Does Marijuana Protect or Damage the Brain?

December 4, 2014 - By Dr. Malik Burnett and Amanda Reiman, PhD, MSW

Dear Doctors,

Please settle a bet. While watching football with my dad over Thanksgiving, the topic of concussions came up. I said that if players had access to marijuana then they would not have so many problems with head injuries because marijuana can protect the brain. My dad said that they would have more problems because marijuana hurts your brain. Who is right?

Debating in Maryland

Dear Debating,

Thank you for your question.

Indeed, there is a lot of conflicting information out there about the effects of marijuana on the brain. While the evidence about the cause and effect relationship of marijuana and cognitive functioning is still being gathered, there are some things that we do know about marijuana and brain function, as well as about the medical properties of marijuana in general, that can help answer this question.

When looking at the brain scans of adolescents who regularly use marijuana, we see something interesting. First, we note that certain regions of the brains of marijuana consumers are smaller than in non-consumers.

However, we also see that consumers’ brains have more connections formed than non-consumers. Now, what does this mean in terms of cognitive functioning? We do not know.

We do not know if having smaller brain regions and more connections makes a person more or less cognitively able, or whether it does not matter at all. When we look at people who have experienced injury to the brain, either from a trauma (like a concussion) or from a disease like Alzheimer’s, we see two interesting things about the effect of marijuana.

First, as in the case of trauma, there is a lot of inflammation that occurs, which affects cognitive functioning and neural connectivity. Marijuana has noted anti-inflammatory properties, which can help reduce brain swelling and therefore damage.

Similarly, diseases such as Alzheimer’s are also associated with brain inflammation and the destruction of neural pathways, the same pathways that seem to be more abundant in marijuana consumers. Research supports that marijuana can stimulate the repair and creation of pathways damaged by trauma and/or disease.

Let’s get back to your specific question (or rather debate) about marijuana use and football related injuries. Recently, there has been a push, partially by former NFL players, to soften the league’s marijuana use policies so that players can feel that medical marijuana is a viable option in states where it is allowed.

The HBO show “Real Sports with Bryant Gumbel” reported that 50-60 percent of players currently use marijuana regularly, mostly for pain relief. In response, the NFL changed their drug use policies and raised the level of allowed THC from 15 nanograms/liter to 35 nanograms/liter. This does open up the potential for medical marijuana use by professional football players in states where it is allowed.

However, tragedies such as the recent suicide of Ohio State football player Kosta Karageorge who had been complaining of dizziness and confusion related to head trauma, have more people asking if college football players should also be allowed to use marijuana for head injuries and other medical problems as a result of their time on the field.

In addition to the impact of years of being hit on the field, the impact of years of prescription pain medications can also take their toll. Brett Favre battled Vicodin dependence while healing from an injury.

So, who wins the bet, you or your dad?

I would say in the context of using marijuana specifically to treat traumatic brain injury, there is much promise (even the federal government holds a patent on marijuana for this purpose), and you win the bet.

However, there is some truth in what your dad is saying as well. For some populations such as adolescents and those vulnerable to mental health issues, the decision to use marijuana should be taken with care.

Use in moderation and with information and intention is what can truly maximize the benefits of the marijuana plant.

The Doctors

Dr. Malik Burnett is a former surgeon and physician advocate. He also served as executive director of a medical marijuana nonprofit organization. Amanda Reiman, PhD, holds a doctorate in Social Welfare and teaches classes on drug policy at the University of California-Berkeley.

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