Photo courtesy of NIDA.

When a person first thinks about trying drugs, it is usually a voluntary decision. “Maybe I should see what it’s like... just this once,” you might think. Or a friend dares you. Or you just want to feel good or forget your troubles. Most drugs of abuse - including nicotine, alcohol, marijuana, cocaine, and heroin - activate a part of the brain called the reward system, and that makes you feel good. But just for a little while.
 
Drug abuse has serious consequences. The most serious consequence is that prolonged drug use can change the brain in fundamental and long-lasting ways. Eventually, it becomes difficult to deerive pleasure from other normal activities, such as sports, food, or sex.

After repeated drug use, you reach a point when deciding to use drugs is no longer voluntary. Scientists have proof now that drugs literally change your brain. It’s as if a “switch” goes off in the brain. It is during this transformation process that a drug abuser becomes a drug addict.

Addiction is a chronic relapsing disease characterized by compulsive, often uncontrollable, drug seeking and drug use in the face of negative consequences. Drug addicts need professional help and treatment to help them cope with these changes and possibly change the brain back to normal.

Photo courtesy of the NIDA Web site. From Teaching Packet: The Brain and the Actions of Cocaine, Opiate , and Marijuana.

The brain is made up of a complex network of billions of nerve cells called neurons, as well as other kinds of cells, all protected by the bones of the skull. The typical brain weighs only about 3 pounds, but it is the source of most qualities that make you who you are. Neurons in the brain and spinal cord are part of the nervous system and act as a body’s “Command Central.”
 
The brain is constantly active, even when we are asleep. As a matter of fact, asleep or awake, the brain requires 20 percent of the heart’s output of fresh blood and 20 percent of the blood’s oxygen and glucose to keep functioning properly. Glucose is a type of sugar that is our brain’s primary fuel.
 
The brain produces enough electrical energy to power a 40-watt light bulb for 24 hours. That’s a lot of energy for a human organ a little bigger than a softball.
 

Illustration used with permission, courtesy of Lydia V. Kibiuk and the Society for Neuroscience.

Neurons are unique because they can send information from the brain to the rest of the body. Your brain communicates with the rest of your body by sending messages from one neuron to the next and ultimately to the muscles and organs of the body. Neurons can also store information as memories.
 
Typically, a neuron contains three important parts: a cell body that directs all activities of the neuron; dendrites (the part that looks like tree branches), which are short fibers that receive messages from other neurons and relay those messages to the cell body; and the axon, a long single fiber that transmits messages from the cell body to dendrites of other neurons. Every moment, messages are moving with amazing speed back and forth from neuron to neuron. As a matter of fact, scientists often compare the activity of neurons to the way electricity works.
 
A neuron communicates with other neurons at special places called synapses or synaptic clefts. To send a message, a neuron releases a chemical messenger, or neurotransmitter, into the synaptic cleft. From there, the neurotransmitter crosses the synapse and attaches to key sites called receptors on the next neuron in line. When neurotransmitters attach to these receptors, they cause changes inside the receiving neuron and the message is delivered.
 
Neurons communicate with each other through a network of interconnected cells that scientists are still trying to fully understand. Scientists do know that this complex communication system within the brain can be disrupted by the chemicals in drugs. Did you know that more than 400 chemicals are in a marijuana leaf? And over 4,000 chemicals besides nicotine are in tobacco!
 

Photo courtesy of the NIDA Web site. From Teaching Packet: The Brain and the Actions of Cocaine, Opiates, and Marijuana.

4: The brain is your body’s “Command Central.”

Your brain controls more than the way you think. The brain controls our physical sensations and body movements. How we understand what we see, hear, smell, taste, and touch. Our sense of balance and coordination. Memory. Feelings of pleasure and reward. The ability to make judgments. When we catch a football, dance, jog, speak, sing, laugh, whistle, smile, cry - that’s our brain receiving, processing, and sending out messages to different parts of our body.

When we feel good for whatever reason - laughing with a friend or seeing a good movie or eating our favorite ice cream - the brain’s reward system is activated. As we said before, the reward system is the part of the brain that makes you feel good. The reward system is a collection of neurons that release dopamine, a neurotransmitter. When dopamine is released by these neurons, a person feels pleasure.

Scientists have linked dopamine to most drugs of abuse - including cocaine, marijuana, heroin, alcohol, and nicotine. These drugs all activate the reward system and cause neurons to release large amounts of dopamine. Over time, drugs damage this part of the brain. As a result of this damage, things that used to make you feel good - like eating ice cream, skateboarding, or getting a hug - no longer feel as good.