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NIDA Media Advisories (continued)


[1996 Advisories][1995 Advisories]

Index of 1996 Advisories

For Immediate Release: October 10, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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Scientists Discover New Brain System That Counters Effects of Opioid Drugs

Researchers funded by the National Institute on Drug Abuse (NIDA) have discovered a neuronal system in the brain that modulates and opposes the action of the brain's own opioid system. The discovery of the actions of orphanin FQ (OFQ), a natural brain chemical, could provide the foundation for the development of effective pain-killing drugs without some of their negative side effects. These latest findings by Dr. David K. Grandy and colleagues at the Oregon Health Sciences University, appeared in the October 3, 1996 issue of Neuroscience.

According to Alan I. Leshner, Ph.D., Director of NIDA, "This discovery opens up a new avenue of research in the development of medications that maximize the pain relieving qualities of drugs such as morphine -- critical in the treatment of cancer patients, for example -- while minimizing their negative effects. Additionally, this research may eventually help us to further understand how and why individuals develop drug tolerance and experience unpleasant withdrawal symptoms," Dr. Leshner added.

While morphine is the principal drug used for controlling severe pain for patients after surgery, it can cause such undesirable effects as nausea, constipation, respiratory problems, and physical dependence.

This new evidence that OFQ and its receptor may play a role in opioid function may lead to new research exploring balance or homeostasis of the opioid system. If there is an imbalance or overactivity in one part of the brain, a compensatory change usually occurs to counterbalance it. These new findings raise interesting possibilities for developing therapeutic agents that act to compensate for the effects of the OFQ receptor. "Therapeutic drugs designed to block OFQ receptors may allow physicians to use less morphine to relieve pain because the endogenous system opposing morphine's actions would be blocked. We are hoping that an antagonist to the OFQ receptor will make morphine more efficacious so patients could benefit from its pain relieving effects without experiencing the unwanted side effects," Dr. Grandy said. He added that blocking the OFQ receptor may decrease the irritability, anxiety and nausea characteristic of heroin withdrawal.

This work was supported by NIDA, the National Institute on Neurological Diseases and Stroke, and the National Institute on Alcohol Abuse and Alcoholism, all components of the National Institutes of Health. NIDA is the primary Federal agency for the conduct and support of research to increase knowledge and develop strategies to deal with the health problems and issues associated with drug abuse and addiction. NIDA has been supporting the study of opiates since its inception because of their role as the most powerfully effective analgesics.

For additional information on this study and other NIDA research, call the NIDA Press Office at (301) 443-6245. Copies of NIDA Media Advisories and other information are available on the Home Page at http://www.nida.nih.gov.


For Immediate Release: October 7, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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Chronic Morphine Use Produces Visible Changes in Brain Cells

The National Institute on Drug Abuse (NIDA) today announced the results of a study that provides the first direct evidence that long-term, chronic opiate exposure is associated with structural changes in both the size and shape of specific neurons in the brain.

In previous studies, scientists have shown that chronic exposure to opiates causes dramatic biochemical changes in brain cells, which could contribute to the intense craving for drugs during withdrawal states. Now, researchers at the Yale University School of Medicine in New Haven, Conn., report in the October 1, 1996, issue of the Proceedings of the National Academy of Sciences, that rats chronically exposed to morphine also experienced marked structural changes in the dopamine neurons in the brain's ventral tegmental area (VTA).

"This brain area is activated during the use or self-administration of virtually all drugs of abuse." said NIDA Director, Alan I. Leshner, Ph.D. "We now know that prolonged drug use produces both structural and functional changes in critical brain circuits. The next step is to determine exactly what those changes mean and how they might be addressed in the devel- opment of new medications for the treatment of the long-term consequences of opiate use."

Researchers implanted rats with pellets of morphine or placebo for 5 days to induce morphine tolerance and dependence. At the same time, some rats were administered naltrexone or BDNF, a brain-derived neurotrophic factor. Naltrexone has been shown to block the development of morphine tolerance and dependence, and BDNF has been shown to prevent many of the biochemical effects of morphine in the brain.

The research demonstrates that chronic morphine administration produces a dramatic decrease in the size of mesolimbic dopamine neurons originating in the VTA. This is accompanied by a change in the shape of the neurons as well as their processes.

Importantly, while changes were observed in the one type of VTA neurons, dopamine neurons, no changes were observed in nondopaminergic neurons. And earlier studies have shown the importance of dopamine in the control and experience of drug use. Thus, the opioids are affecting exactly those brain cells involved in continuing drug use.

This study was directed by Dr. Eric J. Nestler, the Elizabeth Mears and House Jameson Professor of Psychiatry and Pharmacology at Yale. Dr. Nestler says that "While there was no evidence that chronic drug exposure killed the dopamine neurons, these findings clearly demonstrate the dramatic types of changes that drugs of abuse produce in selected brain regions that we believe underlie addiction. Given the prominence of these changes, it is no surprise that effective treatment of addictive disorders for most people would have to include treatments to undo or compensate for these biological changes."

This research was funded by the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health. NIDA is the primary Federal agency for the conduct and support of research to increase knowledge and develop strategies to deal with the health problems and issues associated with drug abuse and addiction. The research was carried out in the Abraham Ribicoff Research Facilities of the Connecticut Mental Health Center, which is a collaborative program of Yale University and the State of Connecticut Department of Mental Health and Addiction Services.

For additional information on this study and other NIDA research, contact the NIDA Press Office at (301) 443-6245. NIDA Media Advisories and other information are available on the Home Page at http://www.nida.nih.gov.


For Immediate Release: June 7, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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New Research May Explain Mechanism of Abnormalities in Offspring Prenatally Exposed to Cocaine

The National Institute on Drug Abuse (NIDA), National Institutes of Health, and researchers at the University of Massachusetts, today announced the results of experiments that provide strong evidence that cocaine interacts directly with specific cocaine receptors in the fetal rat brain. Although prenatal cocaine exposure has been shown to produce later behavioral deficits in human and animal offspring, little has been known about the mechanisms underlying those effects.

In commenting on the importance of these results, Dr. Alan I. Leshner, Director of NIDA said, "The finding that the fetal rat brain contains specific binding sites for cocaine is truly significant because it establishes an important concept that previously had only been hypothesized. Using this animal model to further investigate the interactions of cocaine with these sites in the brain and their consequences can yield important insights into the mechanisms by which cocaine may affect the health and development of human newborns who are exposed to the drug during pregnancy."

Because the second trimester of human pregnancy roughly corresponds to the latter part of the rat's gestation cycle, researchers hypothesized that these experiments with rats would help them to understand how cocaine affects the brain of a human fetus.

By conducting a series of experiments with rats, researchers discovered cocaine recognition sites in the fetal brain. These sites were located in areas of the brain that are involved in learning, memory, motivation, motor control, and sensory processing.

"This study demonstrated the presence of cocaine receptors in the fetal brain of rats and showed that cocaine is able to act directly on these receptors. This may explain some of the problems seen in human newborns exposed to cocaine during pregnancy, such as excessive irritability and later cognitive problems," said Dr. Jerrold S. Meyer, the Principal Investigator of the study.

Prenatal cocaine exposure often has been linked to behavioral and cognitive deficiencies in newborns, but until now, scientists have not understood how cocaine actually causes this to happen. It was thought that the effects of cocaine on the fetus may have been due to constriction of placental blood vessels, resulting in reduced supply of oxygen to the fetus. With this new information, researchers may be able to pinpoint the specific sites in the developing fetal brain that are most vulnerable to cocaine.

This study, authored by Lauren P. Shearman, Lucille M. Collins and Jerrold S. Meyer, will appear in the June issue of the Journal of Pharmacology and Experimental Therapeutics. The study was funded by NIDA, the primary federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction. For more information about the study, contact the NIDA Press Office at (301) 443-6245.


For Immediate Release: May 10, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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NIDA-Funded Project-BEEMNET-Highlights Brain Awareness Week

The National Institute on Drug Abuse, National Institutes of Health, joins dozens of other Federal and private-sector sponsors in educational activities to mark Brain Awareness Week, May 12-18. Organized by the 25,000-member Society for Neuroscience, Brain Awareness Week will consist of more than 100 events across the United States, Canada, and Mexico to educate the public about the impact of neuroscience research on health and human potential.

Public lectures by leading neuroscientists will be offered throughout the week, and a number of North American universities will open their research facilities to afford the public a first-hand look at the research process. Project sponsors will also use interactive videos and the Internet to reach young minds during Brain Awareness Week.

The NIDA-funded BEEMNET (Brain Exchange Electronic Mentorship Network) is one unique project featured during Brain Awareness Week. BEEMNET uses the World Wide Web to link elementary school children and their teachers with research neuroscientists to better understand what neuroscientsts do and how their work furthers our understanding of learning, memory, and brain functioning and disorders. This linkage facilitates mentorships between the students, their teachers and neuroscientists. BEEMNET also displays stories and drawings of student impressions of a day in the life of a neuroscientist.

"It is both appropriate and promising that Brain Awareness Week will cast a spotlight on NIDA's work with young people," said Alan I. Leshner, Ph.D., Director of NIDA. "Projects such as BEEMNET reinforce our efforts to stimulate young minds and point them toward the field of neuroscience research," he added.

Developed through a Small Business Innovation Research grant with Dr. Deborah Colbern, BEEMNET is currently being used by elementary school students and their teachers at schools across the U.S. The BEEMNET site can be visited at http://www.beemnet.com/. During Brain Awareness Week, members of the press are invited to visit BEEMNET to receive an electronic press pass and virtual coffee and donuts.

NIDA is the Nation's lead agency for research on drug abuse and addiction. Further information about Brain Awareness Week, BEEMNET and other NIDA research initiatives is available through the NIDA Press Office, (301) 443-6245.


For Immediate Release: May 2, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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NIDA Seminar To Help With Drug Abuse Prevention In Communities Throughout Ohio

The National Institute on Drug Abuse, National Institutes of Health, and the Ohio Department of Alcohol and Drug Addiction Services (ODADAS) are sponsoring a one-day seminar, "Strengthening Communities Through Prevention: Applying Research to Policies and Programs." The event, scheduled for Thursday, May 9, at the Greater Columbus Convention Center in Columbus, Ohio, will focus on state-of-the art approaches to prevention of alcohol and other drug abuse.

"Strengthening Communities" will bring together local and state policymakers and professionals in the alcohol and drug abuse field to learn effective, community-based prevention strategies from eminent national researchers and experts. NIDA's Director, Alan I. Leshner, Ph.D., will speak on "What Research Has Taught Us About Drug Abuse and Addiction." Additional speakers will present key elements of drug abuse prevention, and model applications of drug abuse prevention programs.

"The seminar in Columbus offers a unique opportunity for Ohio legislators and program leaders to benefit directly from knowledge derived through NIDA-sponsored research," said Dr. Leshner. "It will help enhance everyone's ability—service providers, educators, civic organizations—to prevent drug abuse and addiction in their communities."

For further information or to register, contact the ODADAS Division of Prevention and Training, (614) 644-8326. Media organizations are asked to list the May 9 meeting in their events calendars. Media representatives are invited to attend and may register or set up interviews by contacting Mona Brown, NIDA Press Officer, at (301) 443-6245.


For Immediate Release: April 19, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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NIDA-ASAM Symposium Focuses on Treatment for Cocaine Addiction

The National Institute on Drug Abuse, National Institutes of Health, will co-sponsor, with the American Society of Addiction Medicine (ASAM), a one-day symposium, "New Medications for Treating Cocaine Abuse and Dependence: Bench to Bedside." The symposium, part of ASAM's 27th Annual Medical-Scientific Conference, is scheduled for Saturday, April 20, 8:30 a.m. - 5:45 p.m., at the Marriott Marquis in Atlanta, Georgia.

Several research directors from NIDA and experts in the field of addiction research will present findings on the neurobiology of cocaine addiction, the search for treatment medications, and integrated treatment approaches that combine cocaine treatment medications with behavioral interventions.

"Our knowledge about the neurobiology of cocaine addiction has increased significantly," says Alan I. Leshner, Ph.D., Director of NIDA. "This symposium provides a forum to disseminate new findings about cocaine addiction and their implications for treatment and medications development. It also provides a unique opportunity for a dialogue between practitioners, educators and researchers."

For more information on the symposium, call the NIDA Press Office at (301) 443-6245.


For Immediate Release: April 15, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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National Teleconference Highlights Drug Abuse Prevention Video

"Coming Together on Prevention," a video produced by the National Institute on Drug Abuse, National Institutes of Health, will be featured in a live, nationwide teleconference on Wednesday, April 17, from 2:00-3:30 p.m. Eastern Time. The interactive broadcast, "Pathways to Prevention," is designed to bring together more than 2,200 policymakers, community leaders, and prevention practitioners in a national forum on effective approaches to drug abuse prevention. Originating from KTBS-TV3 in Shreveport, LA, the program will be available through satellite downlink to more than 50 local sites around the country.

Dr. Alan I. Leshner, Director of NIDA said, "NIDA is pleased to share the results of its prevention research program and to promote effective approaches in preventing drug use among children and youth through this innovative dissemination mechanism."

NIDA's 27-minute video, "Coming Together on Prevention," presents three prevention models based on recent research: "Reconnecting Youth," aimed at high-risk students, "Strengthening Families," parenting skills for adults and drug-resistance skills for their children; and "Project STAR," a community-based program involving schools, parents, medial, local organizations, and public policy.

Two speakers, Mary Ann Pentz, Ph.D., and J. David Hawkins, Ph.D., will present their findings on effective prevention strategies and will participate in a roundtable discussion. Drs. Pentz and Hawkins have earned national recognition for their significant scientific contributions to the field of prevention research. An 800 telephone line will be available for live calls from satellite audiences.

Preventive action to help modify high-risk behaviors among children and youth is growing in importance. According to NIDA's Monitoring the Future Study of secondary school students, more young people are using drugs in their early teens, and students' attitudes reflect decreasing concern about hazards related to drug abuse.

Sponsors of "Pathways to Prevention" are the Satellite Wellness Action Network (SWAN), based in Shreveport, LA, and the Frost Foundation, Ltd. Technical assistance has been provided by NIDA.

The National Institute on Drug Abuse, part of the National Institutes of Health, is the primary Federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction. For more information on the satellite broadcast, contact SWAN at (318) 459-2435. For information on NIDA's prevention research program, call the NIDA Press Office at (301) 443-6245.


Embargoed for Release: Friday, March 15, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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NIDA Director To Discuss Behavioral Science Research in Drug Abuse

Alan I. Leshner, Ph.D., Director of the National Institute on Drug Abuse, National Institutes of Health, will present a keynote address, "Drug Abuse Is A Health Issue and Why Does It Matter?" to the Fourth International Congress of Behavioral Medicine in Washington D.C. Dr. Leshner will discuss the importance of drug abuse and addiction as a major avenue for increased morbidity and mortality of the nation.

Dr. Leshner will outline key issues for understanding and addressing the problems of drug abuse to more than 1,700 scientists and practitioners attending the Conference from around the world. "Research has taught us that drug abuse and addiction is not only a social issue, but also is a major health problem that dramatically affects both the health of individuals and the health of the public. To be effective, our strategies for dealing with drug abuse problems must continue to include a clear focus on the health aspects of drug abuse and addiction, and must include the public health solutions of education and prevention, treatment, and research," says Dr. Leshner.

In his address, Dr. Leshner will offer some provocative challenges for behavioral medicine researchers and practitioners highlighting the potential role of behavioral medicine in clarifying drug use as a personal health decision and a public health problem. He will also challenge behavioral scientists to look at ways to apply the techniques of behavioral medicine to the study of drug abuse.

Dr. Leshner will discuss NIDA's efforts to broaden basic behavioral science research in drug abuse. "We are interested in funding research proposals in the basic behavioral sciences which do not necessarily include the use of abused drugs in the research protocols but have clear potential for further study with drugs," says Dr. Leshner. Examples of research topics include: human and animal models of impulsivity and risk taking; the role of social attachment, social interactions, and social influence on high risk or deviant behavior; and behavioral factors leading to first use of drugs, and escalation to drug abuse and dependence.

The National Institute on Drug Abuse, part of the National Institutes of Health, is the primary Federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction. NIDA's Behavioral Sciences Research program is designed to bring the full range of social and psychological sciences to bear on the complex behavioral processes involved in drug abuse, thereby gaining access to new research tools and perspectives that will provide novel ways to approach drug abuse and addiction-related behaviors.

For additional information on NIDA's behavioral research program or other research supported by NIDA, contact the NIDA Press Office at (301) 443-6245.


Embargoed for Release: Thursday, March 14, 1996, 5:00 pm EST
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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Scientists Moving Closer To Identifying Compounds To Treat Cocaine Addiction

Researchers funded by the National Institute on Drug Abuse, National Institutes of Health, report important findings that have significant implications for the development of medications to treat cocaine addiction. Researchers at the Yale University School of Medicine in New Haven, CT have found that activation of the brain's D1 dopamine receptor system can suppress cocaine seeking in drug-experienced animals, whereas activation of the D2 dopamine receptor system can trigger cocaine seeking. This makes D1 receptor stimulation a potential target for the development of anti-cocaine addiction medications.

Alan I. Leshner, Ph.D., Director of NIDA, said, "These and other recent findings are finally enabling us to strategically develop effective medication treatments for cocaine addiction based on basic science. Because of the tremendous impact of cocaine addiction on the health of the public, NIDA has designated the development of a cocaine treatment medication as its top priority. This study helps move us forward in identifying target systems in the brain and in producing medications that would stop cocaine seeking behavior, interfere with and block craving, and prevent relapse to cocaine use after treatment."

The study, "Opposite Modulation of Cocaine-Seeking Behavior by D1- and D2-like Dopamine Receptor Agonists," was conducted by David W. Self, Ph.D., William J. Barnhart, B.A., David A. Lehman, B.A., and Eric J. Nestler, M.D., Ph.D. and is published in the March 15 issue of Science.

"Our work was based on the increasing knowledge of the molecular and cellular basis of cocaine addiction. This research illustrates how a strong foundation of basic neuroscience can facilitate the development of new and effective treatments for addictive disorders," said Dr. Nestler, the Elizabeth Mears and House Jameson Professor of Psychiatry and Pharmacology, and Director of the Division of Molecular Psychiatry, at the Yale University School of Medicine.

Activation of the brain's dopamine pathways is critically important to cocaine's effects. Dopamine, a chemical messenger in the brain, acts on nerve cells possessing specialized dopamine receptors, which are present in the brain in a variety of forms. Building on this knowledge of different types of receptors, the researchers tested the ability of compounds that selectively stimulate specific dopamine receptors to reinstate self-administration of cocaine in animals who had stopped seeking this drug. In this study, rats were allowed to self-administer intravenous cocaine for 2 hours and then saline was substituted for 2 hours during which time the self-administration behavior progressively diminished, a behavioral phenomenon known as extinction. The researchers found that when a D2-like agonist (a drug that mimics dopamine's effects on the D2 receptor) was administered to these animals, a dramatic increase in cocaine-seeking behavior was observed, while administration of a D1-like agonist had no effect.

Importantly, the researchers further tested whether the D1-like or D2-like agonists could block the effects of cocaine on reinitiation of cocaine use. In these rats, providing a small priming dose of cocaine causes an increase in cocaine-seeking behavior. While pretreatment with D2-like agonists in these animals caused dramatic potentiation of cocaine's priming effects, pretreatment with D1-like agonists completely prevented cocaine's ability to reinstate cocaine use. The research clearly shows that D1- and D2-like receptor agonists produce opposite effects, and suggests that D1-agonists might be useful in treatment of cocaine addiction.

"This study demonstrates an important dissociation between D1- and D2-like receptor mediated processes in cocaine-seeking behavior. We think that D1-like and D2-like dopamine receptors are involved in very different aspects of the addicting properties of cocaine. Whereas the D2-like receptor mediates the drive to take more cocaine, the D1-like receptor may affect some aspect of satiety or satisfaction," said Dr. Self, Assistant Professor of Psychiatry at Yale University.

Previous NIDA-funded research attempting to identify a medication for successful treatment of cocaine addiction has focused more heavily on dopamine receptor antagonists, which can block some of cocaine's acute reinforcing properties. However, these antagonists are associated with unpleasant and potentially serious side effects, particularly after repeated administration. They also have proven to be ineffective in numerous clinical trials. Other work has focused on D2-like agonists, but the present study raises the concern that such drugs could actually increase cocaine craving and aggravate the addiction.

The present research was conducted at the Connecticut Mental Health Center, a collaborative program of the State Department of Mental Health and Addiction Services and Yale University. Funding was provided by NIDA, the primary federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction. The development of new medications for treating drug addiction is a major part of NIDA's efforts.


For Immediate Release: Thursday, March 7, 1996
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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NIDA Broadens the Role of Neuroscience in Drug Abuse Research

Alan I. Leshner, Ph.D., Director of the National Institute on Drug Abuse, National Institutes of Health, announces in the current issue of NIDA NOTES that, "NIDA is expanding its neuroscience research program which since the 1970s, has revolutionized our understanding of drug abuse and addiction. Human neuroscience research offers great potential for further discoveries about the brain and addictive behaviors that we can apply to improving the effectiveness of drug abuse prevention and treatment."

In his Director's Column (page 3), Dr. Leshner discusses NIDA's new clinical neuroscience program which, he says, "will support biological and neurobiological assessments that attempt to determine which underlying factors make an individual more or less likely to become dependent on drugs."

The current NIDA NOTES summarizes a number of recent marijuana research and prevention activities, including:

"Marijuana Antagonist Reveals Evidence of THC Dependence in Rats," page 1
"NIDA Conference Advances HHS Secretary's Marijuana Initiative," page 5
"NIDA Expands Its Marijuana Research Agenda," page 5
"HHS Secretary Sends Marijuana Information to the Nation's Schools," page 6

Also in this current issue is a special report marking the 60th anniversary of NIDA's Addiction Research Center (ARC) and discussing ARC's current and future activities--researching all aspects of drug abuse and applying that knowledge to make drug abuse prevention and treatment more effective. The special 60th anniversary report includes:

"At 60, NIDA's Addiction Research Center Looks to the Future," SR-1
"History of ARC Marked by Research Achievements," SR2
"Using Animals to Study Mechanisms and Effects of Drugs," SR-3
"Molecular Pharmacology, Brain Scans, and Human Attention Spans, "SR-4
"Studying the Effects of Drugs in Humans," SR-6
"Developing New Therapies for Drug Abuse," SR-7
"Finding and Defining Causes of Drug Abuse," SR-8.

The National Institute on Drug Abuse, part of the National Institutes of Health, is the primary Federal agency conducting and supporting basic, clinical, and epidemiological research designed to increase knowledge and promote effective strategies to deal with the health problems and issues associated with drug abuse and addiction.

For more information about the stories in this issue of NIDA NOTES or about other research supported by NIDA, contact the NIDA Press Office at (301) 443-6245.


Embargoed for Release: February 20, 1996, 4:00 pm EST
Contact: Mona W. Brown or Sheryl Massaro: (301) 443-6245

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Attention and Memory Impaired in Heavy Users of Marijuana

A new study shows critical skills related to attention, memory, and learning are impaired among heavy users of marijuana, even after discontinuing its use for at least 24 hours. "This casts serious doubt on the common belief among many marijuana users that they are fine once the marijuana high wears off," says Alan I. Leshner, Ph.D., Director of the National Institute on Drug Abuse (NIDA), National Institutes of Health, which funded the study. "All along, we've been telling young people not to smoke marijuana, especially if they want to do well in school. Now we know that, for students who smoke marijuana heavily, the ability to learn is affected not just while they are high, but for at least a day after."

The study was conducted by Harrison G. Pope, Jr., M.D. and Deborah Yurgelun-Todd, Ph.D. at the McLean Hospital in Belmont, Massachusetts from 1991 to 1994 and is published in the February 21, 1996 issue of the Journal of the American Medical Association.

In the single-blind study of college undergraduate men and women, the researchers compared 65 "heavy users," who had smoked marijuana a median of 29 of the past 30 days, and 64 "light users," who had smoked a median of 1 of the past 30 days. Students were recruited based on self-reports of marijuana use during the past 2 years, as well as use of other illicit drugs and alcohol and tobacco. The study controlled for such traits as baseline intelligence levels, possible psychiatric disorders, family background, and use of other substances prior to the study period.

After a closely-monitored 19- to 24-hour period of abstinence from marijuana and other illicit drugs and alcohol, the undergraduates were given several standard tests measuring aspects of attention, memory, and learning, such as general intellectual functioning, abstraction ability, attention span, verbal fluency, and the ability to learn and recall new verbal and visual-spatial information.

The heavy users made more errors and had more difficulty in sustaining attention, shifting attention to meet the demands of changes in the environment, and in registering, processing, and using information (referred to as "executive cortical function") in comparison to the light users. Men in the heavy use group showed somewhat greater impairment than women in the same group. "The heavy users," says Dr. Pope, "could not pay attention to the material well enough to register the information in the first place so that it could be recalled and repeated later."

"We know from NIDA-funded research," says Dr. Leshner, "that daily marijuana use among young people has increased in recent years. Young people are putting themselves at high risk of failure due to their marijuana use."

The researchers suggest the finding of greater impairment among the heavy users is likely due to an alteration of brain activity produced by marijuana, a residue of the drug in the brain, or an actual drug withdrawal syndrome from marijuana. "We still do not know," says Dr. Pope, "whether certain effects of marijuana use are only short term or may also have much longer-term implications, even after all traces of marijuana have left the system." Continued research is planned to determine the neuropsychological function of long-term heavy marijuana users for up to 28 days after use is discontinued.

The National Institute on Drug Abuse, part of the National Institutes of Health, is the primary Federal agency responsible for basic, clinical, and applied research designed to improve and develop new strategies to deal with the health problems and issues associated with drug abuse and addiction.


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