Traumatic brain injuries are extremely common in the United States, with the CDC estimating 2.5 million emergency visits related to TBI in 2014 alone. TBI can result in a wide range of symptoms depending on the type and severity of the injury, resulting in a complicated and unique outcome in each case. Recently, however, physicians and patients have started to use medical marijuana to help alleviate many of the issues caused by TBI. In this post we will look at what TBI is and the science behind the claims that medical marijuana can help people with TBI.

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What is Traumatic Brain Injury?

Traumatic brain injury (TBI) usually results from violent bumps, blows, or penetrating injuries to the head causing abnormal functioning of the brain. The most common causes of TBI are falls and motor vehicle crashes, making up nearly three quarters of all TBI-related hospitalizations. Risk is generally higher in young children and older adults with the highest rate of hospitalizations among people 75 years and older.

Due to the complicated nature of the brain, a broad spectrum of symptoms can occur. In more mild cases there may be loss of consciousness, dizziness, nausea, headache, and other symptoms. In severe cases, however, TBI can result in loss of consciousness for a prolonged period, seizures, slurred speech, and other serious problems. These issues can also be long lasting and present themselves long after the initial injury.

Research further suggests repeated and severe TBI can result in degenerative diseases, such as Alzheimer’s, Parkinson’s, and dementia. More information can be found on the Mayo Clinic website and the CDC website. The CDC also provides informational materials via Heads Up, which aims to educate readers on the different facets of brain injury.

How Can Medical Marijuana Help Those with TBI?

Brain injury and marijuana are not necessarily two things that would seem to go together. Some researchers, however, are showing that marijuana may have a beneficial effect on some brain injuries.

We’ve previously seen marijuana being used to lower pain in several cases [1][2], and this may help some people with pain related to previous TBI. One of the most common problems related to TBI are headaches and migraines. Marijuana has been shown to successfully reduce pain associated with several types of headaches and migraines [3]. Cannabinoids have also been used to fight inflammation, further providing relief to some TBI patients [4].

Other symptoms of TBI may also be attenuated by medical marijuana. Marijuana may be able to reduce seizures in some users [5], lower levels of nausea and vomiting [6], and fight other issues TBI may cause. In the cases of degenerative diseases possibly caused by previous TBI, marijuana may also help. Marijuana may increase the quality of life of those with Parkinson’s [7], Alzheimer’s, and dementia [8].

Beyond these uses, the endocannabinoid system has been shown to be a promising therapeutic target for those with TBI. We’ve previously seen some of the effects the endocannabinoid system can produce in the brain, going so far as to promote the growth of new cells in certain areas of the brain [9], so it may not be a big surprise that researchers are looking into more possible use cases.

The cell death caused by TBI begins immediately and can last for months following. This is a bad thing. There is research showing marijuana slowing this death in animal studies. Two studies in mice found that cannabinoid receptor agonists slowed both blood-brain barrier and neural cell degradation [10][11]. Further effects on the blood brain barrier have been documented, including reducing hypotension caused by toxic shock, which may help in cases of TBI [12].

Endocannabinoids also have protective effects against edema after brain injuries [13] and animal studies suggest that activation of a cannabinoid receptor is crucial to this [14]. These effects can also help protect against secondary injury caused by TBI.

In a study following four hundred and forty-six adult patients who had TBI, it was found that those who tested positive for THC had a statistically significant reduction in mortality rates [15]. One proposed hypothesis hinges on the slightly neurotoxic effects of THC at lower doses. The slightly damaging effect of the THC protects against the hugely damaging TBI by a sort of pre-conditioning [16]. There are fewer studies on the effects of CBD on TBI, but it does show some promise [17].

On the other hand, it is important to also discuss potential drawbacks. For example, the main cannabinoid researched particularly for treatment of TBI was HU211. In trials, HU211 did not show any long-term benefits [18][19]. The usual side-effects of marijuana use must also be considered, especially in an already at-risk population. Marijuana can lower reflexes and cause mental and behavioral changes, increasing the risk of injury. Some researchers also point out a possible increase in the development of psychosis in adolescents with TBI [20].


Research specifically linking benefits for those with TBI and marijuana are scarce, but there is promising evidence that it may be the case. Many studies show marijuana as having neuroprotective properties and some even show this following TBI. Research on long-term effects is also lacking and is desperately needed. It is important for physicians considering recommending marijuana to patients with TBI to weigh each case individually.