“It’s just marijuana!” I can’t tell you how many times I hear this in my work. Many go on to defend using marijuana as safer, less harmful to self and others than drinking alcohol or using other drugs, like cocaine or prescription pain meds.

It’s Just Marijuana or Is It?

Now I am the last person who would try argue which drug (and believe it or not, alcohol is considered a drug) is worse than another. The point of this post is to address those who proclaim, “It’s just marijuana,” as if the consequences of using it aren’t as bad as those of using other drugs. This is not necessarily the case. Why?  Like all drugs, marijuana changes the way the brain works. And it’s those brain changes that can be a problem. To better understand, let me first explain neural networks.

Neural Networks

Neural networks are the brain and body’s communication system, also known as an electro-chemical signaling process. Basically this communication system consists of neurons in the brain, commonly called brain cells, talking to one another and then to and from other neurons throughout the body via the nervous system.  In this manner, the brain controls everything a person thinks, feels, says and does.

This is an illustration of a neural network. Like all drugs, marijuana affects the brain and its normal functioning because of its impact on neural networks – the brain and body’s communication system.

A few basics of a neural network describe in the above illustration, include:

• Brain cells – neurons in the brain – responsible for the “electrical” signals – the message/action.
• Branchlike extensions – carry the outgoing electrical signal (called an axon when it’s outgoing) or the incoming electrical signal (called a dendrite when it’s incoming).
• Synapses – the gap between branchlike extensions.
• Neurotransmitters – the chemical messenger that is triggered at the end of one brain cell’s branchlike extension (axon) that converts the electrical signaling into “something” that can float across the synapse.
• Receptors – located on the receiving branchlike extension (axon) to accept the neurotransmitter. The neurotransmitters lock into these receptors like keys in a door lock. The receptors convert the message/signal back to an electrical signal that shoots up to the incoming branchlike extension on the receiving cell (neuron). That cell decides whether to continue or stop the messaging.

Having all components in a neural network healthy is what helps with the brain and body’s smooth, efficient communication system.

What Drugs Do to Neural Networks

THC chemicals in marijuana change the brain’s communication’s system, as do the chemicals in other drugs, like ethyl alcohol in alcoholic beverages, for example.

Drugs contain chemicals that interrupt or change the brain’s communication system at the neurotransmitter / receptor sites described above. Alcohol’s chemical is ethyl alcohol and marijuana’s chemical is THC, for example.

All drugs reach the brain via the bloodstream. This entry can be through the lungs if smoked, directly into the bloodstream if injected, or through the small intestine, as with alcohol, for example. Once in the brain, the drug chemicals tap into the brain’s neural network communication system and interrupt how neurons normally send, receive and process information.  Take Marijuana for example. Quoting from NIDA’s article, NIDA’s “How Does Marijuana Produce Its Effects,”

THC’s chemical structure is similar to the brain chemical anandamide. Similarity in structure allows the body to recognize THC and to alter normal brain communication.

Endogenous cannabinoids such as anandamide (see figure) function as neurotransmitters because they send chemical messages between nerve cells (neurons) throughout the nervous system. They affect brain areas that influence pleasure, memory, thinking, concentration, movement, coordination, and sensory and time perception. Because of this similarity, THC is able to attach to molecules called cannabinoid receptors on neurons in these brain areas and activate them, disrupting various mental and physical functions and causing the effects described earlier. The neural communication network that uses these cannabinoid neurotransmitters, known as the endocannabinoid system, plays a critical role in the nervous system’s normal functioning, so interfering with it can have profound effects.

For example, THC is able to alter the functioning of the hippocampus (see “Marijuana, Memory, and the Hippocampus“) and orbitofrontal cortex, brain areas that enable a person to form new memories and shift his or her attentional focus. As a result, using marijuana causes impaired thinking and interferes with a person’s ability to learn and perform complicated tasks. THC also disrupts functioning of the cerebellum and basal ganglia, brain areas that regulate balance, posture, coordination, and reaction time. This is the reason people who have used marijuana may not be able to drive safely (see “Does marijuana use affect driving?“) and may have problems playing sports or engaging in other physical activities.
                                                        NIDA’s “How Does Marijuana Produce Its Effects.”

Bottom Line

It doesn’t matter what the drug is – even if it’s just marijuana – there can be an impact on the brain because of the chemical in that drug. At minimum, that impact is the feeling of pleasure a person can get when they drink or use drugs. To find out the specifics of individual drugs, check out NIDA’s Drug Facts.

And check out NIDA’s Drugs, Brains, and Behavior: The Science of Addiction for even more information on the science that explains how drugs – regardless of the kind – change the brain.

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Note: portions of this post appeared in my August 2012 post, “‘It’s Just Marijuana’ – It’s Still a Drug; It Still Affects the Brain.” It has been updated as of August 2020 to reflect current research.

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Lisa Frederiksen

Author | Speaker | Consultant | Founder at BreakingTheCycles.com

Lisa Frederiksen is the author of hundreds of articles and 12 books, including her latest, "10th Anniversary Edition If You Loved Me, You'd Stop! What you really need to know when your loved one drinks too much,” and "Loved One In Treatment? Now What!” She is a national keynote speaker with over 30 years speaking experience, consultant and founder of BreakingTheCycles.com. Lisa has spent the last 19+ years studying and simplifying breakthrough research on the brain, substance use and other mental health disorders, secondhand drinking, toxic stress, trauma/ACEs and related topics.

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