The D.S.M. Gets Addiction Right
By HOWARD MARKEL
Published: June 5, 2012
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WHEN we say that someone is “addicted” to a behavior like gambling
or eating or playing video games, what does that mean? Are such
compulsions really akin to dependencies like drug and alcohol addiction —
or is that just loose talk?
This question arose recently after the committee writing the latest
edition of the Diagnostic and Statistical Manual of Mental Disorders
(D.S.M.), the standard reference work for psychiatric illnesses,
announced updated definitions of substance abuse
and addiction, including a new category of “behavioral addictions.” At
the moment, the only disorder featured in this new category is
pathological gambling, but the suggestion is that other behavioral
disorders will be added in due course. Internet addiction, for instance,
was initially considered for inclusion but was relegated to an appendix
(as was sex addiction) pending further research.
Skeptics worry that such broad criteria for addiction will pathologize
normal (if bad) behavior and lead to overdiagnosis and overtreatment.
Allen J. Frances, a professor of psychiatry
and behavioral sciences at Duke University who has worked on the
D.S.M., has said that the new definitions amount to “the medicalization
of everyday behavior” and will create “false epidemics.” Health insurance
companies are fretting that the new diagnostic criteria may cost the
health care system hundreds of millions of dollars annually, as
addiction diagnoses multiply.
There is always potential for misuse when diagnostic criteria are
expanded. But on the key scientific point, the D.S.M.’s critics are
wrong. As anyone familiar with the history of the diagnosis of addiction
can tell you, the D.S.M.’s changes accurately reflect our evolving
understanding of what it means to be an addict.
The concept of addiction has been changing and expanding for centuries.
Initially, it wasn’t even a medical notion. In ancient Rome, “addiction”
referred to a legal dependency: the bond of slavery that lenders
imposed upon delinquent debtors. From the second century A.D. well into
the 1800s, “addiction” described a disposition toward any number of
obsessive behaviors, like excessive reading and writing or slavish
devotion to a hobby. The term often implied a weakness of character or a
moral failing.
“Addiction” entered the medical lexicon only in the late 19th century,
as a result of the over-prescription of opium and morphine by
physicians. Here, the concept of addiction came to include the notion of
an exogenous substance taken into the body. Starting in the early 20th
century, another key factor in diagnosing addiction was the occurrence
of physical withdrawal symptoms upon quitting the substance in question.
This definition of addiction was not always carefully applied (it took years for alcohol and nicotine to be classified as addictive, despite their fitting the bill), nor did it turn out to be accurate. Consider marijuana:
in the 1980s, when I was training to become a doctor, marijuana was
considered not to be addictive because the smoker rarely developed
physical symptoms upon stopping. We now know that for some users
marijuana can be terribly addictive, but because clearance of the drug
from the body’s fat cells takes weeks (instead of hours or days),
physical withdrawal rarely occurs, though psychological withdrawal
certainly can.
Accordingly, most doctors have accepted changes to the definition of
addiction, but many still maintain that only those people who
compulsively consume an exogenous substance can be called addicts. Over
the past several decades, however, a burgeoning body of scientific
evidence has indicated that an exogenous substance is less important to
addiction than is the disease process that the substance triggers in the
brain — a process that disrupts the brain’s anatomical structure,
chemical messaging system and other mechanisms responsible for governing
thoughts and actions.
For example, since the early 1990s, the neuropsychologists Kent C.
Berridge and Terry E. Robinson at the University of Michigan have
studied the neurotransmitter dopamine,
which gives rise to feelings of craving. They have found that when you
repeatedly take a substance like cocaine, your dopamine system becomes
hyper-responsive, making the drug extremely difficult for the addicted
brain to ignore. Though the drug itself plays a crucial role in starting
this process, the changes in the brain persist long after an addict
goes through withdrawal: drug-using cues and memories continue to elicit
cravings even in addicts who have abstained for years.
Furthermore, a team of scientists led by Nora Volkow at the National
Institute on Drug Abuse have used positron emission tomography (PET)
scans to show that even when cocaine addicts merely watch videos of
people using cocaine, dopamine levels increase in the part of their
brains associated with habit and learning. Dr. Volkow’s group and other
scientists have used PET scans and functional magnetic resonance imaging
to demonstrate similar dopamine receptor derangements in the brains of
drug addicts, compulsive gamblers and overeaters who are markedly obese.
The conclusion to draw here is that though substances like cocaine are
very effective at triggering changes in the brain that lead to addictive
behavior and urges, they are not the only possible triggers: just about
any deeply pleasurable activity — sex, eating, Internet use — has the
potential to become addictive and destructive.
Disease definitions change over time because of new scientific evidence.
This is what has happened with addiction. We should embrace the new
D.S.M. criteria and attack all the substances and behaviors that inspire
addiction with effective therapies and support.
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