The Brain’s Response to

Stimulants

Hi, my name’s Sara Bellum. Welcome to 

my magazine series exploring the brain’s 

response to drugs. In this issue, we’ll 

investigate the fascinating facts about 

stimulants. Some of this information 

was only recently discovered.

Have you eaten any chocolate or drunk 

any soda lately? If you have, there’s 

a good chance you gave your body a 

dose of a stimulant -- caffeine, which is 

also in coffee.

Eating or drinking a large amount of 

caffeine can make you feel jittery, 

nervous, or energetic. That is because 

caffeine -- like any stimulant -- changes 

the way your brain works.

But caffeine is just a mild example of 

a stimulant. Many other stimulant 

drugs are much stronger -- 

and some are illegal and 

very dangerous. Others 

require a doctor’s 

prescription.

Examples of stronger stimulants 

include:

• Cocaine: Made from the leaf of the 

coca plant, this drug often comes in 

the form of a white powder that some 

people inhale through their nose.

• Crack: A form of cocaine that can be 

smoked.

• Amphetamines: Often called “speed,” 

these pills are sometimes prescribed 

by doctors for medical problems.

• Methamphetamine: A powerful form 

of amphetamine that comes in clear 

crystals (called “ice”) or powder 

(called “crank”) that is smoked or 

injected. 

The Brain’s Response to

Stimulants

Scientists Discover Answers

The Search Continues

Fortunately, scientists have figured out 

how to copy the gene that controls the 

dopamine transporter. This process is 

called “cloning.”

By studying copies of the transporter, 

scientists may learn more about how 

cocaine affects it -- and how to prevent 

those effects. These studies may even lead 

to the discovery of a treatment for cocaine 

addiction.

Scientists are already working to create 

a medication for use as a treatment. This 

chemical would attach to the dopamine 

transporter just like cocaine does, but 

it wouldn’t block dopamine’s normal 

movement back into neurons. By attaching 

to the transporter, the substitute would 

block the effects of cocaine.

There’s still a lot that scientists don’t know about 

the effects of cocaine and amphetamines on the 

brain. Maybe someday you’ll make the next big 

discovery.

Mind Over Matter is produced by the National Institute on Drug Abuse, 

National Institutes of Health, U.S. Department of Health and Human 

Services. These materials are in the public domain and may be reproduced 

without permission. Citation of the source is appreciated. NIH Publication No. 

06-3857. Printed 1997. Reprinted 1998, 2000, 2003, 2005, 2006.

National Institute on Drug Abuse

National Clearinghouse for Alcohol and Drug Information,

P.O. Box 2345, Rockville, MD 20847

1-800-729-6686

For more information, visit:

www.drugabuse.gov
Cocaine and amphetamines change the 

way the brain works by changing the way 

nerve cells communicate. Nerve cells, 

called neurons, send messages to each 

other by releasing special chemicals called 

neurotransmitters. Neurotransmitters are 

able to work by attaching to key sites on 

neurons called receptors.

Miscommunication in the Brain

Although cocaine may make someone feel 

pleasure for a while, later it can damage the 

ability to feel pleasure. Research suggests 

that long-term cocaine use may reduce 

the amount of dopamine or the number of 

dopamine receptors in the brain.

When this happens, nerve cells must 

have cocaine to communicate properly. 

Without the drug, the brain can’t send 

enough dopamine into the receptors to 

create a feeling of pleasure.

If a long-term user of cocaine or crack 

stops taking the drug, the person feels an 

extremely strong craving for it, because 

without it he or she can’t feel nearly as 

much pleasure.

Cocaine Can Damage the Way the Brain Works

Cocaine causes the body’s blood vessels to 

become narrow, constricting the flow of 

blood. This is a problem. It forces the heart 

to work harder to pump blood through 

the body. (If you’ve ever tried squeezing 

into a tight pair of pants, then you know 

how hard it is for the heart to pump blood 

through narrowed blood vessels.)

When the heart works harder, it beats 

faster. It may work so hard that it 

temporarily loses its natural rhythm. This 

is called fibrillation, and it can be very 

dangerous because it stops the flow of 

blood through the body.

Many of cocaine’s effects on the heart are 

actually caused by cocaine’s impact on the 

brain -- the body’s control center.

Cocaine Tightens Blood Vessels

NERVE CELL

nucleus

dendrites

axon

axon terminals

FINALLY

AT THE PERCUSSIONS...

THE HEART

AT THE

KEYBOARD..

THE KIDNEYS

AT THE

TRUMPETS...

THE LUNGS

AT THE

ACOUSTIC

GUITAR...

THE LIVER

One of the neurotransmitters affected by 

cocaine is called dopamine. Dopamine is 

released by neurons in the limbic system -- 

the part of the brain that controls feelings 

of pleasure.

Normally, once dopamine has attached 

to a nerve cell’s receptor and caused a 

change in the cell, it’s pumped back to 

the neuron that released it. But cocaine 

blocks the pump, called the dopamine 

transporter. Dopamine then builds up in 

the gap (synapse) between neurons.

The result: dopamine keeps affecting a 

nerve cell after it should have stopped. 

That’s why someone who uses 

cocaine feels an extra sense of 

pleasure for a short time.