Psychoactive drugs such as
tobacco,
alcohol, cannabis,
amphetamines, ecstasy,
cocaine, and heroin can change
consciousness, mood, and
thoughts.
Psychoactive drugs are substances that can
alter the consciousness, mood, and thoughts of
those who use them.
Examples include:
tobacco
alcohol
cannabis
amphetamines
ecstasy
cocaine
heroin
Tobacco smoking is spreading rapidly
in developing countries and among
women.
The average consumption of cigarettes
is particularly high in Asia and the Far
East, with the Americas and Eastern
Europe following closely behind.
Prevalence of smoking among adults and youths in selected countries (2008)
Annual per
Prevalence of smoking (%)
capita
Adults
Youths
Country
consumption
Males
Females
Males
Females
of cigarettes
Argentina
1495
46.8
34.4
25.7
30
Bolivia
274
42.7
18.1
31
22
Chile
1202
26
18.3
34
43.4
China
Ghana
Indonesia
Jordan
Kenya
Malawi
Mexico
Nepal
Peru
Poland
Singapore
Sri Lanka
1791
161
1742
1832
200
123
754
619
1849
2061
1230
374
66.9
28.4
59
48
66.8
20
51.2
48
41.5
44
26.9
25.7
4.2
3.5
3.7
10
31.9
9
18.4
29
15.7
25
3.1
1.7
14
16.2
38
27
16
18
27.9
12
22
29
10.5
13.7
7
17.3
5.3
13.4
10
15
16
6
15
20
7.5
5.8
ALCOHOL: Whereas the consumption of alcohol is decreasing in developed
countries, it is increasing in countries of the former Soviet Union and in developing
countries, especially in the Western Pacific Region.
Adult (15+) Per Capita Alcohol Consumption by Development Status
UNDERAGE ALCOHOL USE IN THE UNITED
STATES
• 11 percent of 8th graders reported
drinking during the past 30 days, with
3.6 percent of them drinking to
intoxication.
• 28 percent of 10 graders reporting past
30-day use and 14.5 percent drinking to
intoxication
• 42 percent of 12th graders reporting past 30-day use and 28.1
percent drinking to intoxication.
Source: Johnston, L. D., O’Malley, P. M., Bachman, J. G., & Schulenberg, J. E. (2013). Monitoring the Future national results on
drug use: 2012 overview—Key findings on adolescent drug use. Ann Arbor: Institute for Social Research, The University of
Michigan. From http://www. monitoringthefuture.org//pubs/monographs/mtf-overview2012.pdf (accessed February 22, 2013).
How psychoactive drugs affect the
functioning of the brain
Psychoactive drugs alter communication between
brain cells.
Some psychoactive substances are able to mimic the
effects of neurotransmitters.
Others interfere with normal brain function by
blocking it, or by altering the way neurotransmitters
are stored, released, and removed.
The human brain is organized into a number of
different regions with highly specialized functions.
The hindbrain is vital to staying alive because it controls breathing and
wakefulness.
The midbrain is involved in learning, emotion (limbic system), and reinforcing
behaviors, such as eating and drinking, that lead to pleasure and to life
preservation. This area thus plays an important role in drug dependence.
The forebrain is very complex and its outer layer (the cerebral cortex) controls
the ability for abstract thought and planning. When drug-dependent people
are exposed to stimuli that provoke cravings, specific regions of their
forebrain become activated.
Different psychoactive drugs have different ways of acting in
the brain to produce their effects. They bind to different
receptor types, and can increase or decrease the activity of
neurons through a range of mechanisms.
Consequently, they have different effects on behavior,
different rates of development of tolerance, different
withdrawal symptoms, and different short-term and longterm effects.
The most common psychoactive drugs can roughly be divided
into four groups:
Depressants (e.g., alcohol and sedatives)
Stimulants (e.g., nicotine and ecstasy)
Opioids (e.g., morphine and heroin)
Hallucinogens (e.g., PCP and LSD)
Depressants, such as alcohol, sedatives/hypnotics and volatile solvents,
diminish the activity of the central nervous system.
Substance
Ethanol (alcohol)
Hypnotics and
sedatives
Inhalants (volatile
solvents)
How it works
Tolerance
Withdrawal
Effects of prolonged
use
Alters the effects of Develops due to
Withdrawal from
Changed brain
the neurotransmitters increased processing long-term use can
function and structure,
glutamate and GABA. in the liver and
include shaking,
reduced mental
Probably increases
changes to receptors sweating, weakness, capacity, decreased
activity in the
in the brain.
agitation, headache, brain volume.
dopamine system
nausea, vomiting,
involved in
seizures, and delirium
motivation and
tremens.
learning.
Enhances the effects Develops quickly due Anxiety, alertness,
Memory problems.
of some
to changes in brain restlessness,
neurotransmitters (e.g. receptors.
insomnia, excitability,
GABA).
seizures.
Like other sedatives Some tolerance
Increased
Changes in how
and hypnotics,
develops, but is
susceptibility to
dopamine works in
probably affect
difficult to estimate. seizures during
the body, problems in
specific transmitters.
withdrawal
the nervous system,
Increases activity in
reduced mental
the dopamine system
capacity; psychiatric
involved in
problems.
motivation and
learning.
Stimulants, such as nicotine, cocaine, amphetamines and
ecstasy, increase the activity of the central nervous system.
Substance
How it works
Toleranc
Withdrawal
Nicotine
Activates specific Develops
receptors. Increases through
the production and metabolic
release of dopamine. factors, as well
as receptor
changes.
Cocaine
Prolongs the effects Perhaps short- There is not much
of transmitters such term tolerance. evidence of
as dopamine.
withdrawal.
Depression is
common among
dependent people
who stop using the
drug
Effects of prolonged use
Irritability, hostility, It is difficult to separate
anxiety, unease,
the health effects due to
discomfort,
nicotine from the effects
depressed mood,
due to other components
decreased heart rate, of tobacco.
increased appetite.
Abnormalities in specific
regions of the brain, loss
of some mental capacity,
problems with
movement, decreased
reaction times.
Amphetamines
Increase the release Develops
and prolong the
quickly
effects of dopamine
and related
transmitters.
Fatigue, depression, Sleep disturbances,
anxiety and intense anxiety, decreased
craving for the drug. appetite; changes in
dopamine brain receptors,
changes in metabolism in
some parts of the body,
reduction of mental
capacity and deterioration
of movement.
Ecstasy
Increases the release May develop in Depression and
and prolongs the
some
insomnia
effects of the neuro- individuals.
transmitter serotonin.
Damages some brain
systems, leads to physical
changes and to changes in
behavior.
Long-term psychiatric and
physical problems such as
loss of memory, problems
with decision-making and
self-control, paranoia,
depression and panic
attacks.
RATS ON DRUGS
Opioids, such as morphine and heroin, relieve pain, dull
the senses, and induce sleep.
Substance
Opioids
How it works
Tolerance
Activate specific Due to short-term
receptors that are and long-term
abundant in an area receptor changes,
of the brain that is and to changes in
involved in
the way some cells
motivation and
communicate.
learning.
Withdrawal
Effects of
prolonged use
Can be severe.
Watering eyes,
runny nose,
yawning, sweating,
restlessness, chills,
cramps, muscle
aches.
Long-term changes
in certain receptors.
Changes in learning
and in the response
to stress.
Hallucinogens such as PCP and LSD, can distort
perceptions to induce delusions or hallucinations.
Substance
Cannabis
How it works
Tolerance
Activates specific Develops quickly.
receptors. Affects
the dopamine
system involved in
motivation and
learning.
Hallucinogens (such Different substances Develops quickly.
as LSD and PCP) in this class act on
different brain
receptors.
Withdrawal
Effects of
prolonged use
Withdrawal is rare Long-term exposure
perhaps because
may produce longcannabis remains in lasting reduction of
the body for a long mental capacity.
time.
May make mental
illness worse.
There is no evidence Short or long term
of withdrawal.
disturbed mental
state in which a
person experiences
hallucinations,
delusions,
personality changes
and loss of contact
with reality.
Flashbacks or reexperiencing of drug
effects, long after
drug use.
Inside the Tripper’s Brain