Drugs and the Brain

The human brain is the most complex organ in the body. We need it in order to drive a car, enjoy a meal, breathe, create a work of art, and enjoy everyday activities. It regulates our basic body functions. It enables us to interpret and respond to everything we experience, and it shapes our thoughts, emotions and behavior. The brain is made up of many parts that work together as a team. Drugs can alter or change important brain areas that are necessary for life-sustaining functions, and can drive the compulsive drug abuse that marks addiction.

The brain stem controls basic functions critical to life, such as heart rate, breathing, and sleeping. The limbic system contains the brain’s reward circuit. It links together a number of brain structures that control and regulate our ability to feel pleasure. Being able to experience pleasure motivates us to repeat behaviors, such as eating and sex, that are critical to our existence. The limbic system is also activated when we take mood-altering drugs. The cerebral cortex contains areas that enable us to see, feel, hear and taste. The front part of the cortex, the forebrain, is our thinking center. It allows us to plan, solve problems, and make decisions. Judgment resides in the forebrain.

The brain is literally a communications center consisting of billions of neurons. Networks of neurons pass messages back and forth to different structures within the brain, the spinal column, and the peripheral nervous system. These nerve networks coordinate and regulate everything we feel, think, and do. Each nerve cell in the brain sends and receives messages in the form of electrical impulses. Once a cell receives and processes a message, it sends it on to other neurons. Neurotransmitters are the brain’s chemical messages. Receptors are the brain’s chemical receivers.

Mood-altering drugs tap in to the brain’s communications system and interfere with the way nerve cells normally send, receive and process information. Some drugs, such as marijuana and heroin, have a chemical structure that mimics natural neurotransmitters. This “fools” the receptors and activates our nerve cells. Although these drugs mimic brain chemistry, they don’t activate nerve cells in the same manner as natural our neurotransmitters. Rather, they lead to abnormal messages being transmitted throughout the brain.

Drugs like amphetamine and cocaine can cause the nerve cells to release abnormally large amounts of natural neurotransmitters, and may prevent the normal recycling of these brain chemicals. This disruption produces a greatly amplified message, ultimately disrupting communication channels. The contrast between natural neurotransmitters and the ones mimicked by mood-altering drugs is like the difference between someone whispering into your ear and someone shouting into a microphone. Abuse of mood-altering drugs targets the brain’s reward system by flooding the circuit with dopamine. Dopamine is a natural neurotransmitter which is present in all regions of the brain. It regulates movement, emotion, cognition, motivation, and feelings of pleasure.

Drugs are more addictive than natural rewards. This is because when these drugs are taken, they release 2 to 10 times the amount of dopamine that natural rewards do. In some cases, this occurs almost immediately (as when the drug is smoked or injected). The effects can last much longer than those produced by natural rewards. The effects these drugs have on the brain’s pleasure circuit dwarfs in comparison to those produced by naturally occurring neurotransmitters. The effect of such a powerful reward strongly motivates people to take drugs again and again.

Just as we turn down the volume on a radio that is too loud, the brain adjusts to overwhelming surges in dopamine and other neurotransmitters by producing less dopamine, or by reducing the number of receptors that can receive and transmit signals. As a result, the impact dopamine has on the reward circuit of a drug abuser’s brain can become abnormally low. When this happens, the ability to experience any pleasure is reduced. This is why the addict eventually feels flat, lifeless and depressed. They are unable to enjoy the things that previously brought them pleasure. They need to take drugs just to bring their dopamine function back to normal. What’s worse, they need to take larger amounts of the drug than they first did to create the dopamine high.

I was aware of the impact drug abuse can have on brain chemistry, but I was in denial as to whether I had reached the level of tolerance. I was surprised to learn that drug abuse can lead to profound changes in our actual circuitry. Long-term health of the brain is also severely compromised. Interestingly, long-term drug abuse can trigger adaptations in habits and non-conscious memory systems, resulting in a type of conditioning known as “triggers.” I found this to be true after long-term abuse of narcotic pain killers. I associated the smells inside a pharmacy with taking oxycodone. My drug and alcohol counselor told me that familiar smells are the source of triggering memory. Even if it’s the smell of Snickerdoodles at Christmastime.

Chronic long-term use of mood-altering drugs can cause disruption in the way critical brain structures interact to control behavior. Continued abuse usually leads to the need for higher amounts of the drug in order to produce the desired effect. This, of course, is what we call addiction. Drug use becomes compulsive. The addict no longer has a choice. Self-control and the ability to make sound decisions are gone. The addict now feels intense impulses to get high.

If someone relapses after starting on a journey to recovery, does that mean treatment has failed? No. The chronic nature of the disease means that relapsing is not only possible, it is likely. The longer the addiction has been continuing, the harder it is to reset the brain’s chemistry. When production of natural neurotransmitters such as dopamine and serotonin is crippled, the addict craves drugs just to feel “normal” again. Relapse merely indicates that treatment needs to be reinstated or adjusted, or that alternative treatment is needed (such as being admitted to a rehab).

If you are struggling with relapse, get in touch with someone from AA or NA. I’ll be praying for you.


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