review whether CBD could improve concussion symptoms other than mortality.
One of the biological effects of cannabinoids is the regulation of neuronal homeostasis and survival. This is because of a combination of a variety of effects that serve to preserve, rescue, repair and replace neurons and glial cells against insults (like concussion) that could potentially damage these cells. This is accomplished by the location of cannabinoid receptors.
There are cannabinoid receptors in the brain. When the brain is injured, the brain produces increased levels of endocannabinoids. This suggests that these substances play an important role in compensatory repair mechanisms (the ability of the body to repair itself or compensate for injuries). TBI like concussions currently remain rather refractory to present available drugs. This means that concussion symptoms may not be as well treated as they could be.
A review of preclinical studies conducted in 2017 designed to assess the therapeutic potential of cannabinoids, including CBD, to lessen TBI pathology. Specifically, these molecules and how they interact in the brain have shown promise in controlling or modulating the hallmarks of TBI pathology – cellular death, excitotoxicity, brain inflammation, breakdown of the blood vessels in the brain, cellular structure and remodeling.
The review also found that certain TBI induced behavioural deficits also respond to manipulation of the endocannabinoid system. These include learning and memory, neurological motor impairment, post-traumatic seizures and anxiety. This means that the endocannabinoid system is potentially “druggable” for the treatment of TBI symptoms. The review recommends fuller study of the changes in the endocannabinoid system that happen during a TBI to understand the role the entire system plays in TBI symptoms and pathology. This review further suggests continued and more specific study of cannabinoids, their neuroprotective properties, and how they may be used to further treat TBIs.
All of this means that cannabinoids like CBD appear to have a neuroprotective function when it comes to concussion injuries and other TBIs. More than this though, cannabinoids may well hold the promise the effective treatments for the symptoms and pathology that come after a TBI event.
A further study researched what is happening in the brain. When a TBI happens, harmful mediators are introduced into the brain environment. Glutamate, ROS and cytokines cause vasoconstriction, excitotoxicity, neuronal cell death and neuroinflammation. In turn these processes cause secondary damage and in the case of concussion, are responsible for most concussion symptoms. When endocannabinoids (part of the brain’s repair system) are present via the cannabinoid receptors, they encourage the production of stem cells (which can repair or replace other cells), increase differentiation migration, decrease the harmful effects of the Glutamate, ROS and cytokines. All of this reduces or ameliorates the secondary damage that is responsible for most concussion symptoms.
This study indicates that cannabinoid-based drugs can be an effective therapeutic solution for concussion and other TBI. Importantly, they appear to be able to significantly reduce the impact of a traumatic brain injury, including concussion symptoms but more importantly, they may significantly reduce the mortality rates post TBI.
Other Neurological Conditions and Cannabinoids
The potential neuroprotective qualities of cannabinoids on brain structures (neurons, glial cells and neural progenitor cells) shows promise for acute (like concussion and stroke) and chronic (think Alzheimer’s) neurodegenerative conditions. A review of studies in this area conducted in 2015 collected all of the experimental evidence available that support the idea that different cannabinoids may be neuroprotective in conditions like adult and neonatal ischemia, brain trauma (like concussion), Alzheimer’s, Parkinson’s, Huntington’s chorea and ALS. This collective review concluded that prompt clinical validations were required to validate cannabinoid-based medication for the treatment of all such conditions. The study noted that currently these conditions suffer from a lack of effective treatments to delay or stop the progression of disease. Despite the fact that few clinical studies so far with such medication failed to demonstrate beneficial effects.
In the case of ischemia (bleeding in the brain, stroke), studies have found that cannabinoids have a beneficial and neuroprotective effect not only in cases of localized bleeding but in cases of wider spread or global bleeding. Importantly, studies have shown that cannabinoids ameliorate the psychological symptoms of ischemia as well as the physiological symptoms.
The study noted above suggest that cannabinoid-based medications might serve as a new therapy to delay or arrest neurodegeneration in acute (sudden) and chronic conditions. They do this by normalizing glutamate homeostasis, reducing injury caused by oxidation, and/or reducing localized swelling. They also are possibly capable of activating certain response in cells to control the toxicity of protein aggregates.
Most of the studies reviewed, however, have been conducted on either animals or cellular models. Even the clinical trials on humans have focused on alleviating specific symptoms rather than fighting disease and injury.
The safety of cannabinoid medication has been demonstrated in previous studies though this needs more study. Given all of these results, the push should be on to approve THC and CBD based medications for use in clinical trials for acute and chronic neurodegenerative disease and injury and to take advantage of its neuroprotective properties in the treatment of such disease and injury.
Concussions are significant TBI, the outcomes of which can likely be dramatically improved with the provision of a cannabinoid treatment post injury. Concussion symptoms can therefore be significantly improved with appropriate cannabinoid-based medicines. However, at this time more study is required into the mechanisms of the brain’s production and use of endocannabinoids to repair itself and in reaction to both acute and chronic neurodegenerative conditions. CBD in particular should be more completely studied for its neuroprotective, anti-inflammatory and antioxidant effects.
Researchers encourage further study into cannabinoids, the mechanisms of endocannabinoids, to fully understand how to take advantage of the neuroprotective properties of THC and CBD. Their use to prevent mortality and reduce the impact of injury and disease is so far very promising.