The Long-Term Neurocognitive Consequences of Prenatal Alcohol Exposure: A 14-Year Study

Prenatal alcohol exposure, at doses not generally associ- ated with maternal alcohol problems, produces a broad array of neu- rocognitive deficits in offspring even in the absence of effects on growth and morphology. This report presents a summary of neuro- behavioral, growth, and morphology findings from long-term follow- up of a birth cohort of 500 from a population-based study that has revealed attention, memory, and information processing deficits from birth through 14 years. Also observed (from school age through 14 years) have been problems with antisocial and delinquent behaviors, and classroom learning and behaviors; some of these problems may be secondary to earlier neurocognitive disabilities. Continuing research in behavioral and neurobehavioral teratology provides important opportunities for the neurosciences and for improved health of future generations. In 1973, fetal alcohol syndrome (FAS) was identified as a birth defect presumed to be caused by prenatal alcohol exposure because the physical findings were observable at birth and the birth mothers of the first children so identified were chronic alcoholics (Jones & Smith, 1973). In the subsequent 25 years, alcohol has been irrefutably estab- lished as a teratogen through thousands of experimental animal stud- ies, the whole field of neurobehavioral teratology has emerged (Riley & Vorhees, 1986), and hundreds of studies have demonstrated the comparability of the neurobehavioral findings from human and animal research on the short- and long-term consequences of prenatal alcohol exposure (Table 1; Driscoll, Streissguth, & Riley, 1990). Although FAS has been identified as the most frequent known cause of mental retardation, clinical work proceeded slowly because of the subtleties of establishing the clinical diagnosis (Streissguth, 1997). FAS is diagnosed by the coexistence of three features: prena- tal-onset growth deficiency, a characteristic pattern of dysmorpholog- ical characteristics read most explicitly in the face, and evidence of central nervous system (CNS) dysfunction. But the diagnostic process has not been readily incorporated in clinical practice, and thousands of individuals remain undiagnosed. Hundreds of experimental animal studies have shown that the brain is the organ that is the most vulnerable to prenatal alcohol exposure (Goodlett & West, 1992) and that CNS effects can last a lifetime (Dumas & Rabe, 1994). However, no specific and unique clinical markers that are suitable for the detection of individuals with the CNS effects of prenatal alcohol exposure have emerged. The Institute of Medicine (Stratton, Howe, & Battaglia, 1996) recently suggested the new term alcohol-related neurodevelopmental disabilities (ARND) to describe children who were prenatally exposed to alcohol and have variable CNS effects but lack the physical features of FAS. Defining ARND poses a challenge for neuroscientists and clinicians that should not go unnoticed. The magnitude of the public-health problem posed by prenatal alcohol exposure is clear from two recent studies based on empirical and clinical methods. The first concluded that the incidence and preva- lence of FAS and ARND combined is almost 1 out of 100 live births (Sampson et al., 1997). The second documented the costly secondary disabilities, such as school or job difficulties, experienced by individ- uals with FAS and other fetal alcohol effects as they attempt to pursue lives handicapped by primary CNS disabilities that frequently go unrecognized (Streissguth, Barr, Kogan, & Bookstein, 1997). The present article describes findings from the Seattle Longitudi- nal Prospective Study (a population-based study ongoing since 1974) that demonstrate broad and variable CNS effects of prenatal alcohol in a primarily low-risk population conceived before general awareness of alcohol's adverse effects on pregnancy outcome and the later lives of children and adolescents. We propose using this accruing body of knowledge as a basis for developing tools that detect individuals affected by prenatal alcohol exposure, whatever their age. 1