Thank you for inviting me to participate in this hearing. What I would like to do this
morning is illustrate through the use of some recent research findings what science has
come to teach us about one of our Nation's most
serious public health problems--drug abuse and addiction. I would like to point out at the
onset that the scientific advancements in the drug abuse and addiction field have been
coming at an extraordinary rate and are truly revolutionizing how we, both as a field of
science, and as a society, approach the complex problem of addiction.
We have learned a great deal about what drugs do to the brain in recent years. In fact,
we now know more about abused drugs and the brain than is known about almost any other
aspect of brain function. By building on this advanced understanding of addiction and by
utilizing emerging state-of-the-art technologies we can now actually see how brain
mechanisms work both under normal conditions and when affected by drugs of abuse. These
tools have allowed us to cast away the old popular belief held by many that addiction is
just a lot of drug use. It is not that simple. In fact, addiction is a chronic, and for
many people, reoccurring disease characterized by compulsive drug seeking and use that
results from the prolonged effects of drugs on the brain. These brain changes are
essentially what makes addiction a brain disease. This is a conclusion reached by not just
the researchers that my Institute supports, but by a number of other highly credible
research-oriented sources, such as the National Academy of Sciences Institute of Medicine
and the American Medical Association, among others. And as you yourselves will see
shortly, from the brain image posters that I brought, the addicted brain is in fact
different from the non-addicted brain.
What science has come to show as the "changed"brain of the addict is in fact what we have come to
believe causes the compulsion to use drugs. Once a person becomes addicted, they become
preoccupied with their quest for seeking and using drugs. The negative consequences that
may result from taking the drugs are no longer an important issue for them. It is the
behaviors that accompany this compulsion that are the elements responsible for the
enormous health and social problems that drug addiction brings in its wake. Drug abuse and
addiction have tremendous negative implications for not only the health of the individual,
but for the health of the public as well. Drug use, directly or indirectly, is a major
factor in crime and delinquency, work productivity, and is a vector for the spread of
HIV/AIDS and other serious infectious diseases. With the most recent estimate of the
economic burden for drug abuse estimated to exceed $109 billion, it is more imperative
than ever that we rely on research to develop effective prevention and treatment programs
that will reduce the burden of this disease. Science should also be the foundation for any
health and social policy decisions that are made regarding drug use.
Science has also given us a more insightful understanding of why people take drugs.
People use drugs for a variety of reasons. Some people take
drugs simply to have a novel or sensational experience. They take them for the experience
of modifying their mood, their perceptions, or their emotional state. But there is also
another group of people who take drugs for a different reason. Although they may take
drugs to modify their mood or their emotional state, they seem to be using drugs to help
them cope with their problems. These individuals are, in effect, self-medicating. Whatever
their initial motivation, people basically take drugs because drugs make them feel good or
better immediately, and this occurs because drugs essentially change the way the brain
functions. This is why we say that people take drugs because they like what they do to
However, the pleasurable effects do not last long. As the drug use continues, tolerance
to the drug often develops, meaning more frequent drug use is required for the brain to
register the same level of pleasure experienced during initial use. This often leads to
even more prolonged drug use. And as I mentioned earlier, prolonged drug use has been
found to cause pervasive changes in brain function.
This seems to be the case for almost every drug of abuse, including alcohol, nicotine,
marijuana, cocaine, heroin, and methamphetamine, a problem that has reached epidemic
proportions in many regions of the country. All of these drugs have been found to produce
noticeable changes in the brain. Regardless of the idiosyncratic effects that each drug
causes, all of these drugs have been found to elevate levels of the neurotransmitter
dopamine in the brain pathways that control reward and pleasure. It is this change in
dopamine that we have come to believe is a fundamental characteristic of all addictions.
Of course this is not to say that an individual has to abuse drugs for an entire
lifetime for drugs to be harmful to their brains and their bodies. Acute drug use can also
modify brain function in critical ways. The effects of cocaine, for example, appear
immediately after a single dose. It alters the brain so the individual feels euphoric and
mentally alert, especially to the sensation of sight, sound and touch. Cocaine use can
also constrict blood vessels, and increase heart rate and blood pressure. Even short-term
marijuana use, for example, can affect the brain, by modifying learning abilities, memory,
emotional state, perception, and motor coordination. Prolonged marijuana use has been
found to alter memory and learning processes, the brain, the lungs, and the immune system.
And of course chronic use can lead to addiction.
I would like to use two posters to illustrate how the brain of an addict differs from
those of a non- addict. Even more importantly, these images provide two dramatic examples
of the long lasting effects that drugs can have on the brain. These images are
particularly alarming given that both of these drugs, methamphetamine and MDMA or "Ecstasy"
are being used increasingly by young adults at levels that have been found to be toxic in
animals. These are the first direct images showing the effects of these drugs on the
brains of humans and the effects are the same as they were in animals.
Figure 1 shows images of two human brains. The one on top belongs to an individual who
has never used Ecstasy. The bottom images show the brain of an individual who had used
Ecstasy heavily for an extended period, but was abstinent from drugs for at least three
weeks prior to the study. Clearly the brain of the Ecstasy user on the bottom has been
significantly altered. The specific parameter being measured is the brain's ability to bind the chemical neurotransmitter
serotonin. Serotonin is critical to normal experiences of mood, emotion, pain, and a wide
variety of other behaviors. On the figure, brighter colors reflect greater serotonin
transporter binding; dull colors mean less binding capacity. This figure shows a decrease
in the Ecstasy user's ability to remove this
important neurotransmitter from the intracellular space, thereby amplifying its effects
within the brain. This decrease lasts at least three weeks after the individual has
stopped using Ecstasy. Given serotonin's
critical role in many behavioral characteristics, one can speculate that this abnormality
of the serotonin system might be responsible for some of Ecstasy's long-lasting behavioral effects.
Figure 2 also demonstrates the long-lasting effects that drugs can have on the brain.
Here you can see dopamine transporter binding in four different adults. Brighter colors
reflect greater dopamine binding capacity. The scan on the left is that of a non-drug
user, the next is of a chronic methamphetamine user who was drug free for about three
years when this image was taken, followed by a chronic methcathinone abuser who was also
drug free for about three years. The last image is of the brain of an individual newly
diagnosed with Parkinson's Disease, a disease
known to deplete dopamine in certain areas of the brain. When compared with the control on
the left, one can see the significant loss in the brain's
ability to transport dopamine back into brain cells. Dopamine function is critical to
emotional regulation, is involved in the normal experience of pleasure and is involved in
controlling an individual's motor function.
Thus, this long-lasting impairment in dopamine function might account for some of the
behavioral dysfunctions that persist after long-term methamphetamine use.
It is this type of scientific data that should be alarming to every citizen of this
Nation. Taking drugs is not something anyone should take lightly. Even occasional drug use
can be dangerous and there is no way to predict who may suffer drastic consequences
as a result of experimenting with drugs. Some people are just more sensitive to the
effects of drugs than others. Generally speaking, no one starts out in life saying they
want to grow up to be a drug addict. And I doubt that anyone thinks that their initial
decision to use drugs may be something that effects them the rest of their lives. They don't take into account that their occasional drug use
may be having an effect on their brain. And I don't
think anybody wants to intentionally give themselves a brain disease. These are some of
the reasons that as a scientist and a public health official, it is my responsibility to
inform people about what drugs can do to the brain. It is also my responsibility to inform
policy makers about the science of addiction so they are able to make policy decisions
that are in the public's best interests.
Thank you for the opportunity to testify at this hearing.