Cannabis and CBD Research
Current research points towards cannabinoids serving as a neuroprotectant, and clinical trials are looking at CBD alone and CBD+THC for concussions. Findings also indicate that CBD and THC may be effective for pain management, anxiety, and insomnia, all of which are common symptoms of concussions and persistent post-concussive symptoms.
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Please read our Cannabis Health & Safety page.
Cannabis: There are numerous contraindications to be aware of for cannabis (marijuana) because of its THC content. Cannabis can interact with other medications, especially blood thinners. Federal agencies advise against using cannabis while pregnant or nursing. Check your state guidelines and talk to a medical professional before using these products. People with brain injuries may be more vulnerable to substance abuse, including abuse of marijuana.
CBD: There is a consensus that CBD (cannabidiol) “has a good safety profile.” CBD products are made from hemp and contain no more than 0.3% tetrahydrocannabinol (THC).
Some research focuses specifically on CBD (cannabidiol) which is not nonpsychoactive, and other research focuses on cannabis (marijuana), with various ratios of CBD and THC (tetrahydrocannabinol).
CBD products are extracted from hemp plants and the finished product must contain less than 0.3% THC.
We use the term medical cannabis (or medical marijuana) because that is what is being used in research studies. The critical point is that where marijuana is legal, either as medical marijuana or recreational marijuana, the products are regulated and you can purchase marijuana with specific ratios of CBD to THC.
Clinical Trials – CBD for concussions
Researchers in the U.S., Canada, and Australia are investigating the efficacy of CBD (cannabidiol) for the acute stage of concussion (when the injury is new) and for persistent post-concussive symptoms.
As of February 2022, a research team in Canada will be studying the efficacy of CBD and THC for concussions; the NFL awarded the research team $500,000 for this study.
In the United States
The University of Miami
An ongoing study on cannabinoid treatment for concussion is being done by the University of Miami which received a $16 million grant for the research. The study is a five-year, three-stage study that will “assess the effectiveness of a new cannabinoid-based pill to treat concussion injuries. This partnership aims to propel this research and potential treatment forward by using two classes of drugs in a combination that scientists believe will reduce brain inflammation and the immune response.”
As reported in UHealth in July 2018, the “findings of a pre-clinical pilot study were recently released, and they show that the combination therapy improved the cognitive functions of animals, compared with those treated with a single vehicle. In addition, there were no adverse effects from either the combination therapy or the individual components.”
The cannabinoid combination therapy is made up of CBD (cannabidiol) and Dexanabinol (HU-211) which is a synthetic cannabinoid that is an “anticonvulsant and neuroprotective, and is widely used in scientific research as well as currently being studied for applications such as treating head injury, stroke, or cancer.” The medicinal CBD for the study is sourced from BOL Pharma.
Phase 2 of the study is currently underway. The University of Miami is testing the cannabinoid-based pill on a small pilot study with people, including “a control group and two groups of TBI patients, acute and chronic.” More information can be found on our blog post, an interview with Dr. Hoffer. Dr. Hoffer had planned to transition to human clinical trials and file the treatment with the FDA in early 2021, but this was likely delayed by the Covid-19 pandemic.
Dr. Hoffer began a new study in February 2020 to research if “using a pill form of cannabidiol (CBD) and the psychedelic drug psilocybin effectively treats and possibly prevents symptoms of two conditions that commonly occur together: mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD)… Up to 40% of people impacted by mTBI [or TBI] also suffer from PTSD,” according to a University of Miami press release.
The University of Regina (Saskatchewan Province, Canada)
In February 2022, the NFL awarded the University of Regina $500,000 to “try to optimize the formulation of cannabinoids such as tetrahydrocannabinol (THC) and cannabidiol (CBD) for pain management in those suffering from post-concussion syndrome and chronic pain, and for a neuroprotective treatment for concussions.”
The U of R study will be led by Patrick Neary, who “expects their CBD/THC formulation to show significant and positive changes to the brain that will reduce pain and use of prescription medications, such as opioids, and reduce concussions during athletic competition. It will be “really exciting” to see whether the formulation they’re working on can reduce the incidence and/or the severity of concussions, he said.
Neary said when a person gets a concussion, there are chemical changes that are occurring in the brain to try and help it rehabilitate and recover from the trauma that it’s gone through. With the disruption in the cells in the brain, there will often be an influx of more chemicals than are needed initially and that creates inflammation, he said.
‘We know that CBD is anti-inflammatory, so it can help to reduce the inflammation while still allowing the brain to recover from those good chemicals that are coming in,’ he said. ‘So that’s the whole premise here. Can we use CBD? I believe we can.’”
Phase 1 will be “dedicated to figuring out the optimal formulation and amount of CBD athletes doing resistance training can take on a daily basis to treat inflammation.”
Phase 2 will “occur during football season, will have some players from the participating universities take the new optimal formulation and compare it against a placebo group to study its impacts.”
Phase 3 “will look at using a combination of CBD, tetrahydrocannabinol (THC) and nutritional supplements to reduce prescription pain medications, particularly opioids.”
NEEKA Health Canada
A new study led by NEEKA Health Canada will “test if CBD-based therapies can reduce the severity of post-concussion brain disorders in former NHL players.” The National Hockey League Alumni Association and Canopy Growth Corp. (a cannabis and hemp company) are partnering with NEEKA for the clinical research; approximately 100 former players will be enrolled in the randomized, double-blind study. Researchers hope to finish the study by the end of 2020 according to an article in Green Entrepreneur.
The medical cannabis company Impression Healthcare began a new clinical trial in mid-2020 to access its new cannabinoid formula IHL-216A on “its ability to protect the brain against the main injury mechanisms which cause cell death and other negative consequences in the days and weeks following head trauma.” Impression will test IHL-216A with in-human and animal trials.
Up to 50 Australian MMA fighters who “receive head knocks and show symptoms of moderate to severe head concussions” will participate in the study. Participants will either receive IHL-216A or a placebo. The effectiveness of the CBD formula will be tested by participants’ baseline neurocognitive tests, which will be repeated throughout the study in both the experiment and placebo groups, and EEG and blood biomarker assessments. Impression Healthcare hopes to have IHL-216A fully approved for market by 2024.
Research indicates medical cannabis improves concussion symptoms
A study published in Brain Injury in October 2019 found that even though cannabis use didn’t affect concussion recovery time, cannabis use was associated with a lower symptom burden in the third and fourth weeks after injury. See our blog post, Study shows cannabis use decreases symptom severity after a concussion.
A December 2018 study in the journal Neurology indicates that medical cannabis (marijuana) helps concussion patients with concussion symptoms, especially pain, mood, sleep, and quality of life. The study also specifies the optimal forms of medical cannabis for the patients in the study, in terms of rations of CBD to THC, and methods of intake, such as a tincture (oral) or a vapor pen (inhaling). Read more in our blog post, Study finds medical marijuana improves concussion symptoms.
CBD May Protect Against and Relieve Brain Injury Symptoms
Researchers also have been conducting studies to learn more about brain injuries, so they can understand the causes and develop new, more effective treatments. One brain injury treatment that is showing promise is cannabidiol, or CBD, which is a non-intoxicating cannabinoid molecule produced by cannabis.
What is a brain injury?
Traumatic brain injury (TBI) is a condition that occurs when a head injury, such as a bump, blow, or jolt, causes your brain to slam into the inside of your skull, which results in brain damage.
When your brain is injured, it releases neurotransmitters and chemicals that cause inflammation, blood vessel injury, chemical imbalances, tissue damage, and cell death. These brain responses are called a “secondary injury cascade” and are responsible for many of the neurological problems associated with TBI.
Although a severe TBI can be deadly or cause lifelong complications, even a mild TBI — which is commonly called a concussion — can cause symptoms that can last for days or weeks.
Repeated TBIs can cause a buildup of Tau protein, which can lead to a degenerative neurological condition called chronic traumatic encephalopathy (CTE). CTE can have a devastating impact on individuals and their families because it can cause a variety of symptoms that affect memory, emotions, behavior, movement, and mental functioning.
CBD May Offer Neuroprotective Benefits
In 1998, researchers published the results of a study on rats that demonstrated the neuroprotective benefits of CBD and tetrahydrocannabinol (THC), which are two of the cannabinoids found in cannabis.  Although more research is required to fully understand the neuroprotective effects of CBD, recent studies have shown that CBD activates the cannabinoid receptors in your brain that are part of your body’s natural endocannabinoid system.
A 2011 study of mice found that endocannabinoid levels are elevated during and after a TBI, which suggests that the endocannabinoid system plays an important neuroprotective role. 
Other animal studies also have shown that activating the cannabinoid receptors in your brain may help to limit nerve cell damage and promote healing by enhancing blood flow to the brain.  In a 2002 study, researchers found that mice that were genetically engineered to lack CB1, a cannabinoid receptor found in the brain, had more severe brain damage and cognitive deficits after a TBI when compared to mice that had the CB1 receptor.
Activating another cannabinoid receptor in the brain, called CB2, has been shown to promote the creation of new brain cells, as well as regulate inflammation after brain injury. A 2014 animal study found that mice that were genetically engineered to lack a CB2 receptor had worse outcomes after TBI when compared to mice that had a CB2 receptor. The study also found that the lack of a CB2 receptor impaired the creation of new brain cells.
And, CBD may also affect your glial cells, which insulate your neurons and facilitate your brain’s immune response after injury. Research shows that CBD seems to have the strongest effect on two types of glial cells: astrocytes and microglia. A 2017 animal study showed that CBD suppressed the activity and swelling caused by astrocytes;  another 2017 study showed that stimulating cannabinoid receptors in the brain suppressed inflammation caused by microglia in rats.
The Benefits of the “Entourage Effect”
Because full-spectrum CBD contains a variety of phytocannabinoids, it produces an “entourage effect” that engages both the CB1 and CB2 receptors in the brain — as well as other cannabinoid and non-cannabinoid receptors throughout your body — for maximum neuroprotective and overall health benefits.
Although further research is needed, some studies suggest that when CBD is used shortly before or within 12 hours of a brain injury, it may help to prevent or limit the damage that occurs after a TBI during the secondary injury cascade.
Anecdotal Evidence and Research Support CBD Use for TBI and CTE
Although CBD has shown promise for brain injury treatment in the research lab, anecdotal evidence also is strong — especially among some former professional athletes in sports with a high risk of head injuries, such as boxing and football.
Many professional athletes have spoken out about the benefits of CBD for the treatment of TBI and CTE symptoms, saying that it helped to regulate their mood, improve physical function, and reduce or eliminate their use of prescription painkillers and other medications.
Unlike many prescription pain medications, CBD is non-addictive and will not lead to overdose. CBD does not cause side effects and will not result in increased tolerance that requires higher doses to achieve the same effect. CBD also can be used to treat other health conditions that are common in athletes, such as chronic pain, anxiety, and insomnia.
But although anecdotal evidence suggests that CBD may be safe and effective for professional athletes, it also may show promise for the treatment of TBIs caused by youth sports, falls, car accidents and military combat injuries. And, researchers are investigating CBD as a potential treatment for other conditions that affect the brain, including Alzheimer’s disease, Parkinson’s disease, stroke, and HIV-associated dementia.
Researchers are hoping to conduct further studies on CBD and how it can be used to treat TBI and CTE, as well as develop dosing and safety recommendations for CBD use. But in the meantime, many people who have experienced TBI or have been diagnosed with CTE are using CBD to treat the symptoms of their condition — often with life-changing results.