Addiction is a Brain Disease
By ALAN I. LESHNER, MD
A core concept evolving with scientific advances over the past
decade is that drug addiction is a brain disease that develops over
time as a result of the initially voluntary behavior of using
drugs. (Drugs include alcohol.)
The consequence is virtually uncontrollable compulsive drug
craving, seeking, and use that interferes with, if not destroys, an
individual’s functioning in the family and in society. This medical
condition demands formal treatment.
- We now know in great detail the brain mechanisms through which
drugs acutely modify mood, memory, perception, and emotional
states.
- Using drugs repeatedly over time changes brain structure and
function in fundamental and long-lasting ways that can persist
long after the individual stops using them.
- Addiction comes about through an array of neuro-adaptive
changes and the lying down and strengthening of new memory
connections in various circuits in the brain.
The High jacked Brain
We do not yet know all the relevant mechanisms, but the evidence
suggests that those long-lasting brain changes are responsible for
the distortions of cognitive and emotional
functioning that characterize addicts, particularly including
the compulsion to use drugs that is the essence of addiction.
It is as if drugs have high jacked the brain’s natural
motivational control circuits, resulting in drug use becoming the
sole, or at least the top, motivational priority for the individual.
Thus, the majority of the biomedical community now considers
addiction, in its essence, to be a brain disease:
This brain-based view of addiction has generated
substantial controversy, particularly among people who seem able to
think only in polarized ways.
- Many people erroneously still believe that biological and
behavioral explanations are alternative or competing ways to
understand phenomena, when if fact they are complementary and
integrative.
Modern science has taught that it is much too
simplistic to set biology in opposition to behavior or to pit
willpower against brain chemistry.
- Addiction involves inseparable biological and behavioral
components. It is the quintessential bio-behavioral disorder.
Many people also erroneously still believe that
drug addiction is simply a failure of will or of strength of
character. Research contradicts that position.
Responsible For Our Recovery
However, the recognition that addiction is a brain disease does
not mean that the addict is simply a hapless victim. Addiction
begins with the voluntary behavior of using drugs, and addicts must
participate in and take some significant responsibility for their
recovery.
- Thus, having this brain disease does not absolve the addict
of responsibility for his or her behavior.
But it does explain why an addict cannot simply stop
using drugs by sheer force of will alone.
The Essence of Addiction
The entire concept of addiction has suffered greatly from
imprecision and misconception. In fact, if it were possible, it
would be best to start all over with some new, more neutral term.
The confusion comes about in part because of a
now archaic distinction between whether specific drugs are
“physically” or “psychologically”addicting.
The distinction historically revolved around whether
or not dramatic physical withdrawal symptoms occur when an
individual stops taking a drug; what we in the field now call
“physical dependence.”
- However, 20 years of scientific research has taught that
focusing on this physical versus psychological distinction is
off the mark and a distraction from the real issues.
From both clinical and policy perspectives, it
actually does not matter very much what physical withdrawal symptoms
occur.
- Physical dependence is not that important, because even the
dramatic withdrawal symptoms of heroin and alcohol addiction can
now be easily managed with appropriate medications.
- Even more important, many of the most dangerous and
addicting drugs, including methamphetamine and crack cocaine, do
not produce very severe physical dependence symptoms upon
withdrawal.
What really matters most is whether or not a drug
causes what we now know to be the essence of addiction, namely
- The uncontrollable, compulsive drug craving,
seeking, and use, even in the face of negative health and social
consequences.
This is the crux of how the Institute of Medicine,
the American Psychiatric Association, and the American Medical
Association define addiction and how we all should use the term.
It is really only this compulsive quality of
addiction that matters in the long run to the addict and to his or
her family and that should matter to society as a whole.
Thus, the majority of the biomedical community now
considers addiction, in its essence, to be a brain disease:
- A condition caused by persistent changes in
brain structure and function.
This results in compulsive craving that overwhelms
all other motivations and is the root cause of the massive health
and social problems associated with drug addiction.
The Definition of Addiction
In updating our national discourse on drug abuse, we should keep
in mind this simple definition:
- Addiction is a brain disease expressed in the
form of compulsive behavior.
Both developing and recovering from it depend on
biology, behavior, and social context.
It is also important to correct the common
misimpression that drug use, abuse and addiction are points on a
single continuum along which on slides back and forth over time,
moving from user to addict, then back to occasional user, then back
to addict.
Clinical observation and more formal
research studies support the view that, once addicted, the
individual has moved into a different state of being.
- It is as if a threshold has been crossed.
Very few people appear able to successfully
return to occasional use after having been truly addicted.
The Altered Brain - A Chronic
Illness
Unfortunately, we do not yet have a clear biological or
behavioral marker of that transition from voluntary drug use to
addiction.
However, a body of scientific evidence is rapidly
developing that points to an array of cellular and molecular changes
in specific brain circuits. Moreover, many of these brain changes
are common to all chemical addictions, and some also are typical of
other compulsive behaviors such as pathological overeating.
- Addiction should be understood as a chronic recurring
illness.
- Although some addicts do gain full control over their drug
use after a single treatment episode, many have relapses.
The complexity of this brain disease is not
atypical, because virtually no brain diseases are simply biological
in nature and expression. All, including stroke, Alzheimer's
disease, schizophrenia, and clinical depression, include some
behavioral and social aspects.
What may make addiction seem unique among brain
diseases, however, is that it does begin with a clearly voluntary
behavior- the initial decision to use drugs. Moreover, not everyone
who ever uses drugs goes on to become addicted.
- Individuals differ substantially in how easily
and quickly they become addicted and in their preferences for
particular substances.
Consistent with the bio-behavioral nature of
addiction, these individual differences result from a combination of
environmental and biological, particularly genetic, factors.
In fact, estimates are that between 50 and 70
percent of the variability in susceptibility to becoming addicted
can be accounted for by genetic factors. Although genetic
characteristics may predispose individuals to be more or less
susceptible to becoming addicted, genes do not doom one to become an
addict.
- Over time the addict loses substantial control over his or
her initially voluntary behavior, and it becomes compulsive.
For many people these behaviors are truly uncontrollable, just
like the behavioral expression of any other brain disease.
Schizophrenics cannot control their hallucinations
and delusions. Parkinson’s patients cannot control their
trembling. Clinically depressed patients cannot voluntarily control
their moods.
Thus, once one is addicted, the characteristics of
the illness- and the treatment approaches- are not that different
from most other brain diseases. No mater how one develops an
illness, once one has it, one is in the diseased state and needs
treatment.
Environmental Cues
Addictive behaviors do have special characteristics related to
the social contexts in which they originate.
- All of the environmental cues surrounding initial drug use
and development of the addiction actually become “conditioned”
to that drug use and are thus critical to the development and
expression of addiction.
Environmental cues are paired in time with an
individual’s initial drug use experiences and, through classical
conditioning, take on conditioned stimulus properties.
- When those cues are present at a later time, they elicit
anticipation of a drug experience and thus generate tremendous
drug craving.
Cue-induced craving is one of the most frequent
causes of drug use relapses, even after long periods of abstinence,
independently of whether drugs are available.
The salience of environmental or contextual cues
helps explain why reentry to one’s community can be so difficult for
addicts leaving the controlled environments of treatment or
correctional settings and why aftercare is so essential to
successful recovery.
- The person who became addicted in the home environment is
constantly exposed to the cues conditioned to his or her initial
drug use, such as the neighborhood where he or she hung out,
drug-using buddies, or the lamppost where he or she bought
drugs.
- Simple exposure to those cues automatically triggers craving
and can lead rapidly to relapses.
This is one reason why someone who apparently
overcame drug cravings while in prison or residential treatment
could quickly revert to drug use upon returning home.
In fact, one of the major goals of
drug addiction treatment is to teach addicts how to deal with the
cravings caused by inevitable exposure to these conditioned cues.
Implications
It is no wonder addicts cannot simply quit on their own.
They have an illness that requires biomedical
treatment.
- People often assume that because addiction begins with a
voluntary behavior and is expressed in the form of excess
behavior, people should just be able to quit by force of will
alone.
- However, it is essential to understand when dealing with
addicts that we are dealing with individuals whose brains have
been altered by drug use.
They need drug addiction treatment.
We know that, contrary to common
belief, very few addicts actually do just stop on their own.
Observing that there are very few heroin addicts in
their 50s or 60s, people frequently ask what happened to those who
were heroin addicts 30 years ago, assuming that they must have quit
on their own.
- However, longitudinal studies find that only a very small
fraction actually quit on their own. The rest have either been
successfully treated, are currently in maintenance treatment, or
(for about half) are dead.
Consider the example of smoking cigarettes: Various
studies have found that between 3 and 7 percent of people who try to
quit on their own each year actually succeed.
Science has at last convinced the public that
depression is not just a lot of sadness; that depressed individuals
are in a different brain state and thus require treatment to get
their symptoms under control. It is time to recognize that this is
also the case for addicts.
The Role of Personal Responsibility
The role of personal responsibility is undiminished but
clarified.
Does having a brain disease mean that people who are
addicted no longer have any responsibility for their behavior or
that they are simply victims of their own genetics and brain
chemistry? Of course not.
Addiction begins with the voluntary behavior of drug
use, and although genetic characteristics may predispose individuals
to be more or less susceptible to becoming addicted, genes do not
doom one to become an addict.
This is one major reason why efforts to prevent drug
use are so vital to any comprehensive strategy to deal with the
nation’s drug problems. Initial drug use is a voluntary, and
therefore preventable, behavior.
Moreover, as with any illness, behavior becomes a
critical part of recovery. At a minimum, one must comply with the
treatment regimen, which is harder that it sounds.
- Treatment compliance is the biggest cause of relapses for
all chronic illnesses, including asthma, diabetes, hypertension,
and addiction.
- Moreover, treatment compliance rates are no worse for
addiction than for these other illnesses, ranging from 30 to 50
percent.
Thus, for drug addiction as well as for other
chronic diseases, the individual’s motivation and behavior are
clearly important parts of success in treatment and recovery.
Alcohol/ Drug Treatment Programs
Maintaining this comprehensive bio-behavioral understanding of
addiction also speaks to what needs to be provided in drug treatment
programs.
- Again, we must be careful not to pit biology against
behavior.
The National Institute on Drug Abuse’s recently
published Principles of Effective Drug Addiction Treatment provides
a detailed discussion of how we must treat all aspects of the
individual, not just the biological component or the behavioral
component.
As with other brain diseases such as schizophrenia
and depression, the data show that the best drug addiction treatment
approaches attend to the entire individual, combining the use of
medications, behavioral therapies, and attention to necessary social
services and rehabilitation.
- These might include such services as family therapy to
enable the patient to return to successful family life, mental
health services, education and vocational training, and housing
services.
That does not mean, of course, that all individuals
need all components of treatment and all rehabilitation services.
Another principle of effective addiction treatment is that the array
of services included in an individual's treatment plan must be
matched to his or her particular set of needs. Moreover, since those
needs will surely change over the course of recovery, the array of
services provided will need to be continually reassessed and
adjusted.
We believe holistic approaches ranging from brain
wave biofeedback to yoga and acupunture are an important part of
the "array of services" to which he refers.
Recommended Reading
J. D. Berke and S. E. Hyman, "Addiction,
Dopamine, and the Molecular Mechanisms of Memory," Neuron 25
(2000): 515~532 (http://www.neuron.org/cgi/content/full/25/3/515/).
H. Garavan, J. Pankiewicz, A. Bloom, J. K. Cho, L.
Sperry, T. J. Ross, B. J. Salmeron, R. Risinger, D. Kelley, and E.
A. Stein, "Cue-Induced
Cocaine Craving: Neuroanatomical Specificity for Drug Users and Drug
Stimuli," American Journal of Psychiatry 157 (2000): 1789~1798
(http://ajp.psychiatryonline.org/cgi/content/full/157/11/1789).
A. I. Leshner, "Science-Based
Views of Drug Addiction and Its Treatment," Journal of the
American Medical Association 282 (1999): 1314~1316
(http://jama.ama-assn.org/issues/v282n14/rfull/jct90020.html).
A. T. McLellan, D. C. Lewis, C. P. O'Brien, and H.
D. Kleber, "Drug
Dependence, a Chronic Medical Illness," Journal of the American
Medical Association 284 (2000): 1689~1695 (http://jama.ama-assn.org/issues/v284n13/rfull/jsc00024.html).
National Institute on Drug Abuse, Principles of Drug Addiction
Treatment: A Research-Based Guide (National Institutes of
Health, Bethesda, MD, July 2000) (http://165.112.78.61/PODAT/PODATindex.html).
National Institute on Drug Abuse, Preventing Drug Use Among Children
and Adolescents: A Research-Based Guide (National Institutes of
Health, Bethesda, MD, March 1997) (http://165.112.78.61/Prevention/Prevopen.html).
E. J. Nestler, "Genes
and Addiction," Nature Genetics 26 (2000): 277~281 (http://www.nature.com/cgi-taf/DynaPage.taf?file=/ng/journal/v26/n3/full/ng1100_277.html).
Physician Leadership on National Drug Policy, position paper on
drug policy (PLNDP Program Office, Brown University, Center for
Alcohol and Addiction Studies, Providence, R.I.: January 2000)
(http://center.butler.brown.edu/plndp/Resources/resources.html).
F. S. Taxman and J. A. Bouffard, "The Importance of
Systems in Improving Offender Outcomes: New Frontiers in Treatment
Integrity," Justice Research and Policy 2 (2000): 37~58.
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