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The Physical Impact of Addiction: The Brain & Nervous System on Drugs

Drugs and alcohol, regardless of their legality, their dosage, or their risks, can have a major impact on the human body. They inhibit the control we have over our bodies, our behaviors, and constantly put us in the face of serious adverse physical consequences—respiratory depression, heart attack, coma, overdose. We often ask ourselves, how can drugs as quiet as marijuana or Adderall have such clout over our health? Where in the body do they go wrong? 

The hard impact of drugs and alcohol begin in their movement about the central nervous system. Upon intake, drugs enter the bloodstream but gain all of their momentum as they travel up to the brain.  Our nervous system consists of the brain (its driving force), the spinal cord, nerve fibers, and specialized nerve cells called neurons that travel up and down throughout the body. These neurons communicate with one another through a series of biological messengers called neurotransmitters, which tell the rest of the body how to feel or react to certain triggers. It is no wonder that the root of addiction lies in the brain. 

If you burn your mouth for example, the body will receive the message of pain. If you are hungry, the body will react to that physical need for food. If you do a bump of cocaine and get high, your brain will deliver a message of pleasure to the rest of your body. Your brain will also tell the rest of your body it wants more. 

Drugs contain chemicals that tap into this communication system, disrupting the way nerve cells send and receive messages, and altering the way the body processes information. There are two specific ways that drugs can affect the central nervous system:

  1. Drugs of abuse often are able to mimic the brain’s natural chemical messengers. Marijuana and heroin, for example, have a very similar cell structure to the brain’s neurotransmitters. This means that these drug chemicals have the ability to mask themselves as natural and fool the brain’s receptors, activating nerve cells to send irregular messages throughout the body. 
  2. Drugs and alcohol also have the power to overstimulate the “reward circuit” in the brain. Methamphetamine and cocaine are examples of this, as both drugs cause the nerve cells in the brain to release abnormally large amounts of natural neurotransmitters, such as dopamine, or act to prevent the signals exchanged between neurons from shutting off.  

Dopamine is a neurotransmitter that aids in our control of movement, emotion, motivation, and pleasure. When a user initiates drug use, the brain releases 2 to 10 times more dopamine than it normally would for natural rewards such as eating or sex. The overwhelming amount of euphoria that a user experiences as a result sets in motion the idea that he will need to use the drug again. Thus begins the addiction cycle: drugs reinforce a pattern that teaches a person to repeat use and re-experience that great sense of pleasure. As the habit of using drugs builds, so does a user’s tolerance, resulting in an inability to enjoy both the effect of drugs and alcohol and what were once other normal life pleasures before drug use had begun.  

Not only does drug abuse alter the way our nervous system releases information, it also alters the neurotransmitters being released to the rest of the body. In addition to producing significant amounts of brain chemicals, drug use can also remove or block their production. Glutamate, for example, is a neurotransmitter that diminishes with long-term drug abuse. Because our bodies require glutamate for learning and memory, our brains will attempt to replace it—leading to even larger cognitive issues. Drug addiction, therefore, often indicates a reduced ability to learn, to pay attention, to make rational decisions, and to control behavior. This can be seen through young adults who abuse marijuana. Smoking marijuana impairs short-term memory and learning, the ability to focus attention, and coordination: Those who start smoking marijuana heavily in their teens lose an average of eight IQ points between ages 13 and 38. 

how does drug use affect your brain


Our nervous system, with the brain at its core, controls how the rest of our body perceives and reacts to sensory stimulants. Drugs, however, travel through this system and interrupt how our body communicates within. By invading our central nervous systems, these psychoactive substances are exactly what inhibits our ability to say “no,” disrupts our ability to make a decision, and promotes the “learning” of a fully inflamed addiction. Drugs then move on to afflict the rest of the body, and anyone, at that point, is at risk of the worst. That is why it is important to stop it as soon as it starts. Young adults facing drug addiction have budding brains, their nervous systems are still developing, and there is still time to make a positive change. 

Call Turnbridge today at 1-877-581-1793 to keep drug addiction out of the mind and body of the person you love most, or read our infographic here for more information on the physical impact of drug addiction.