||Drugs and the Body: How Drugs Work
People have had drugs and alcohol
on their minds for as long as drugs and alcohol have been around
-- which is just about as long as people have been people.
It's one of the oldest pastimes
on the planet, altering our thoughts and feelings and moods with
whatever psychoactive substance is around -- and seems like a
good idea at the time.
It's also one of the most unpredictable
pastimes on the planet, for the simple reason that drugs and
alcohol produce their effects by temporarily tilting the biochemical
balance inside our bodies and brains.
Until recently, not much was
really known about how, exactly, drugs and alcohol did their
"tilting." But that's starting to change.
Why? A main reason has been the
explosion of drug-related scientific research that's taken place
over the past two decades. It's caused a shift as radical, in
its own way, as the drug revolution of the 1960's and '70s that
It's altered, in a fundamental
way, our understanding of how psychoactive chemicals affect our
bodies and brains and, indeed, how our bodies and brains work
together to generate our perceptions and experience of our lives.
That's why we've put together
In it, we'll examine the latest
findings on how psychoactive chemicals are processed in the body.
We'll focus on drug-related changes in body chemistry and examine
how those changes alter mood and mental processes.
And we'll review the short- and
long-term health consequences of specific drug effects.
Because the simple fact is that
we've probably discovered more about the precise ways in which
drugs affect the body in the past 10 years than in the 10,000
years before that.
And what we've learned puts a
whole new spin on our understanding of how drugs work and why
human beings have always been attracted to chemicals that change
the way we think and feel.
Scientific revolutions often
hinge on a single discovery or observation which, when viewed
from inside a prevailing paradigm, cast so much doubt on its
assumptions that earlier beliefs are simply swept away.
Often, such discoveries meet
with resistance -- especially when they run counter to accepted
beliefs and religious orthodoxy, as was the case of Galileo's
observation that the earth revolves around the sun.
Other times, a discovery fits
so neatly into the evolving body of knowledge surrounding a discipline
that it's accepted almost instantly as an obvious confirmation
of what leading researchers have long suspected to be true.
The current revolution in our
understanding of drugs and the body began in 1975, with the latter
type of discovery.
It started in 1975 in the laboratories
of two addiction researchers in Scotland, Hans Kosterlitz and
John Hughes, who discovered simple amino-acid chains in a centrifuged
extract taken from pigs' brains which, when applied to vas deferens
tissues from mice, could block electrically-stimulated convulsions
in the tissue -- just like morphine.
The discovery confirmed what
had been proposed by earlier researchers, that the brain manufactures
its own "drugs" -- chemicals that relieve pain and
control stress and trigger arousal and the countless other biological
reactions that shape the precise ways that we think, act, and
They also discovered a system
of specialized receptors in the brain, central nervous system,
and other body systems that interact with these chemicals --
and with drugs and alcohol.
Pinpointing receptors as the
site of drug action is the psychopharmacological equivalent of
finding out the world isn't flat. It's reshaped our old ideas
about what causes drug addiction and redefined notions about
how to treat it.
It may even offer answers to
long-standing questions about the origins of mental illness and
behavioral problems -- from anxiety to anorexia nervosa. And
it lies at the heart of understanding the full range and complexity
of drug actions and effects.
But before we can talk about
specifics, we need to briefly review the basics of how all drugs
work in the body.
Because how quickly and well
drugs "turn on" brain receptors depends on a number
of factors that come into play before they arrive at their receptor
And even though the ins and outs
of drug processing are complicated, they're easily boiled down
to four basic steps:
- Administration...or how drugs enter the body;
- Distribution...or how drugs move to the brain and other
- Action...specific ways in which drugs produce
their effects; and
- Removal...how the body stops drug actions and eliminates
In this chapter, we'll look at
the first of these factors, administration.
It's an important place to start.
Because sometimes, simple differences in how a chemical gets
into the body can make a big difference in the range of effects
it eventually produces.
People have spent almost as much
time thinking up ways to get drugs into the body as understanding
what they do once they get there.
That's because a drug's effects
are determined in large part by the way it's administered. A
simple rule of thumb is that the quicker a chemical enters the
bloodstream, the more intense its effects.
There are four main ways a drug
can be administered: orally, or through injection, inhalation,
or direct absorption through body tissues. Each carries its own
biological costs and consequences.
Oral: Taking drugs orally is simple: All you have to
do is swallow. But it's also the slowest way of producing effects
since pills or capsules have to pass through more body systems
before reaching the brain.
Food and digestive enzymes also
slow drug movement, and can weaken or block a chemical. That's
why heroin is almost never taken orally; it loses almost 90 percent
of its psychoactive punch in the stomach and liver, so that most
of a dose is wasted.
Injection: The fastest way of getting a drug to
the brain is by injecting it directly into the bloodstream. Intravenous
injection ("mainlining") triggers effects almost before
a user can pull out the needle.
Chemicals can also be injected
under the skin ("skin-popping") or shot into deep muscles
(intramuscular injection). Since drugs must move through more
layers of body tissue with these methods, onset of effects is
delayed by about 15-30 minutes.
Inhalation: Drugs that are smoked or inhaled move
across air sacs in the lungs before being absorbed into the bloodstream.
How quickly they reach the brain
depends on the size of the individual drug molecule. Volatile
gases, like ether, produce effects almost immediately, while
marijuana and other drugs that are inhaled as particles in smoke
go to work less quickly.
Direct Absorption: Drugs can also be absorbed directly
across body tissue. Examples include cocaine (which, when sniffed,
is absorbed through nasal membranes) and smokeless tobacco, in
which nicotine is absorbed through cells lining the cheek and
Since all routes of drug administration
allow foreign substances to pass directly into the body, side
effects are unavoidable. Problems can range from simple nausea
to nervous system damage and lung cancer.
Other risks are tied to other
factors, such as injection-linked infections, abscesses, and
tissue damage. IV drug users also face sharply higher risks for
contracting and spreading the HIV virus that causes AIDS by sharing
contaminated needles and syringes.
Still, despite their differences,
all routes of administration have one thing in common: They get
drugs inside the body and on their way to the brain.
But before psychoactive chemicals
can do any psycho-activating at all, they must first hook up
with an internal body transport system to carry them to the brain.
But that's another story -- or,
at least, another chapter.
Once a drug gets inside the body,
lots of things start happening all at once. For starters, as
the chemical moves into the bloodstream, it circulates to body
organs and tissues.
Then, after linking up with receptor
cells in the brain and other body sites, it eventually migrates
to the liver, which breaks it down and flushes it away.
Sound simple enough? Maybe --
from a distance. But up close, things get a little more complicated.
That's why we're now going to
look at the processes the body goes through after a chemical
is administered, but before it triggers its main psychoactive
In the section that follows,
we hope to get you close enough to the action to give you an
idea of the complexity of drug actions and effects, while keeping
enough distance from the process that things keep sounding simple.
In the body, drugs are absorbed
into cells and tissues the way water soaks across a sponge. They
spread from areas of high concentration to low concentration,
passing through millions of cell membranes along the way.
If all drugs were absorbed at
the same rate, their effects would begin at about the same time.
But they aren't and they don't. That's because drug molecules
differ in solubility, or how they dissolve in body tissue.
Everyone who's ever spent time
at a salad bar knows that oil and water don't mix. That's why
the oil in Italian dressing always eventually rises to the top,
no matter how long you stir -- or how hard you shake it.
Drug molecules work in much the
same way. Some mix more easily with oil (body fats), others with
water. And since most cell membranes contain high levels of fats,
drugs that mix with fat can penetrate them quickly. Larger water-soluble
drugs have a harder time of it, though. They can bead on the
cell surface, or pass slowly through tiny pores in the membrane.
Fat solubility plays a key role
in how quickly a drug reaches the bloodstream -- and how soon
after it gets to the brain. All mood-altering drugs dissolve
in fat -- some just do it faster than others.
Drugs are carried to their sites
of action through the bloodstream.
The process is a fast one: The
heart recycles the total blood supply in about a minute, pumping
drug molecules to all parts of the body.
The brain gets the largest share
of that supply -- about 16 percent of all circulating blood.
That means that all drugs (and other substances found in blood)
are carried to the brain. But not all can enter it.
That's because the brain is surrounded
by a wall of veins and capillaries, known as the blood-brain
barrier, which protects brain tissues from impurities that are
carried in blood. It's practically leakproof: Unlike most other
cells, it has no pores. Only oxygen, food, and fat-soluble chemicals
can filter across.
All psychoactive drugs pass the
barrier, or they wouldn't be psychoactive. Other drugs -- penicillin,
for example -- can't and don't.
Once drug molecules make it across
the blood-brain barrier, they move to receptor sites throughout
How long they stay there -- and
how long they keep on producing effects -- depends on how quickly
the drug is broken down and removed in a process called metabolism.
Drugs are removed from the body
just like milk, pizza, hot dogs, and Mom's apple pie. The liver
breaks big molecules into simpler parts that can be mixed with
water and flushed away. It's a simple input-output process.
But in other ways, drug molecules
aren't like apple pie, at all -- at least not any apple pie we've
ever heard of.
For one thing, they're more complex
-- and harder to break down.
Some drugs are so complex that
they have to pass through the liver several times before they're
eliminated from the body. That's why peak drug effects can last
a long time; they begin to fade only when a chemical is broken
down faster than it's absorbed.
The process of breaking drugs
down is called drug metabolism. Breakdown products are known
Metabolism mostly takes place
in the liver, where enzymes snap drug molecules apart like tinker
toys. Metabolism also occurs in the kidneys, gut, lungs, and
blood, but on a smaller scale.
Drug metabolism is easily the
most detailed step in drug processing, since a single drug can
produce dozens of metabolites, some of which may also trigger
THC, the main mind-altering chemical
in marijuana, has at least 25 metabolites, and it can take up
to five days before all of them leave the body -- even longer
in the case of heavy smokers.
Alcohol is a much simpler chemical
that's broken down and removed quickly -- usually in less than
High-fat areas of the body, such
as the brain, are lightning rods for THC and other fat-soluble
drugs. These chemicals are stored in fatty organs and cells,
and only slowly inch back into the bloodstream for removal.
This buildup explains why certain
highly fat-soluble drugs -- like barbiturates, tranquilizers,
marijuana, and others -- may produce lingering effects hours
or days after use.
Drugs that are more water-soluble
Heroin is a good example. It
isn't stored in the body. In fact, it's broken down so quickly
that users must readminister the drug every 4-5 hours to maintain
Drug highs fade as chemicals
are converted into simpler particles by the liver. From there,
the action switches to the kidneys, which remove metabolites
and any wastes in the bloodstream, and pass everything on to
Drugs are also removed in the
large intestine and in sweat, saliva, and milk from breast-feeding
mothers. Since some alcohol is removed in the process of breathing,
Breathalyzer tests are able to directly measure blood alcohol
levels -- and intoxication.
As we have seen, each step in
the biological transformation of drug processing is a story all
its own, involving countless chemical actions and reactions that
we can't begin to cover in detail here.
What we have tried to do is outline
the basic points and processes of drug movement through the body.
And there's a good reason for
Because even though drugs and
alcohol only produce their psychoactive effects in the brain,
those effects are shaped by other processes in other parts of
And, as we'll soon discover,
the changes that drugs and alcohol trigger there are no less
important than their effects on the brain.
We've known for a long time that
drugs and alcohol change the way we think and feel. But until
just a few years ago, we didn't get very specific about it.
We just sort of supposed that
they changed something in the body to create those effects.
But in 1975, when researchers stumbled across receptors in the
brain that trigger drug effects, we began to learn just what
that something was.
And things have never been the
We now know that drugs and alcohol
produce their effects by altering normal chemical processes in
the brain. We also have a better understanding of how and where
those changes happen.
And that understanding has unleashed
an avalanche of new research into how the brain works and what
goes wrong when it doesn't.
That's what this chapter is all
about. We won't even attempt to trace all the twists and turns
of brain chemistry. That's as difficult (and as time-consuming)
as counting grains of sand on a beach or freckles on a redhead.
What we will do, though, is review
the basics of how the brain works and examine how drugs and alcohol
affect those processes.
Because psychoactive chemicals
do alter the way our brains work.
The degree of change depends
on the drug, its potency, and how it's processed by the body.
But the type of change is a function of how a drug reacts at
specific sites of action in the brain.
Once a chemical passes through
the blood-brain barrier, it begins to encounter neurons, the
nerve cells that form the communications pathways of the brain
and nervous system.
Nerve cells monitor changes in
the body and send information about those changes to other nerve
cells and to response centers in the brain. It's this constant
flow of electrochemical impulses that determines how we think,
act, and feel from moment to moment.
Drugs and alcohol are an abnormal
source of change in this system. They alter normal operations
and change the flow of normal cell-to-cell communications.
And they do that by interacting
with a specialized part of the nerve cell membrane called the
Neurons communicate by sending
and receiving electrochemical messages.
These signals travel as a wave
of electrical current down the cell body of the neuron and as
chemical transmitters (called neurotransmitters) that are fired
across the synapse, or the gap separating one neuron from another.
Receptors in adjacent nerve cells
are activated by the transmitter, which generates a fresh electrical
signal that triggers a new burst of neurotransmitters to neighboring
neurons. The whole process happens in a flash, and sets off thousands
or millions of similar reactions along the way.
Receptor sites are highly specialized.
They respond only to particular sets of messages carried by specific
types of neurotransmitters.
It's these chemical messengers,
tiny pellets of neurotransmitter that jump the synapse, that
form the basis of everything we think and feel.
We could easily spend the rest
of this booklet discussing neurotransmitters. Because increasingly,
research is showing that they're more than simple messengers.
In a real way, they are the message
-- of consciousness itself -- conveyed through a built-in system
of stress-reducers and pain-relievers that acts as the body's
own medicine cabinet.
Where do drugs and alcohol fit in?
They change the way neurotransmitters
interact with receptors.
How? In lots of ways.
For starters, drug molecules
plug into brain receptors like keys slipping into locks. There,
they can turn up or turn down a neural signal -- or even turn
a signal on or off altogether. Then again, they can change a
cell's receptivity to other signals.
The exact change seems to depend
on the drug.
Alcohol, for example, alters
the sensitivity of the entire cell membrane, while heroin occupies
receptor sites involved in the body's own internal pain-relief
system. Pain is still felt, but the drug blocks the cell's response
Other drugs work in similar ways
-- which might not be all that bad, if that's all that drugs
The problem is that it isn't.
So why do people choose to voluntarily
rewire their own neurocircuitry with drugs and alcohol? There
are a lot of different reasons, and you know most of them already.
Either they feel anxious or insecure
or they can't sleep or eat or else they eat or sleep too much.
In fact, there are almost as many reasons for taking drugs as
there are people who take them.
But the main reason that drugs
and alcohol have held their fascination for quite so long is
that psychoactive chemicals cause physical and emotional changes
that people see as desirable, in one way or another.
On an objective level, main effects
center on actions taking place at receptors in the brain and
central nervous system. Side effects can involve actions at other
sites in the body.
But on a subjective level, effects
are experienced in the mind, either as a pleasurable way to pass
time or as an indispensable aid to happiness and well-being.
In addition to the factors we've
talked about thus far, the total range of a drug's effects are
shaped by other elements, including drug purity, potency, and
toxicity, and by the way those factors "fit" personality
traits of the user.
And that brings us to what we'll
look into next -- the short-term effects of specific drugs and
alcohol. Because psychoactive chemicals can trigger a world of
change. Otherwise, no one would be interested.
And almost everyone seems to
be, in one way or another.
Let's start with alcohol. Everyone
else does, often enough.
Alcohol can take a number of
forms -- beer, wine, or liquor.
We'll lump all the types together,
though, because from a pharmacological standpoint, each is just
a medium for ethanol, the psychoactive ingredient in all alcoholic
In the body, alcohol is mostly
absorbed from the stomach and intestines and quickly moves into
the bloodstream. Unlike other drugs, alcohol dissolves in both
water and fat, and it's distributed evenly throughout the body.
Since it's broken down in the
liver at a steady rate of about a third of an ounce of pure ethanol
per hour (the approximate amount of alcohol found in an ounce
of 80-proof whiskey or a single beer or glass of wine), most
people can consume a drink or so in an hour with few effects.
Greater consumption causes a backlog of alcohol in the body that
eventually results in intoxication. Drinking much more very quickly
can cause overdose, even death.
In the brain, alcohol produces
general depression by lowering the sensitivity of brain cells.
Low-dose effects include feelings
of relaxation and disinhibition, related to slowed activity in
the brain's behavioral control centers.
Alcohol also slows breathing
centers in the brain, and can impair memory, judgment, and coordination.
Alcohol's effects are much like
the effects of other central nervous system depressants, including
barbiturates (Seconal®, Nembutal®) and non-barbiturate
sedative-hypnotics (Placidyl®, Doriden®) and the "minor"
tranquilizers (Valium®, Librium®, and Tranxene®).
Depressants are absorbed at varying
rates in the stomach and intestines. The onset of action varies
by drug, but all are broken down slowly so that effects can linger
hours or days after use.
Depressants cut the intensity of nerve signals to higher brain
centers. Like alcohol, they trigger general CNS depression, relieving
anxiety and, ultimately, inducing sleep. Barbiturates and other
sedative-hypnotics can suppress breathing: Overdose deaths can
occur at doses as little as three times the therapeutic dose.
The exact mechanism by which
depressants exert their effects is vaguely understood, although
the drugs are thought to boost activity of the anti-anxiety transmitter
gamma-aminobutyric acid (GABA), which inhibits the neuronal firing
of excitatory impulses.
A number of hallucinogenic drugs
are widely used today, including LSD, mescaline (peyote), psilocybin
("magic mushrooms"), PCP or phencyclidine ("angel
dust"), ketamine ("Special K"), and MDA and MDMA
Most are absorbed quickly and
spread to all parts of the body, producing effects within an
The full range of actions triggered by hallucinogenic drugs is
still unknown, but the drugs seem to overload thought, perception,
and arousal centers by altering activity in various brain structures
through their direct action on neurotransmitter systems.
LSD is believed to alter the
release and biological activity of the neurotransmitter serotonin,
and other neurotransmitters, including dopamine and norepinephrine.
Very little LSD ever reaches the brain, but due to its extreme
potency, psychoactive effects set in at brain levels of just
a few millionths of a gram.
The amphetamine-based drugs,
MDA and MDMA, act on norepinephrine receptors which often figure
into the body's fight-or-flight system, triggering agitation
Phencyclidine and ketamine produce
their dissociative anesthetic and hallucinatory effects by acting
directly on a specialized system of postsynaptic receptors for
the excitatory neurotransmitter glutamate.
There are several basic types
of inhalants: solvents (glue, typewriter correction fluid, gasoline),
aerosols (spray paint and cooking spray), amyl and butyl nitrite
(and newer, act-alike variations, including cyclohexyl nitrite),
and nitrous oxide.
After inhalation, drug molecules
rush immediately to the brain, triggering sudden, fast-fading
effects. Amyl and butyl nitrite produce sudden dilation of veins
to the heart. Nitrous oxide is one of the few drugs which exit
the body unchanged in breath.
Most inhalants act as depressants
with mild hallucinogenic properties by slowing nerve signals
and suppressing arousal centers in the brain.
Amyl and butyl nitrite relax
smooth muscles and blood vessels, producing rapid heartbeat and
a fast drop in blood pressure. Although their exact mode of action
is still unknown, their main effects may result from reduced
blood flow to the inner brain.
Drug molecules in marijuana move
quickly from the lungs to the bloodstream and are absorbed within
Because pot isn't a single chemical
(It's composed of some 420 different chemicals, 62 of which --
known as cannabinoids -- occur nowhere else in nature), metabolism
is slow and involves dozens of by-products that are stored in
fatty tissues, including the brain. Traces of pot's main psychoactive
ingredient, tetrahydrocannabinol (THC), and other metabolites
can be detected in urine for 5 days after smoking, for weeks
in heavy users.
THC easily passes through the
brain barrier, producing both selective stimulation and depression
of thought, memory, and perceptions.
The exact mechanism by which
marijuana triggers its effects still isn't altogether clear,
although we have recently learned that the drug interacts with
a distinct set of cannabinoid receptors, known as anandamides.
Narcotics fall into two classes,
opiates (heroin, morphine, and codeine), and synthetics (Demerol®,
Percodan®, Talwin®, and Darvon®).
Opiates are poorly absorbed in
the stomach, but produce almost immediate effects when injected
or inhaled. Drug effects usually peak within an hour. The drugs
are broken down quickly in the liver, and are rapidly eliminated
from the body.
In the brain, narcotics relieve
pain and increase sleepiness by replacing internal pain relievers
(called endorphins) at their receptor sites.
Heroin and morphine also depress
brain centers for breathing and heart rate. The drugs can also
cause nausea, vomiting, and itching.
Stimulants rank alongside alcohol
at the top of the humanity's list of all-time pharmacological
Examples include cocaine (including
freebase and "crack"), amphetamines (Dexedrine®,
Benzedrine®), methamphetamine ("crystal," "crank"),
nicotine, and caffeine.
In the body, amphetamine effects
generally start within an hour when swallowed, almost instantly
when injected, and can last 6-8 hours or longer. Cocaine acts
for a briefer period (less than an hour), since the drug is metabolized
within 15 minutes. Freebase or "crack" is the fastest-acting
and shortest in duration: It speeds to the brain within seconds,
and fades in minutes.
In the brain, stimulants increase
the supply and action of neurotransmitters involved in arousal
(particularly norepinephrine and dopamine), producing a sharp
rise in energy levels and sharp drops in appetite and fatigue.
The drugs also act directly on
heart muscles, triggering irregular heartbeat. Caffeine and nicotine
produce a more general brain cell stimulation, while nicotine
acts on receptors for acetylcholine. High blood levels of stimulants
can trigger psychotic states.
By now, you might have guessed
that since drugs so powerfully alter the way the brain works,
chemicals eventually create lasting changes.
And if you did, you'd be right.
Drugs and alcohol can trigger
long-lasting side effects. Some are reversible, fading away in
the months and years after drug use is stopped.
Others, particularly tissue damage
caused by constant exposure to chemicals, don't go away quite
In this section we'll discuss
some of the more common drug-induced changes, including tolerance,
physical and psychological dependence, and health hazards linked
to long-term drug use.
They're worth serious attention.
Because when it comes to drug abuse, sometimes even when you
think you're getting away with it, you're still not getting away
If you lived next to railroad
tracks, sooner or later you'd stop waking up at night when the
2 a.m. coal train rumbled by.
It's a process of gradual habituation,
and it's a good thing. In fact, if we couldn't filter out irrelevant
sights and sounds and other stimuli of everyday life, we'd have
a hard time ever making sense of anything, buried in an avalanche
Drug tolerance works in much
the same way. When nerve cells are exposed to regular doses of
a chemical, they gradually adjust to it being around. That's
why, over time, repeated doses of a drug tend to produce less
Nerve cells may develop tolerance
by creating "filters" for drug effects, just as we
become able to block out distracting sounds. Researchers think
such filters may involve physical changes to nerve cells that
allow them to operate "normally," even when the drug
Degree and rate of tolerance
varies with the drug. LSD produces a short-term form of tolerance
in just a few days, while marijuana and alcohol require months
of regular use.
Not only that, but the body may
only become tolerant to certain drug effects -- to the sleep-inducing
properties of barbiturates, for example, but not to the drugs'
respiratory-depressant effects. Or it may become tolerant to
other drugs in the same class (as is the case with depressant
drug "cross-tolerance"), whether or not it's been exposed
to specific drugs in the family before.
But no matter what specific form
tolerance takes, it means that users must take larger doses of
a drug to achieve desired effects. And that can lead to dependence.
And that can lead to trouble.
People have suffered problems
of drug dependence for centuries. But the process is still poorly
Simply stated, a person who is
chemically-dependent needs regular doses of the chemical in order
to function normally. When the chemical is removed, the person
experiences a syndrome known as withdrawal.
The withdrawal syndrome can continue
long after the drug has left the body. It can include largely
physical symptoms, such as nausea, fever, and chills, or psychological
problems, including anxiety, irritability, and insomnia.
What causes things to go so awry?
Since the discovery of drug receptors,
researchers increasingly view dependence as an imbalance of brain
chemistry. They suspect that the brain and central nervous system
adapt to some drugs by changing the "rules" by which
transmitters are made and fired.
Other chemicals, such as alcohol,
seem to produce structural changes in nerve cells themselves.
That's why an increasing part of addiction research has begun
to focus on ways for helping the brain recover its own chemical
balance, through diet, exercise, meditation, or other therapies
(such as the use of antidepressant drugs) designed to bring brain
chemistry back into balance.
It can be a tricky proposition.
And for some, it's easier said than done.
Long-Term Health Effects
Continuous drug use produces
lasting changes in the body. The range of possible effects and
side effects on organs and body systems is immense -- so vast,
in fact, that we're not even going to try to cover them all here.
Still, we will point out that
most long-range biological effects seem directly linked to where
a chemical spends its time -- how it's processed and where it
acts in the body.
It shouldn't be surprising that
tobacco damages the lungs and heart and is linked to cancers
of the mouth, throat, and lungs. That's the route nicotine and
all the other chemicals in tobacco take in entering the body.
Alcohol provides another clear
In addition to its action on
brain cells, alcohol speeds up formation of fats in the liver.
In heavy, long-term drinkers, these fatty deposits lead to cirrhosis,
a scarring of liver tissues that eventually stops the liver from
And a similar fat buildup in
arteries leading to the heart is now tied to heart disease and
hardening of the arteries.
Heroin, for all its sinister
reputation, seems to produce little direct tissue damage. Because
of its solubility, it's absorbed and removed quickly.
In fact, heroin's main side effect
(aside from physical dependence) is chronic constipation. That's
because it engages receptors in the digestive system as well
as the brain, slowing movement of food through the stomach and
Drugs of all types also produce
a range of indirect health effects.
Some -- particularly alcohol
and depressants -- reduce overall vitality by interfering with
the natural sleep process. Others -- including marijuana and
amyl and butyl nitrite -- may impair immune response.
There's a point and a problem
in all of this.
The point is that drugs and alcohol
can powerfully alter the way our bodies work -- sometimes even
years after we stop taking them.
The problem is that we may not
notice all -- or even most -- of these changes until long after
And by then, the damage is often
We've come a long way in piecing
together how drugs and alcohol work in the body. We've learned
how they're absorbed into body tissue and how they're removed.
We've reviewed sites in the body
where drugs link up with internal systems to produce their effects.
And we've traced those actions to changes in body chemistry and
their corresponding effects on health and behavior.
We've covered a lot of ground
in a very little time, as impartially as we could.
But in spite of our own best
efforts (and the best efforts of human beings for the past few
thousand years) we still haven't found a drug that's harmless,
Simply because there doesn't
seem to be any.
That's because all psychoactive
drugs produce their effects, to a greater or less degree, by
interfering with the way the body produces those same effects
That means that the best hope
we can offer to the wishful thinkers out there who are still
looking for the "perfect drug" is to say that several
drugs -- including caffeine and alcohol -- seem relatively harmless,
when used in moderation, by most people.
But that's as close as any responsible
person can ever get to endorsing psychoactive chemicals.
That's because, in discussing
drugs and the body, it eventually becomes necessary to point
out that all bodies -- and all brains -- are not alike. Some
people tolerate caffeine well. Others go right up the wall after
a single cup of mocha latté.
Some people seem to be able to
drink regularly without major physical or behavioral impairment.
Others seem to be born drunks.
Where do you fit in the continuum?
Only you -- and your body -- can say.
Because what we know about drugs
and their effects to date basically centers around the ways in
which our bodies are alike. The problem is that we're all different.
And drugs and alcohol do their most serious work by plugging
into the most "different" parts of us all.
That's because psychoactive chemicals
move, like magnets to steel, to the places inside us where thoughts
and perceptions and feelings are born, live, and eventually die.
Perhaps most worrisome of all,
they tilt these intimate aspects of ourselves from the inside
From the outside in, though --
from the perspective of the altered self-concept and thoughts
and feelings that result -- it's easy to overlook the fact that
we're doing it to ourselves. And from there, it's a small step
to forgetting who's in charge of our lives altogether.
Want to avoid problems for yourself?
The safest way is to be careful
with the drugs you allow into your life.
Because one bit of information
that human beings picked up over the centuries that's as true
in the era of science as it was in the era of superstition is
that alcohol and drugs can change us -- in ways both large and
And the surest way to prevent
problems is to avoid them altogether.
The current explosion of research
into drug actions and effects -- and the expansion of awareness
it has provided into basic processes of human consciousness --
is one of the most remarkable stories of our time.
Developments are coming in so
quickly that it's impossible for any single edition of a single
publication -- especially one as brief as this one -- to provide
much more than a snapshot of the understanding of the present
For more information -- and an
in-depth analysis of topics covered in Drugs & the Body,
we recommend consulting the most recent edition of any of the
following works, which are invaluable guides to basic and advanced
principles of psychopharmacology.
A Primer of Drug Action. Robert
M. Julien, M.D., Ph.D., W.H. Freeman, 1995.
Drugs and the Brain. Solomon H. Snyder, M.D., Scientific American
Mind Matters: How the Mind and Brain Interact to Create Our Conscious
Lives. Michael S. Gazzaniga, Ph.D., Houghton-Mifflin, 1988.
The Biochemical Basis of Neuropharmacology. Jack R. Cooper, Ph.D.,
Floyd E. Bloom, M.D., and Robert H. Roth, Ph.D., Oxford University
For more information on the neurological
basis of drug actions and effects, please visit our web site