Marijuana and Your Brain


  • Marijuana is a psychoactive substance that affects the brain in a number of ways
  • Regular users and first-time users report different effects
  • The effects of marijuana on the brain depend on dosage, tolerance and concentrations of THC and CBD
  • THC is known to be psychoactive, whereas CBD is known to counter the psychoactive effects of THC
  • The psychoactive effects of marijuana range from disruption of memory to antidepressant activity
  • Users should weigh the benefits of marijuana against the drawbacks before using marijuana for medical or recreational purposes – Regular marijuana users are well aware of the psychoactive effects of marijuana, yet many struggle to give an accurate description of the ‘high’ that they experience. As a result, the effects of marijuana on the brain continue to be a hotly debated topic. Luckily, an accumulation of scientific evidence over the past few years has provided experts with insight into how marijuana affects the brain.
When marijuana is ingested, cannabinoids such as THC and CBD enter the user’s blood stream and bind to receptors in various parts of the human body, including the brain. When marijuana is smoked, the effects of cannabinoids can be felt within a matter of seconds. Such quick and potent action has lead many to wonder what exactly marijuana does to the brain and whether regular use of the substance is safe in the long-run.

Marijuana Use: Common Effects

It’s no wonder that marijuana users experience difficulty in describing the ‘high’ associated with marijuana use, as research shows that marijuana can affect a wide range of neurological functions. Interestingly, these effects seem to be both positive and negative and tend to vary from user to user.

The beneficial effects of marijuana are more often reported by regular users, who describe feelings of euphoria, relaxation and diminished stress. On the other hand, it is common for first time users to report feelings of anxiety, dizziness, confusion and psychosis. Experts suggest that differences in tolerance and dosage may be the explanation for why regular users and non-users experience such opposite effects.

On top of that, research has shown that the concentration of specific compounds in marijuana can have a dramatic impact on the way the brain is affected.

Cannabinoids: THC and CBD

In order to understand how marijuana affects the brain, it is important to identify the various components of marijuana.

Marijuana is rich in a group of chemicals known as cannabinoids. Although researchers have identified over 60 different cannabinoids that naturally occur in marijuana, THC and CBD are the only cannabinoids present in high concentrations.

THC is the most psychoactive cannabinoid of the two, as it binds to the largest number of cannabinoid receptors that are found in the brain. On the other hand, CBD has been shown to have the opposite effect by acting to reduce the psychoactive effects of THC. Experts believe that strains of marijuana that contain a balance of CBD and THC concentrations may be ideal for medical use by posing less risk of unwanted side-effects to medical marijuana users.

Unfortunately, marijuana that is sold on the illegal drug market is catered to recreational users and, as a result, tends to possess a major imbalance of cannabinoids in favor of higher THC concentrations. THC is almost solely responsible for the ‘high’ that marijuana users experience and has been the primary subject of research regarding the effects of marijuana on the brain.

Memory and Cognition

One of the most alarming effects of marijuana is its disruption of memory and other cognitive processes. Indeed, studies confirm that THC has a temporary, yet strong influence on both short and long term memory. More specifically, THC is believed to impair the function of short-term memory and the consolidation of short-term memory into long-term memory, which explains why regular users tend to forget certain things that happened to them while they were high.

However, research shows that THC does not affect the recollection of previous memories, which means that, unlike alcoholics, marijuana users will not forget their name or address no matter how high they might be. Research has also shown that CBD can prevent the memory-impairing effects of THC, suggesting that a well-balanced strain may be the key to reducing the memory impairments associated with marijuana use.

Research also suggests that marijuana use can have a negative impact on cognitive performance. A study conducted in 2005 found that current marijuana users performed worse than nonusers in overall IQ, processing speed and memory tests. On the other hand, the study found that former marijuana users did not show any signs of cognitive impairment. Although not entirely conclusive, many experts believe that long-term abstinence (e.g. at least 1 month) from marijuana use can reverse the cognitive impairments that are associated with regular use of marijuana.

Anxiety and Depression

Marijuana use and anxiety seem to have an interesting relationship, as both increased and decreased anxiety are commonly associated with marijuana. Studies suggest that THC’s effect on anxiety are dependant on a number of factors, including dosage and the user’s personality.

On the other hand, research has been conclusive in showing that CBD possesses anxiety-reducing properties. Once again, experts suggest that a balance of CBD and THC concentrations may be able to maximize the anti-anxiety effects of marijuana.

Research has also shown that the endocannabinoid system plays an important role in regulating depression. Studies have found that enhanced activity of the endocannabinoid system leads to an antidepressant state, suggesting that marijuana may be useful as an antidepressant.

Dopamine: Reinforcement and Reward

The blissfulness and euphoria that is commonly associated with marijuana use can be explained by marijuana’s impact on the reward system of the brain. The reward system mostly consists of dopamine pathways and is directly linked with feelings of pleasure and euphoria as well as drug abuse and addiction.

All substances of abuse are known to cause a release of dopamine and marijuana is no exception. However, studies indicate that marijuana is much less addictive than other common substances of abuse, leading experts to believe that the amount of dopamine release associated with marijuana use may be relatively mild in comparison.

The Risk of Psychosis?

Although the connection between marijuana use and long-term psychosis continues to be debated, research strongly suggests that marijuana use can elicit temporary psychotic-like symptoms. These symptoms are largely attributed to THC and include depersonalization, a prolonged sense of passage of time, transient paranoid ideation and hallucinations.

However, studies show that certain individuals are simply more prone to psychosis, which explains why some users experience more intense psychosis-like effects than others. Furthermore, psychosis-like effects seem to occur in only a small portion of those who use marijuana and may also vary with tolerance and dosage. Interestingly, CBD has been found to have anti-psychotic effects and has even been suggested as an effective treatment of psychotic disorders such as schizophrenia.

What This Means For Your Health

Overwhelming research has shown that marijuana does indeed have an impact on various functions of the brain through its action on the endocannabinoid system. And although psychoactive substances seem to be generally feared by the public, research has demonstrated that marijuana’s ill-effects on the brain are few and far between.

Interestingly, the differences in how first-time and regular users experience marijuana seem to be a result of varying dosage and tolerance factors. Evidence also points to marijuana strains with higher concentrations of CBD as having less psychoactive properties.

Without a doubt, marijuana can have a wide range of effects on the brain and it remains up to the user to weigh the costs and benefits of marijuana use. For some individuals, the potential of addiction or cognitive decline may just be worth the trade-off for reduced levels of anxiety and depression.

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