The abuse of methamphetamine - a potent and highly addictive
psychostimulant - is a very serious problem in the United States.
Initially limited to Hawaii and western parts of the country,
methamphetamine abuse continues to spread eastward, with rural and
urban areas everywhere increasingly affected. According to one
national survey, approximately 10 million people in the United
States have tried methamphetamine at least once.
Methamphetamine abuse leads to devastating medical, psychological,
and social consequences. Adverse health effects include memory loss,
aggression, psychotic behavior, heart damage, malnutrition, and
severe dental problems. Methamphetamine abuse also contributes to
increased transmission of infectious diseases, such as hepatitis and
HIV/AIDS, and can infuse whole communities with new waves of crime,
unemployment, child neglect or abuse, and other social ills.
The good news is that methamphetamine abuse can be prevented and
methamphetamine addiction can be treated. People do recover, but
only when effective treatments that address the multitude of
problems resulting from methamphetamine abuse are readily available.
Primary goals of the National Institute on Drug Abuse (NIDA) are to
apply what our scientists learn from drug abuse research to develop
new and enhance existing treatment approaches and to bring these
effective treatments to the communities that need them.
In this report, we provide an overview of the latest scientific
findings on methamphetamine. Our intent is to enlighten readers
about the damaging effects of methamphetamine abuse and to inform
prevention and treatment efforts.
Nora D.Volkow, M.D.
Director
National Institute on Drug Abuse
Methamphetamine is a highly addictive
stimulant that affects the central nervous system. Although most of
the methamphetamine used in this country comes from foreign or
domestic superlabs, the drug is also easily made in small
clandestine laboratories, with relatively inexpensive
over-the-counter ingredients. These factors combine to make
methamphetamine a drug with high potential for widespread abuse.
Methamphetamine is commonly known as "speed," "meth," and "chalk."
In its smoked form, it is often referred to as "ice," "crystal,"
"crank," and "glass." It is a white, odorless, bitter-tasting
crystalline powder that easily dissolves in water or alcohol. The
drug was developed early last century from its parent drug,
amphetamine, and was used originally in nasal decongestants and
bronchial inhalers. Like amphetamine, methamphetamine causes
increased activity and talkativeness, decreased appetite, and a
general sense of well-being. However, methamphetamine differs from
amphetamine in that at comparable doses, much higher levels of
methamphetamine get into the brain, making it a more potent
stimulant drug. It also has longer lasting and more harmful effects
on the central nervous system.
Methamphetamine
Methamphetamine is a Schedule II stimulant, which means it has a
high potential for abuse and is available only through a
prescription. It is indicated for the treatment of narcolepsy (a
sleep disorder) and attention deficit hyperactivity disorder; but
these medical uses are limited, and the doses are much lower than
those typically abused.
NIDA's Community Epidemiology Work
Group (CEWG), an early warning network of researchers that provides
information about the nature and patterns of drug abuse in 21 major
areas of the U.S., reported in January 2006 that methamphetamine
continues to be a problem in the West, with indicators persisting at
high levels in Honolulu, San Diego, Seattle, San Francisco, and Los
Angeles; and that it continues to spread to other areas of the
country, including both rural and urban sections of the South and
Midwest. In fact, methamphetamine was reported to be the fastest
growing problem in metropolitan Atlanta.
Primary Methamphetamine/Amphetamine Admission Rates per 100,000
Population Aged 12 and Over
According to the 2005 National Survey on Drug Use and Health (NSDUH),
an estimated 10.4 million people age 12 or older (4.3 percent of the
population) have tried methamphetamine at some time in their lives.
Approximately 1.3 million reported past-year methamphetamine use,
and 512,000 reported current (past-month) use. Moreover, the 2005
Monitoring the Future (MTF) survey of student drug use and attitudes
reported 4.5 percent of high school seniors had used methamphetamine
within their lifetimes, while 8th-graders and 10th-graders reported
lifetime use at 3.1 and 4.1 percent, respectively. However, neither
of these surveys has documented an overall increase in the abuse of
methamphetamine over the past few years. In fact, both surveys
showed recent declines in methamphetamine abuse among the Nation's
youth.
In contrast, evidence from emergency departments and treatment
programs attest to the growing impact of methamphetamine abuse in
the country. The Drug Abuse Warning Network (DAWN), which collects
information on drug-related episodes from hospital emergency
departments (EDs) throughout the Nation, has reported a greater than
50 percent increase in the number of ED visits related to
methamphetamine abuse between 1995 and 2002, reaching approximately
73,000 ED visits, or 4 percent of all drug-related visits in 2004.
Treatment admissions for methamphetamine abuse have also increased
substantially. In 1992, there were approximately 21,000 treatment
admissions in which methamphetamine/amphetamine was identified as
the primary drug of abuse, representing more than 1 percent of all
treatment admissions during the year. By 2004, the number of
methamphetamine treatment admissions increased to greater than
150,000, representing 8 percent of all admissions.
Moreover, this increased involvement of methamphetamine in drug
treatment admissions has also been spreading across the country. In
1992, only 5 states reported high rates of treatment admissions
(i.e., >24 per 100,000 population) for primary
methamphetamine/amphetamine problems; by 2002, this number increased
to 21, more than a third of the states.
Methamphetamine comes in many forms
and can be smoked, snorted, injected, or orally ingested. The
preferred method of methamphetamine abuse varies by geographical
region and has changed over time. Smoking methamphetamine, which
leads to very fast uptake of the drug in the brain, has become more
common in recent years, amplifying methamphetamine's addiction
potential and adverse health consequences.
The drug also alters mood in different ways, depending on how it is
taken. Immediately after smoking the drug or injecting it
intravenously, the user experiences an intense rush or "flash" that
lasts only a few minutes and is described as extremely pleasurable.
Snorting or oral ingestion produces euphoria - a high but not an
intense rush. Snorting produces effects within 3 to 5 minutes, and
oral ingestion produces effects within 15 to 20 minutes.
As with similar stimulants, methamphetamine most often is used in a
"binge and crash" pattern. Because the pleasurable effects of
methamphetamine disappear even before the drug concentration in the
blood falls significantly - users try to maintain the high by taking
more of the drug. In some cases, abusers indulge in a form of
binging known as a "run," foregoing food and sleep while continuing
abuse for up to several days.
Methamphetamine is structurally
similar to amphetamine and the neurotransmitter dopamine, but it is
quite different from cocaine. Although these stimulants have similar
behavioral and physiological effects, there are some major
differences in the basic mechanisms of how they work. In contrast to
cocaine, which is quickly removed and almost completely metabolized
in the body, methamphetamine has a much longer duration of action
and a larger percentage of the drug remains unchanged in the body.
This results in methamphetamine being present in the brain longer,
which ultimately leads to prolonged stimulant effects. And although
both methamphetamine and cocaine increase levels of the brain
chemical dopamine, animal studies reveal much higher levels of
dopamine following administration of methamphetamine due to the
different mechanisms of action within nerve cells in response to
these drugs. Cocaine prolongs dopamine actions in the brain by
blocking dopamine re-uptake. While at low doses, methamphetamine
blocks dopamine re-uptake, methamphetamine also increases the
release of dopamine, leading to much higher concentrations in the
synapse, which can be toxic to nerve terminals.
As a powerful stimulant,
methamphetamine, even in small doses, can increase wakefulness and
physical activity and decrease appetite. Methamphetamine can also
cause a variety of cardiovascular problems, including rapid heart
rate, irregular heartbeat, and increased blood pressure.
Hyperthermia (elevated body temperature) and convulsions may occur
with methamphetamine overdose, and if not treated immediately, can
result in death.
Most of the pleasurable effects of methamphetamine are believed to
result from the release of very high levels of the neurotransmitter
dopamine. Dopamine is involved in motivation, the experience of
pleasure, and motor function, and is a common mechanism of action
for most drugs of abuse. The elevated release of dopamine produced
by methamphetamine is also thought to contribute to the drug's
deleterious effects on nerve terminals in the brain.
Dopamine Pathways
In the brain, dopamine plays an important role in the regulation of
reward and movement. As part of the reward pathway, dopamine is
manufactured in nerve cell bodies located within the ventral
tegmental area (VTA) and is released in the nucleus accumbens and
the prefrontal cortex. Its motor functions are linked to a separate
pathway, with cell bodies in the substantia nigra that manufacture
and release dopamine into the striatum.
Long-term methamphetamine abuse has
many negative consequences, including addiction. Addiction is a
chronic, relapsing disease, characterized by compulsive drug seeking
and use, accompanied by functional and molecular changes in the
brain. In addition to being addicted to methamphetamine, chronic
abusers exhibit symptoms that can include anxiety, confusion,
insomnia, mood disturbances, and violent behavior. They also can
display a number of psychotic features, including paranoia, visual
and auditory hallucinations, and delusions (for example, the
sensation of insects creeping under the skin). Psychotic symptoms
can sometimes last for months or years after methamphetamine abuse
has ceased, and stress has been shown to precipitate spontaneous
recurrence of methamphetamine psychosis in formerly psychotic
methamphetamine abusers.
With chronic abuse, tolerance to methamphetamine's pleasurable
effects can develop. In an effort to intensify the desired effects,
abusers may take higher doses of the drug, take it more frequently,
or change their method of drug intake. Withdrawal from
methamphetamine occurs when a chronic abuser stops taking the drug;
symptoms of withdrawal include depression, anxiety, fatigue, and an
intense craving for the drug.
Recovery of Brain Dopamine Transporters in Chronic Methamphetamine (METH)
Abusers
Chronic methamphetamine abuse also significantly changes the brain.
Specifically, brain imaging studies have demonstrated alterations in
the activity of the dopamine system that are associated with reduced
motor speed and impaired verbal learning. Recent studies in chronic
methamphetamine abusers have also revealed severe structural and
functional changes in areas of the brain associated with emotion and
memory, which may account for many of the emotional and cognitive
problems observed in chronic methamphetamine abusers.
Fortunately, some of the effects of chronic methamphetamine abuse
appear to be, at least partially, reversible. A recent neuroimaging
study showed recovery in some brain regions following prolonged
abstinence (2 years, but not 6 months). This was associated with
improved performance on motor and verbal memory tests. However,
function in other brain regions did not display recovery even after
2 years of abstinence, indicating that some methamphetamine-induced
changes are very long-lasting. Moreover, the increased risk of
stroke from the abuse of methamphetamine can lead to irreversible
damage to the brain.
Short-term effects may include:
Increased attention and decreased fatigue
Increased activity and wakefulness
Decreased appetite
Euphoria and rush
Increased respiration
Rapid/irregular heartbeat
Hyperthermia
Long-term effects may include:
Addiction
Psychosis, including:
paranoia
hallucinations
repetitive motor activity
Changes in brain structure and function
Memory Loss
Aggressive or violent behavior
Mood disturbances
Severe dental problems
Weight loss
Prenatal exposure to methamphetamine
may also be a problem in the United States. Although according to
the NSDUH, less than 1 percent of pregnant women aged 15-44 had used
methamphetamine in the past year, any use among this population is
of concern. Unfortunately, our knowledge of the effects of
methamphetamine during pregnancy is limited. The few human studies
that exist have shown increased rates of premature delivery,
placental abruption, fetal growth retardation, and heart and brain
abnormalities. However, these studies are difficult to interpret due
to methodological issues, such as small sample size and maternal use
of other drugs. Ongoing research is continuing to study
developmental outcomes such as cognition, social relationships,
motor skills, and medical status of children exposed to
methamphetamine before birth.
Increased HIV and hepatitis B and C
transmission are consequences of increased methamphetamine abuse,
not only in individuals who inject the drug, but also in
noninjecting methamphetamine abusers. Among injection drug users,
infection with HIV and other infectious diseases is spread primarily
through the re-use of contaminated syringes, needles, or other
paraphernalia by more than one person. However, regardless of how it
is taken, the intoxicating effects of methamphetamine can alter
judgment and inhibition and lead people to engage in unsafe
behaviors.
Methamphetamine has become associated with a culture of risky sexual
behavior, both among men who have sex with men (MSM) and
heterosexual populations. This link may be due to the fact that
methamphetamine and related psychomotor stimulants can increase
libido. Paradoxically, long-term methamphetamine abuse may be
associated with decreased sexual functioning, at least in men. The
combination of injection and sexual risk-taking may result in HIV
becoming a greater problem among methamphetamine abusers than among
opiate and other drug abusers, something that already seems to be
occurring, according to some epidemiologic reports. For example,
while the link between HIV infection and methamphetamine abuse has
not yet been established for heterosexuals, data show an association
between methamphetamine abuse and the spread of HIV among MSM.
Methamphetamine abuse may also worsen the progression of HIV and its
consequences. In animal studies, methamphetamine increased viral
replication; in human methamphetamine abusers, HIV caused greater
neuronal injury and cognitive impairment compared with nondrug
abusers.
NIDA-funded research has found that, through drug abuse treatment,
prevention, and community-based outreach programs, drug abusers can
change their HIV risk behaviors. Drug abuse can be eliminated and
drug-related risk behaviors, such as needle-sharing and unsafe
sexual practices, can be reduced significantly, thus decreasing the
risk of exposure to HIV and other infectious diseases. Therefore,
drug abuse treatment is HIV prevention.
At this time, the most effective
treatments for methamphetamine addiction are behavioral therapies
such as cognitive behavioral and contingency management
interventions. For example, the Matrix Model, a comprehensive
behavioral treatment approach that combines behavioral therapy,
family education, individual counseling, 12-Step support, drug
testing, and encouragement for nondrug-related activities, has been
shown to be effective in reducing methamphetamine abuse. Contingency
management interventions, which provide tangible incentives in
exchange for engaging in treatment and maintaining abstinence, have
also been shown to be effective.
There are currently no specific medications that counteract the
effects of methamphetamine or that prolong abstinence from and
reduce the abuse of methamphetamine by an individual addicted to the
drug. However, there are a number of medications that are
FDA-approved for other illnesses that might also be useful in
treating methamphetamine addiction. Recent study findings reveal
that bupropion, the anti-depressant marketed as Wellbutrin, reduced
the methamphetamine-induced "high" as well as drug cravings elicited
by drug-related cues. This medication and others are currently in
clinical trials, while new compounds are being developed and studied
in preclinical models.
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