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The
preface to Chapter 5, Prenatal Exposure to Alcohol from the
10th
Special Report to the U.S. Congress on Alcohol and Health, published by U.S. Department of
Health and Human Services, Public Health Service, National Institutes of
Health, and the National Institute on Alcohol Abuse and Alcoholism.
Fetal Alcohol Syndrome (FAS) is a set of birth defects caused by
maternal consumption of alcohol during pregnancy. At birth, children
with FAS can be recognized by growth deficiency and a characteristic set
of minor facial traits that tend to become more normal as the child
matures. Less evident at birth-but far more devastating to FAS children
and their families-are the lifelong effects of alcohol-induced damage to
the developing brain.
FAS is
considered the most common nonhereditary cause of mental retardation. In
addition to deficits in general intellectual functioning, individuals
with FAS often demonstrate difficulties with learning, memory,
attention, and problem solving as well as problems with mental health
and social interactions. Thus these individuals and their families face
persistent hardships in virtually every aspect of life.
Estimates
of FAS prevalence vary from 0.5 to 3 per 1,000 live births in most
populations, with much higher rates in some communities (Stratton et al.
1996). However, the diagnosis of FAS identifies only a relatively small
proportion of children affected by alcohol exposure before birth.
Children with significant prenatal alcohol exposure can lack the
characteristic facial defects and growth deficiency of FAS but still
have alcohol-induced mental impairments that are just as serious, if not
more so, than in children with FAS. The term "alcohol-related
neurodevelopmental disorder" (ARND) has been developed to describe
this condition. In addition, prenatally exposed children without FAS
facial features can have other alcohol-related physical abnormalities of
the skeleton and certain organ systems; these are known as
alcohol-related birth defects (ARBD).
Because
the effects of prenatal alcohol exposure on the developing brain appear
to be especially long lasting and debilitating, a significant proportion
of research has concentrated on brain malformations as well as cognitive
and behavioral abnormalities. In this chapter, the section on
"Prenatal Alcohol Exposure: Effects on Brain Structure and
Function" describes research using neuroimaging techniques to
provide precise pictures of brain abnormalities found in persons exposed
to alcohol before birth. The studies strongly support the notion that
alcohol has specific, rather than global, effects on the developing
brain. The section also describes current research on the many
behavioral manifestations of this structural brain damage, including
problems with cognitive and motor functions as well as mental health and
psychosocial behavior.
It is
unlikely that a single mechanism can explain all of the deleterious
effects that result from alcohol exposure during pregnancy. As described
in the section "Underlying Mechanisms of Alcohol-Induced Damage to
the Fetus," alcohol exerts its effects on the developing fetus
through multiple actions at different sites. In the developing brain,
for example, alcohol has been shown to interfere with the development,
function, migration, and survival of nerve cells. Also, in the embryonic
cell layer that develops into the bones and cartilage of the head and
face, alcohol exposure at critical stages of development induces
premature cell death that is thought to be linked to the FAS facial
defects. These actions of alcohol have provided scientists with numerous
paths for pursuing possible biochemical mechanisms for these actions.
Better understanding of the mechanisms may point to pharmacologic
approaches for intervening or for preventing alcohol-related fetal
injury.
Although
research in animals and humans is continuing to provide details about
alcohol-induced deficits, efforts to prevent these problems are not
nearly so advanced. The section "Issues in Fetal Alcohol Syndrome
Prevention" notes that numerous strategies to prevent FAS have been
implemented in recent years, but that rigorous analysis of the
effectiveness of these approaches is in its infancy. The section
summarizes major reviews of FAS prevention efforts, presents issues
related to research methods and evaluations, and describes research on
prevention approaches targeted to women at different levels of risk.
Recent research underscores an intensifying need for effective
prevention strategies. One study found that although alcohol use among
pregnant women decreased between 1988 and 1992 (from 22.5 to 9.5
percent), by 1995 it had increased to 15.3 percent (Ebrahim et al.
1998). Moreover, binge drinking (defined in the study as five or more
drinks per occasion) among pregnant women, a particularly hazardous
drinking pattern in terms of FAS risk, increased significantly between
1991 and 1995 (from 0.7 to 2.9 percent of pregnant women) (Ebrahim et
al. 1999). In light of these unsettling findings, and because FAS and
other adverse effects of drinking during pregnancy are completely
preventable, the need for a solid research base to guide prevention
program developers is critical.
References
Ebrahim, S.H.;
Diekman, S.T.; Floyd, L.; and Decoufle, P. Comparison of binge
drinking among pregnant and non pregnant women, United States,
1991-1995. Am J Obstet Gynecol 180(1 pt. 1):1-7, 1999.
Ebrahim, S.H.;
Luman, E.T.; Floyd, R.L.; Murphy, C.C.; Bennett, E.M.; and Boyle,
C.A. Alcohol consumption by pregnant women in the United States during
1988-1995. Obstet Gynecol 92(2):187-192, 1998.
Stratton,
K.; Howe, C.; and Battaglia, F., eds. Fetal Alcohol Syndrome: Diagnosis,
Epidemiology, Prevention, and Treatment. Washington, DC: National
Academy Press, 1996.
Read the full
report at the National Institute of Health website (This is a PDF file
and requires Adobe Reader):
10th
Special Report to the U.S. Congress on Alcohol and Health
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