Does Marijuana Kill Brain Cells?

by Ayotola Ogunsipe, edited by Christopher M. Cirino, DO MPH

As of 2021, marijuana is currently legal in eighteen of the United States; 15 additional states have decriminalized use. It appears that the bad reputation it has garnered over the years is gradually diminishing. The renewed interest comes amid marijuana’s possible benefits in chronic pain, multiple sclerosis, and cancer. However, marijuana still comes with downsides, such as anxiety, addiction, and risk of psychosis. 

This is a daily apple addressing the questions does marijuana kill brain cells. The article will review how marijuana affects the brain in the short and long term. The reader will learn how the drug alters the brain’s function and when to consider enough is enough. They may review another YHF article that goes into greater detail of the harms and benefits of marijuana.

Short Answer: Yes, studies support that it leads to reduced gray matter volume in certain parts of the brain after long-term use. The advice from YHF is to choose wisely and, if you are an adult and decide to partake, use responsibly. All substances are like double-edged swords.

person holding white a joint
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Marijuana and its medicinal use

The terms marijuana and cannabis describe the drug and are interchangeable. There are also slang terms for marijuana, including weed, pot, or ganja. The dried flowers and leaves of the Cannabis sativa plant impart the psychoactive effects from the compound delta-9-tetrahydrocannabinol (THC). The two traditional ways to use marijuana include smoking dried leaves as a joint of bong or ingesting THC in “edibles.” There are a variety of foods, including chocolates and gummy bears, that contain the substance. Additionally, there are a host of newer ways to take THC, including dabbing, vaping, pills, and oils.

For over 3000 years, marijuana herbalists have promoted it as an effective treatment for many ailments. Still, the focus has often been on its intoxicating effect and high abuse potential, particularly among young people. However, with its legalization in several states in the country, these health benefits have come to the fore. For instance, people with chronic pain frequently turn to marijuana for its analgesic effects. 

For cancer patients on chemotherapy, the cannabinoids derived from marijuana have been effective agents against nausea and vomiting. Furthermore, there is growing evidence that cannabinoids may effectively treat spasticity related to multiple sclerosis. 

Gray matter changes associated with atrophy have been found on functional MRI studies with chronic marijuana use.
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How Marijuana affects the brain

When vaped or smoked, marijuana releases THC into the bloodstream, with the level of this substance peaking within 30 minutes. While its effects tend to wear off within 1 to 3 hours, users often find it difficult to focus, learn or remember things even after 24 hours or more.

With long-term use, marijuana prevents the brain from creating memories or learning, an effect caused by its main psychoactive ingredient, THC. Heavy users of cannabis can form false memories, either recollecting events that never occurred or creating warped memories of events that did.

Age of use

For heavy smokers of pot, especially those that took it as a recreational drug during their teenage years, marijuana can leave permanent effects on the brain, with imaging tests of adolescent users showing a physical change in their brains. 

According to this research, those that smoked pot three times a day for at least four years had a smaller gray matter volume in the orbitofrontal cortex, which is the part of the brain responsible for addiction. The test also revealed changes in connectivity in the parts of the brain involved in learning, alertness, and memory. However, the images did not show this effect in the brains of every teenage marijuana user in the study. 

Reward system 

The reward system in the brain activates after you eat a delicious meal, have sex, or use an addictive drug. The activation leads to a surge in the amount of synaptic dopamine in the brain. Specifically, marijuana use affects the brain by rewiring the reward system, especially with frequent or long-term use of the drug. 

The effect of this rewiring is two-fold. First, users associate the drug intake with positive, rewarding feelings, which encourage them to want more of it. This behavior that can trigger dependence and addiction. Furthermore, marijuana use can also alter the brain’s natural response by hijacking the reward system. Users no longer find eating delicious food, winning some money, or having sex pleasurable.

Effects on the IQ

Research on intelligence suggests that the brains of people with above average IQs are wired differently. It appears that IQ is another factor that marijuana use affects. For instance, a New Zealand-based study observed that the habitual use of marijuana at a young age led to a loss of 6 to 8 IQ points by mid-adulthood. On the other hand, there was no reduction in IQ points for those who used marijuana at an older age.

Risk of psychosis

Psychosis is a condition that affects the brain causing an individual to lose touch with reality. While several reasons exist why people develop psychosis, there is evidence that marijuana use may trigger this condition, leading to the user’s first episode of psychotic illness or worsening symptoms in those with a pre-existing condition. Simply put, marijuana use can turn on the switch of psychotic illnesses. 

If you’re a marijuana user and wondering how much is too much, take note of your reactions to the drug. If you have hallucinations and other psychotic-like experiences after using, you may be prone to some form of psychotic illness. You should seriously consider avoiding the use of marijuana.

marijuana can intensify anxiety, depression, and exacerbate psychotic disoders and bipolar disorder.
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Marijuana Tolerance, Dependence & Withdrawal

After long-term use, the body responds differently to marijuana than it did before. One may need to take a higher dose to achieve the same effect, a condition known as tolerance. On the other hand, dependence occurs after someone uses regularly and has difficulty stopping. When a person does stop, they experience withdrawal symptoms. While dependence doesn’t necessarily equate with addiction, it is an indication that addiction is right around the corner. 

One could take a break from the drug to lower marijuana tolerance. THC takes approximately 21 days to leave the system, so your tolerance break must also be at least 21 days. 

Proper treatment and support systems can successfully manage marijuana addiction. Some medications, like baclofen and Vistaril, may reduce withdrawal symptoms. Buspirone, a serotonin receptor (1a) agonist (5-HT) and dopamine receptor antagonist (D2), reduced frequency and length of craving and decreased irritability and rate of depression. 

The use of behavioral treatments such as cognitive behavioral therapy, contingency management, and motivational enhancement therapy are adjuncts to kick the habit.

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