The Brain

Your brain is the most complex computer ever created. It is responsible for directing your entire life from regulating your moods to coordinating your natural body functions (like breathing and blinking). Our brains perform any number of tasks each and every second with each part of the brain designed to performing specific functions. In essence, the brain is the boss of the body. It runs the show and controls just about everything you do, even when you’re asleep.

The brain is like a big, wrinkly, gray sponge that weighs about three pounds. It’s comprised of many sections, neurons, transmitters, and much more. Drugs and alcohol affect your entire brain, changing it, inhibiting it, stimulating it, and killing it. Many have argued that we only use about 10%-20% of the brain and that they can lose a few brain cells without any problem. If this were true, then why is it that any physical damage to any area of the brain causes some form of impairment?  The fact is that the whole brain is utilized in some way and that there is almost no area of the brain that can be damaged without loss of abilities. Even slight damage to small areas of the brain can have profound effects.

Drugs tend to affect the entire brain, some areas more so than others. Three of the areas in the brain that are greatly affected by drugs are the brain stem, the limbic system, and the cerebral cortex.

The Cerebral Cortex

The cerebral cortex is part of the cerebrum. The cerebrum is the biggest part of the brain, making up about 85% of the brain’s weight. The cerebral cortex is the filling that is spread throughout the brain. The cerebral cortex is responsible for many different senses and it divides these senses into different areas. Each area processes information from our senses, enabling us to see, feel, hear, touch, and taste. The front part of the cortex, the frontal cortex or forebrain, is the thinking center of the brain. It powers our ability to think, plan, solve problems, express emotions, speak, perform movements, and make decisions. The temporal Lobe powers memory, speech, auditory stimuli, perception, and recognition. The parietal lobe deals with orientation, recognition, and stimuli. The occipital lobe deals with visual processing. Many movements associated with the cerebral cortex are voluntary, but some are involuntary.

Brain Stem

Another brain part that is crucial to life is the brain stem. The brain stem sits beneath the cerebrum and in front of the cerebellum. It connects the rest of the brain to the spinal cord, which runs down the neck and back. The brain stem controls involuntary muscles that keep us alive without having to think about it. It performs all of the basic functions your body needs to stay alive, like breathing air, pumping your heart, sleeping, digesting food, and circulating blood. Just think of what would happen if you had to remember to breathe every second of the day, keep your heart pumping blood, remember to blink, and digest your lunch. Now add the millions of other tasks of sending information back and forth to the brain and the body. It’s great that the brain is able to manage all of these tasks without our conscious knowledge!

The Limbic System

The limbic system is located on top of the brainstem and buried under the cortex. It contains the brain’s reward system. The limbic system links together a number of different brain structures. These structures involve many of our emotions and motivations, particularly those that are related to survival. These emotions include but are not limited to fear, anger, and pleasure. These feelings are crucial to motivate us to repeat behaviors. The limbic system is activated when we perform activities that bring us pleasure. However, it can also be activated by drugs.

Drugs can alter important brain areas that are necessary for life-sustaining functions and can drive the compulsive drug abuse that marks addiction. In addition, the limbic system is responsible for our perception of other emotions, both positive and negative, which explains the mood-altering properties of many drugs.

Neurons and Neurotransmitters

The brain is made up of about 100 billion neurons that make up series of nerve cells. Neurons are responsible for controlling all of the bodies “message delivery service” or “send and receive service”. Neurons are able to communicate with each through electrical impulses that travel across the synapses to other neurons. Thousands of neurons can connect to one synapse. When one neuron is activated, it creates a chemical messenger that is called a neurotransmitter. The neurotransmitter is then released into the synapse. These neurotransmitters travel through the synapse and bind to special proteins on the other neurons called receptors.

A neurotransmitter and its receptor are like a lock and key. Only the correct neurotransmitter will fit its correct corresponding receptor for the message to be transmitted. When a neurotransmitter binds to the correct receptor, it can either activate or block the other neurons from sending their own signals. The effect of the neurotransmitter depends on its identity and the type of receptor to which it binds; the same neurotransmitter can have different effects on different neurons depending on the receptors present.

How Drugs Affect the Brain

Drugs are chemicals that change the body and the brain. They alter the brain by tapping into the brain’s communication system and interfering with the way nerve cells normally send, receive, and process information. By changing the brain’s chemistry, the drugs affect neuron signaling in different ways.  By binding with neurotransmitter receptors on neurons, drugs can cause various effects such as a release of high levels of dopamine or serotonin (a.k.a. the brain’s chemicals that make you feel good). This leads many drug users to feel a sense of euphoria when they use their drug of choice, causing them to repeat the behavior until eventually they are able to stop or they become chemically addicted.

Most drugs target the brain’s reward system by tricking the receptors into allowing the drugs to lock onto and activate the nerve cells. This causes the brain to release a large amount of dopamine. However, drugs do not interact with the receptors and neurons in the same way that natural ones would. They lead to abnormal messages being transmitted through the network which causes adverse effects in the brain. For example, cocaine can cause the brain to release an abnormally large amount of natural neurotransmitters or prevent the natural recycling of these brain chemicals. This disruption produces the “high” that the user seeks. It also causes the brain to take action to try and correct the overload that it has received. This is how tolerance develops.

Tolerance and Dependence

The brain is a remarkable computer and it will immediately start to adjust to these new levels of neurotransmitters. Overtime the body will start to reduce the number of receptors for the neurotransmitters. As the body reduces the levels of natural neurotransmitters, more drug chemicals are needed to obtain the desired effect of the drug. This happens because the brain is adjusting its internal chemistry to compensate for the drugs that are in the body. When the user stops taking the drug that the brain has now compensated for, then it is thrown off balance. This is commonly known as withdrawal.

This is your Brain on Drugs

If you use drugs over time, you will most likely become chemically addicted to that drug. This means that more of the drug will need to be used in order to get the same effects. As your tolerance for the drug builds, the more the brain chemistry will change. The drugs are making the brain adjust to the overwhelming surges in dopamine and other neurotransmitters. It adjusts by producing less dopamine or by reducing the number of receptors that can receive signals.

As a result, it affects the user’s reward center in the brain. Low levels of dopamine due to long-term drug abuse affect the ability to experience pleasure. Hobbies that may have once brought pleasure, like playing a sport, now begin to feel flat, lifeless, and dull. Most abusers become depressed because of the depleted chemical levels. This leads the drug user to use the drug more often just to feel and function on a normal level. The user will take even more of the drug just to get the same high. Eventually this abuse leads to profound changes in neurons and brain circuits, with the potential to severely compromise the long-term health of the brain. For example, heroin causes the neurotransmitter Gamma Amino Butyric Acid (GABA) to increase. As the levels of GABA rise it causes the users respiratory system to fail and the users breathing to slow and eventually stop. There are many other neurotransmitters that influence the reward center of the brain, the ability to learn, and natural bodily functions.

For the vast majority of drug users in the world, once isn’t enough. Many users will start to mix different drugs. Most drug overdose related deaths are not caused by just one drug. Mixing drugs can have a catastrophic affect. For example, alcohol is a depressant which slows down the respiratory system depressant. Combining alcohol with another depressant, like heroin, can cause the respiratory system to completely stop, thus causing the user to die.

New drugs enter the market every day and people find new ways to use and abuse them. As the chain of abuse continues, researchers and scientists will be able to more thoroughly study the effects of certain drugs on the brain.


Contributed by Guest Blogger Mark Ambrose-Muzyl