Alan I. Leshner, Ph.D.
National Institute on Drug Abuse
National Institutes of Health
Department of Health and Human Services
October 29, 1997
Statement for the Record
Mr. Chairman and Members of the Subcommittee, I am pleased to be here with my distinguished colleagues to discuss current research findings and future research directions on a topic of tremendous importance to every person in this country -- the health of our children. It may not be immediately clear to some people why the Director of the National Institute on Drug Abuse (NIDA) is testifying on the topic of children's health, since they see drug abuse and addiction as really adult problems. But, as many lines of research are now showing, drug use and addiction are as much children's issues as they are adult issues. Drug use is beginning at an earlier and earlier age, drug use has continued to increase among youth at all ages, and children are being affected by drugs in a variety of harmful ways. For these reasons, NIDA has made children and adolescents one of its highest priority areas, and is dedicating a large portion of its research portfolio to the study of the effects that drug abuse and addiction have on infants, children and adolescents.
Drugs can have a significant impact on the health of children in three significant ways: Exposure through maternal use during pregnancy, by growing up in a household where drugs are abused, or by abusing drugs themselves. NIDA's research portfolio addresses all of these issues, including the study of the consequences of prenatal drug exposure, etiology and epidemiology of drug use, drug abuse prevention, treatment of drug abuse and addiction, and drug abuse aspects of child and adolescent HIV/AIDS.
Before I highlight some of our major research findings in each of these areas and identify some of our future research directions, I need to acknowledge the breadth of knowledge that is still needed to fully understand this complex subject. As I travel around the country disseminating our research findings to a wide variety of audiences, I am both pleased and dismayed by the thoughtful questions I receive, since there are many important subjects about which we really know very little. For example, during a Town Meeting in San Francisco, a law enforcement officer, concerned about increased methamphetamine use in eighth grade students asked, " Is there a difference in the effects of drug use on the brain of an 11 year-old compared to say a 17-year-old?" That is an excellent question and one that I wish I could have answered. But the truth is we do not know the answer--yet. We are now beginning to address a whole range of questions that have never even been asked before. Let me begin by highlighting what we do know:
NIDA estimates that about 5.5 percent, or 221,000 women, used an illicit drug at least once during pregnancy, and thus 221,000 babies were born drug exposed. Cocaine was used during pregnancy by 1.1 percent or 45,000 women. And we have learned that virtually any exposure is dangerous.
Babies born to mothers who abused drugs during pregnancy often are prematurely delivered, have low birth weights, smaller head circumferences, and are often shorter in length. Estimating the full extent of the consequences of maternal drug abuse is more difficult, and determining the specific hazard of a particular drug to the unborn child is even more problematic given that most drug users use more than one substance. Factors such as the amount and number of all drugs used, inadequate prenatal care, socio-economic status, poor maternal nutrition, other health problems, and exposure to sexually transmitted diseases are just some examples of why it is difficult to determine the exact effects of prenatal drug exposure. Sorting out these confounding factors is extremely difficult. This is one of the reasons why we must be cautious in drawing causal relationships in this area, especially with a drug like cocaine.
"Cocaine: Effects on the Developing Brain" is the title of a very important meeting that was just held in mid-September by the New York Academy of Sciences and sponsored in part by NIDA. This landmark conference brought together, for the first time ever, all the major basic and clinical researchers to discuss what they know and what they do not know. The findings discussed at this meeting may account for the recent flurry of media attention on a subject that captured the public's concern and imagination back in the mid eighties. "Crack babies" or babies born to mothers who used cocaine while pregnant were written off as a lost generation by many people a decade ago. They were predicted to suffer from severe, irreversible damage, including reduced intelligence and social skills. And, of course, we now know this was a gross exaggeration. Most crack-exposed babies appear to recover quite well. However, the fact that most of these children appear quite normal should not be over-interpreted as a positive sign. As we continue to study prenatal cocaine exposure effects on later behavior, as cohorts of crack-exposed babies are now entering elementary school and middle school, we are finding that some, though not all, children in fact may be significantly, although perhaps subtly, affected by prenatal cocaine exposure.
Under the leadership of our colleagues from the National Institute of Child Health and Human Development (NICHD), and with the Administration for Children, Youth and Families (ACYF) and the Center for Substance Abuse Treatment (CSAT) we co-sponsored the Maternal Lifestyles Study (MLS) that has been examining the health and developmental sequelae of infants and children exposed to illicit drugs during pregnancy. The MLS which began in 1991 is following a sample of 1400 infants. Data are being collected at 9 assessment points between 1 month and 3 years of age. A follow-up study is also underway to follow these children into their school years when problems of learning disabilities, hyperactivity, and emotional disorders tend to emerge.
The MLS is one of several NIDA-supported studies that will continue to follow a large number of drug exposed children through their school years. Researchers who have been studying many of these children since birth are looking not only at the child's intellectual status, but at their behavioral, emotional and social development as well. Using sophisticated technologies, scientists are finding that exposure to cocaine during fetal development may lead to subtle, but significant deficits later on, especially with behaviors that are crucial to success in the classroom, such as blocking out distractions and concentrating for long periods of time.
For example, researchers at Yale University who have been following a group of nearly 500 children for six years have found that many cocaine-exposed, four-and-a-half year olds are more impulsive and more easily distracted than their peers. And other studies are showing subtle cognitive and learning problems in some prenatally cocaine-exposed children appearing as they enter middle school. Because these effects can be subtle and only expressed as children develop, long-term follow-up is needed. Long term or longitudinal studies will also enable us to examine whether prenatally drug-exposed children are themselves more vulnerable, or at increased risk for drug abuse in childhood and adolescence.
In addition to monitoring the development of children through their infancy and early school years to learn about the effects of prenatal cocaine exposure, research in this area also relies heavily on animal models. In fact, a recent discovery may now help explain some of the problems observed in humans who are exposed to cocaine during pregnancy--such as the subtle behavioral and cognitive effects that may appear in later development. And those animal studies are providing important hints as to the mechanisms by which prenatal drug exposure can affect later behavior. As one example, many people have believed that most prenatal drug effects result from the effects of drugs on the mother's circulatory system, thus altering the amount of blood or oxygen circulating to the fetus. However, a recently published study at the University of Massachusetts has demonstrated the presence of cocaine receptors in the brains of fetal rats and showed that cocaine is able to bind directly to these brain sites, which could, then, be another mechanism to modify brain development and later behavior, by modifying brain activity directly. With this new information about cocaine receptors in fetal brain tissue, researchers may be able to pinpoint the specific sites in the developing brain that are most vulnerable to cocaine and develop better prevention and treatment strategies.
Another aspect of drug abuse and addiction that may affect the overall health of a child is the environment in which he or she is brought up. Families play a crucial role in human development throughout the life-span. Research has demonstrated that parenting styles, parenting behaviors, parental substance use, the quality of the parent-child relationship and the family environment all contribute to the acquisition and development of both adaptive and maladaptive behaviors in children and adolescents. The parent-child relationship has been identified as a crucial determinant of adolescent drug use. A variety of NIDA-supported studies, including a major research center at the University of Miami, are dedicated, first, to understanding the role of early family environments in determining later drug use, and, second, to determining what kinds of family-based interventions, like strengthening parenting skills, can be used to offset these early affects.
NIDA research also examines the correlation between drug abuse and family violence. Research on this important subject is concentrated in three areas: The role of child abuse and neglect in the development of drug abuse; the role of drug abuse in the perpetration of child abuse, neglect and family violence; and most importantly, the development of intervention strategies to prevent child abuse and neglect and violence associated with drug abuse.
There is a whole series of issues surrounding initial drug use, and our concern that younger and younger children are using drugs. There is no single factor that determines whether a person might abuse a drug; instead drug abuse develops from the interaction of complex biological, behavioral, and social/environmental determinants. Researchers have identified many of the risk factors that are typically associated with those who develop drug abuse problems, including as I earlier emphasized, lack of stable family environments, and issues in the community, such as peer influences, and drug availability. Although these risk factors are not necessarily predictive for a particular individual, they are useful in defining levels of risk for initial drug use.
Researchers have also identified many of the protective or resilience factors, such as parental involvement in the life of a child, that typically reduce the chance of even those children with many risk factors from actually becoming a drug abuser. We will continue to rely on research to understand the biological, psychological, and environmental factors and their interactions involved in a person's first use of drugs and the risk for subsequent progression to addiction. As just one example, a group of studies is looking at the roles that decision-making processes and peer pressure have on a child's susceptibility to drug-taking behaviors. As another example, studies are examining how specific risk factors, like unstable family environments, can be offset by increasing the impact of protective factors like surrogate parenting, or mentoring programs.
By combining advances in understanding both risk and protective factors, we are now able to develop more effective drug use prevention strategies. We view prevention in two contexts: (a) prevention of initial drug use and (b) prevention of the health consequences of drug use for the individual, his or her offspring, and society.
Much has been learned about drug abuse prevention. Over a decade of research has made clear, for example, that community-wide coalitions working on comprehensive prevention programs that involve the family, schools, communities and the media in delivering consistent and persistent anti-drug messages can be quite effective in reducing drug abuse. Moreover, NIDA-supported studies are emphasizing that working with the entire family is much more effective in reducing the risks of drug abuse than working with the parents or the children alone. In fact, family intervention programs that intervene in early childhood to improve family functioning and parenting skills could reduce risk factors and build resistance to drug use even before the children enter school, thereby making them less vulnerable to environmental influences.
Also in the prevention area, we are supporting research on the special needs of older children and adolescents who have dropped out of school, run away from home, have become homeless, or have been placed in juvenile court detention programs.
As many of our Nation's best monitoring tools, such as the longtime NIDA supported Monitoring the Future Study, continue to find that drug use has been increasing among our youth and that children are beginning drug use at ever earlier ages, the more hopeful side of the story is that research is better informing how we can reverse these trends. And we are working hard to make sure that these science-based principles of prevention will be used in real-life prevention programming.
There are two new products of which I am particularly proud. One is "Preventing Drug Use Among Children and Adolescents." This easy to read brochure is the first ever research-based prevention guide that a school or community can use to implement a prevention program that is specifically tailored to meet their own community's particular needs. The user-friendly guide summarizes knowledge gleaned from over 20 years of research and provides practical guidance on how the 14 identified prevention principles can be applied by a community to address local drug abuse problems. The public response to the guide has been tremendous, resulting in the distribution of an initial 100,000 copies to schools and communities across the country, with additional requests averaging about 20,000 per month. Now that this tool has been developed and disseminated, NIDA will work with local communities to ensure effective prevention programs can be implemented at the community level. We also plan to work with the communities to evaluate the effectiveness of these programs.
The second set of materials is the colorful new "Mind Over Matter" series that I just unveiled two weeks ago at the Annual Meeting of the National Association of Biology Teachers in Minnesota. Mind Over Matter is a series of drug education brochures for students in grades five through nine to spark their curiosity and to inform them with scientific research findings on the brain effects of drug abuse. These six colorful, oversized, glossy magazines that unfold into posters explore the effects drugs have on the brain and also help encourage student interest in neuroscience. The Mind Over Matter magazine-posters explain the effects marijuana, opiates, inhalants, anabolic steroids, stimulants, and hallucinogens have on the brain. The series also includes a comprehensive teacher's guide with suggested activities to encourage students in scientific discovery, since one of the prevention principles articulated in our prevention guide is that simple didactic approaches, or lecturing young people, are ineffective; we need to foster other approaches to engage students to think about and discuss drug-related issues.
NIDA is also supporting research in the important area of treatment of drug abuse among adolescents. These investigations address a number of topics, including (a) mental health comorbidity and treatment implications, (b) screening and diagnostic assessment for use in matching each youth to the most appropriate available treatment, c) the development or modification of treatment modalities (e.g., family-based therapy, therapeutic community), (d) treatment service utilization, (e) treatment program evaluation, and (f) aftercare programming.
All of these accomplishments and activities are parts of what we are calling NIDA's Children and Adolescents Research Initiative, with prevention as the cornerstone. The outcomes will include much better understanding of the roles of risk and protective factors, and what to do about and with them. They also will include the development of improved, targeted treatment approaches sensitive to the unique needs of youth, especially treatments that are geared toward younger adolescents and pre-adolescents. NIDA will also conduct additional research to prevent or diminish the health and developmental consequences associated with drug abuse and addiction. Both animal and human models will also be expanded to clarify the differential effects of drugs on the brain and behavior of children at different ages.
We are very encouraged that some basic, but extremely important questions, such as "what works in prevention" have been at least partly answered and that this information is now being disseminated to communities. There remain unanswered, however, numerous questions about how to move from the general principles of prevention to exactly how to apply them in various real life settings. And there are many unanswered questions about how drug abuse and addiction affect our children. It has only been within the last few years that our understanding of basic neurobiology has matured enough, and only with the emergence of new non-invasive technologies have we become able to intensively study the underlying biological responses of humans to various drugs of abuse. To the extent that there are differences in children, adolescents and adults, this new knowledge will provide the infrastructure in which to identify those differences, and to develop appropriate prevention and treatment strategies so that our children can live healthy, productive, and drug-free lives.
Thank you, Mr. Chairman. I will be pleased to respond to any questions the Subcommittee may have.