Hallucinogens are drugs which cause altered states of perception and feeling and which can produce
flashbacks. They include natural substances, such as mescaline and psilocybin that come from plants
(cactus and mushrooms), and chemically manufactured ones, such as LSD and MDMA (ecstasy).
LSD is manufactured from lysergic acid, which is found in ergot, a fungus that grows on rye and other
grains. MDMA is a synthetic mind-altering drug with hallucinogenic properties. Although not a true
hallucinogen in the pharmacological sense, PCP causes many of the same effects as hallucinogens and
so is often included with this group of drugs. Hallucinogens have powerful mind-altering effects. They
can change how the brain perceives time, everyday reality, and the surrounding environment. They
affect regions and structures in the brain that are responsible for coordination, thought processes,
hearing, and sight. They can cause people who use them to hear voices, see images, and feel sensations
that do not exist. Researchers are not certain that brain chemistry permanently changes from
hallucinogen use, but some people who use them appear to develop chronic mental disorders. PCP and
MDMA are both addicting; whereas LSD, psilocybin, and mescaline are not. 

Research has provided many clues about how hallucinogens act in the brain to cause their powerful
effects. However, because there are different types of hallucinogens and their effects are so
widespread, there is still much that is unknown. The following paragraphs describe some of what is
known about this diverse group of drugs. 

Mechanism of Action 
 

LSD binds to and activates a specific receptor for the neurotransmitter serotonin. Normally, serotonin
binds to and activates its receptors and then is taken back up into the neuron that released it. In
contrast, LSD binds very tightly to the serotonin receptor, causing a greater than normal activation of
the receptor. Because serotonin has a role in many of the brain's functions, activation of its receptors
by LSD produces widespread effects, including rapid emotional swings, and altered perceptions, and if
taken in a large enough dose, delusions and visual hallucinations. 

MDMA, which is similar in structure to methamphetamine, causes serotonin to be released from
neurons in greater amounts than normal. Once released, this serotonin can excessively activate
serotonin receptors. Scientists have also shown that MDMA causes excess dopamine to be released
from dopamine-containing neurons. Particularly alarming is research in animals that has demonstrated
that MDMA can damage and destroy serotonin containing neurons. MDMA can cause hallucinations,
confusion, depression, sleep problems, drug craving, severe anxiety, and paranoia. 

PCP, which is not a true hallucinogen, can affect many neurotransmitter systems. It interferes with the
functioning of the neurotransmitter glutamate, which is found in neurons throughout the brain. Like
many other drugs, it also causes dopamine to be released from neurons into the synapse. At low to
moderate doses, PCP causes altered perception of body image, but rarely produces visual
hallucinations. PCP can also cause effects that mimic the primary symptoms of schizophrenia, such as
delusions and mental turmoil. People who use PCP for long periods of time have memory loss and
speech difficulties. 

The following activities, when used along with the magazine on hallucinogens, will help explain to
students how these substances change the brain and the body.