A November 2204 study examines the relationship between selected variables and prenatal alcohol exposure on subsequent IQ. Results indicate that maternal age and first-trimester drinking by mothers with a history of drinking problems can have substantial effects on IQ.
"FAS is characterized by growth retardation, central nervous system impairment, and a distinctive pattern of craniofacial anomalies," said Sandra W. Jacobson, a professor in the department of psychiatry and behavioral neurosciences at Wayne State University School of Medicine, and first author of the study. "ARND refers to nonsyndromal individuals with confirmed heavy prenatal alcohol exposure who exhibit measurable, but generally subtler neurobehavioral deficits than those seen with FAS.
"Whereas FAS is well established and easier to diagnose, it is not generally recognized that a child can be adversely affected by prenatal alcohol exposure without the characteristic facial features and growth deficits. Nonetheless, alcohol-exposed children with attention deficits or poor social judgment who lack the pattern of facial dysmorphic features may suffer from a similar set of problems that interfere with their academic and social performance."
Fetal Alcohol Exposure
"There is as of yet little public awareness or understanding of the behavioral teratologic sequelae of fetal alcohol exposure, such as the cognitive deficits found here in children who do not exhibit the physical markers of FAS," concurred Lynn T. Singer, Deputy Provost and Vice President for Academic Programs at Case Western Reserve University."This study is seminal in that it demonstrates that what was interpreted in prior studies as a lack of any IQ effects in nonsyndromal, alcohol-exposed children was really due to a differential effect of exposure related to several risk/protective factors studied by these researchers."
"The incidence and severity of FAS and ARND vary considerably among children with similar prenatal exposures," added Jacobson. "Despite extensive interest in the differential susceptibility attributed to influences ranging from genetic predisposition to nutritional inadequacy, there has been relatively little systematic empirical investigation of the factors that may determine which children are affected."
Substantial Effects on IQ
Researchers administered the Wechsler Intelligence Scales for Children-III (WISC-III) to 337 inner-city African American children at 7.5 years of age whose mothers were recruited prenatally. Alcohol exposure was assessed using a timeline, follow-back interview that was administered to the mothers at every prenatal clinic visit.Numerous potential confounding variables were examined, including maternal education and IQ, smoking and illicit drug use, quality of parenting, maternal depression and psychopathology, and current maternal drinking.
"This study is the first to demonstrate substantial effects on IQ among children with ARND born to older or MAST-positive mothers, particularly in relation to first trimester drinking," said Jacobson. "When we looked specifically at the children born to women 30 years or older, we found an alcohol effect on Full Scale IQ and five of the seven composite IQ scores. Similarly, we found IQ effects in children born to MAST-positive mothers.
Each Drink Lowers Baby's IQ
"For every two additional drinks consumed by the mother per day during pregnancy, we found a three-point decrease in Full Scale IQ and a five and a half point decrement on Freedom from Distractibility. These findings suggest that there are subgroups of more vulnerable and severely affected children with ARND, whose IQ scores and performance are compromised.""This study shows that the wide variability in child outcomes is related to the fact that some children are more susceptible than others to the effects of alcohol exposure, namely, those whose mothers are older than 30 years, those whose mothers have alcohol dependence, those whose parents provide a less stimulating environment, and those whose mothers reported drinking during the time of conception," said Singer, "In fact, for those children, even when they do not have FAS, there are strongly negative effects of alcohol exposure on verbal IQ and working memory, both important for learning and school success."
Both Jacobson and Singer noted that one very important implication of these findings is that a moderate-to-heavy drinking mother who has given birth to an unaffected child when she was younger needs to be warned that, if she drinks while pregnant, her risk of having an adversely affected child increases as she grows older.
