The Brain’s Response to

Methamphetamine

Hi, my name’s Sara Bellum. Welcome to 

my magazine series exploring the brain’s 

response to drugs. In this issue, we’ll 

investigate many fascinating facts about the 

stimulant drug methamphetamine. Some of 

this information was only recently discovered 

by leading scientists.

Speed, meth, chalk, crystal, ice, glass. These 

are all names for the drug methamphetamine. 

Methamphetamine comes in 

many different forms and 

is snorted, swallowed, 

injected, or smoked. 

The smokable form is known as “ice” or 

“crystal,” due to its appearance.

Methamphetamine is a powerful drug. It 

acts by changing how the brain works. It 

also speeds up many functions in the body. 

Methamphetamine has a chemical structure 

that is similar to another drug called 

amphetamine that I explore in my magazine 

on stimulants. Methamphetamine can cause 

lots of harmful things, including inability 

to sleep, paranoia, aggressiveness, and 

hallucinations. I’ll tell you more about 

these later.

The Brain’s Response to

Methamphetamine

What Happens If a Person Uses

Methamphetamine for a Long Time?

The Search Continues

Scientists are using brain imaging techniques, like positron 

emission tomography (called PET for short), to study 

the brains of human methamphetamine users. 

They have discovered that even three years 

after long-time methamphetamine users had 

quit using the drug, their dopamine neurons 

were still damaged. Scientists don’t know 

yet whether this damage is permanent, 

but this research shows that changes in 

the brain from methamphetamine use 

can last a long time. Research with 

animals has shown that the drug 

methamphetamine can also 

damage neurons that contain 

serotonin. This damage also 

continues long after the drug use is 

stopped.

These changes in dopamine and 

serotonin neurons may explain some of 

the effects of methamphetamine. If a person 

uses methamphetamine for a long time, they may 

become paranoid. They may also hear and see things that aren’t there. These are called 

hallucinations. Because methamphetamine causes big increases in blood pressure, 

someone using it for a long time may also have permanent damage to blood vessels in 

the brain. This can lead to strokes caused by bleeding in the brain.

Researchers are only beginning to understand how 

methamphetamine acts in the brain and body. When 

they learn more about how methamphetamine causes its 

effects, they may be able to develop treatments 

that prevent or reverse the damage this drug 

can cause. Maybe someday you’ll make the 

next major breakthrough.

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. 06-4394. Printed 2000. Reprinted 

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
No matter how methamphetamine is 

used, it eventually ends up in the bloodstream where it is circulated throughout 

the brain. Methamphetamine can affect 

lots of brain structures, but the 

ones it affects the most are the 

ones that contain a chemical called dopamine. The 

reason for this is that 

the shape, size, and 

chemical structure 

of methamphetamine and dopamine are similar. 

Before I tell you 

more about dopamine and methamphetamine, I’d 

better tell you how 

nerve cells work.

Your brain is made 

up of billions of nerve 

cells (or neurons). Neurons 

come in all shapes and sizes, 

but most have three important parts: 

a cell body that contains the nucleus and 

directs the activities of the neuron; dendrites, short fibers that receive messages 

from other neurons and relay them to the 

cell body; and an axon, a long single fiber 

that carries messages from the cell body 

to dendrites of other neurons.

Axons of one neuron and the dendrites 

of a neighboring neuron are located very 

close to each other, but they don’t actually 

touch. Therefore, to communicate with 

each other they use chemical messengers 

known as neurotransmitters. When one 

neuron wants to send a message to another 

neuron it releases a neurotransmitter 

from its axon into the small space that 

separates the two neurons. This space is 

called a synapse. The neurotransmitter 

crosses the synapse and attaches to 

specific places on the dendrites of the 

neighboring neuron called receptors. 

Once the neurotransmitter has relayed 

its message, it is either destroyed or taken 

back up into the first neuron where it is 

recycled for use again.

There are many different neurotransmitters, but the one that is most affected 

by methamphetamine is dopamine. Dopamine is sometimes called the pleasure 

neurotransmitter because it helps 

you feel good from things like 

playing soccer, eating a 

big piece of chocolate 

cake, or riding a roller 

coaster. When something pleasurable 

happens, certain 

axons release lots 

of dopamine. The 

dopamine attaches to receptors 

on dendrites of 

neighboring neurons and passes on 

the pleasure message. This process is 

stopped when dopamine is released from the 

receptors and pumped back 

into the neuron that released it 

where it is stored for later use.

How Does Methamphetamine Cause Its Effects?

Because it is similar to dopamine, 

methamphetamine can change the 

function of any neuron that contains 

dopamine. And if this weren’t enough, 

methamphetamine can also affect neurons 

that contain two other neurotransmitters 

called serotonin and norepinephrine. All 

of this means that methamphetamine can 

change how lots of things in the brain 

and the body work. Even small amounts 

of methamphetamine can cause a person 

to be more awake and active, lose their 

appetite, and become irritable and 

aggressive. Methamphetamine also causes 

a person’s blood pressure to increase and 

their heart to beat faster.

Methamphetamine Has Lots of Other Effects

Usually neurons recycle dopamine. 

But methamphetamine is able to fool 

neurons into taking it up just like they 

would dopamine. Once inside a neuron, 

methamphetamine causes that neuron 

to release lots of dopamine. All this 

dopamine causes the person to feel an 

extra sense of pleasure that can last all day.

But eventually these pleasurable effects 

stop. They are followed by unpleasant 

feelings called a “crash” that often lead a 

person to use more of the drug. If a person 

continues to use methamphetamine, they 

will have a difficult time feeling pleasure 

from anything. Imagine no longer enjoying 

your favorite food or an afternoon with 

your friends.

Methamphetamine Changes the Brain

Exploring

the Synapse