Researchers at the Wayne State University School of Medicine have discovered that impaired eyeblink conditioning may help identify children who have been prenatally exposed to alcohol -- fetal alcohol spectrum disorder -- according to results published in the February 2008 issue of Alcoholism: Clinical & Experimental Research.

Sandra W. Jacobson, Ph.D., professor of Psychiatry and Behavioral Neurosciences at the School of Medicine, and a collaborative team of researchers from WSU, University of Delaware, University of Cape Town in South Africa, Stanford University and State University of New York, found that a deficit in eyeblink conditioning (EBC) can help identify children with probable fetal alcohol syndrome (FAS) and may also serve to identify alcohol-exposed children who lack distinctive FAS features.

Children with FAS have identifiable craniofacial abnormalities, and children with alcohol-related neurodevelopmental disorder can have significant cognitive impairments without facial anomalies. “Animal studies have shown that binge consumption of alcohol during pregnancy impairs EBC,” said Dr. Jacobson. “We wanted to see if we could use the EBC paradigm to identify underlying or subcortical deficits that are specifically affected by prenatal alcohol exposure in children.”

The Cape Coloured community in the Western Cape Province of South Africa has an extremely high incidence of FAS -- in fact, it is among highest in the world -- in this mixed–ancestry population. Historically, farm laborers were paid in part with wine, which is now outlawed. However, heavy alcohol consumption persists among some members of this community, including some pregnant women. Since 1998, Dr. Jacobson and her colleagues have been studying a group of women and their children, leading to this first prospective longitudinal study of children with FAS.

The researchers administered three sessions of 50 trials of eyeblink conditioning to 98 5-year-olds born to mixed-ancestry women in Cape Town, pairing a tone with an air puff. Normally after repeated pairing, a child as young as 5 months old will develop a conditioned eyeblink response.

“Even knowing the high incidence of FAS that has been documented in rural areas of the Western Cape province, we were surprised to see the very high incidence of children born with FAS and partial FAS (PFAS) in this urban mixed-ancestry cohort,” said Dr. Jacobson. “Twelve (18.8 percent) children born to the 64 heavy-drinking mothers met criterion for FAS, and an additional 18 (28.1 percent) for PFAS. Not a single child with FAS at this age met criterion for short-delay conditioning as contrasted with 75 percent of the controls. In addition, about two-thirds of the children with PFAS and two-thirds of the heavily exposed nonsyndromal children also did not meet criteria for conditioning. Given that we controlled for IQ and that EBC was not impaired in non-alcohol-exposed children with microcephaly, these findings suggest that the EBC deficit does not reflect impaired intellectual ability.”

Because infants reach functional capacity on EBC response by such an early age, infants at risk may be identified early in life. This assessment can also be used to help identify which nonsyndromal children are affected by the prenatal exposure.

“Our results show that there was a dose-response relation between alcohol exposure and FASD diagnosis and that a fundamental element of learning is affected by prenatal alcohol exposure,” said Dr. Jacobson. The team now plans to extend the study to examine EBC in 8- to 11-year-old mixed-ancestry children in Cape Town to see whether the findings at 5 years of age are also apparent in older children. The researchers hope to revisit the 5-year-old group that has been studied at 8.5 years to examine EBC and, in addition, assess EBC in infants to see how early this deficit can be detected.

The study was funded by the National Institute on Alcohol Abuse and Alcoholism, the National Institutes of Health Office of Research on Minority Health, the Foundation for Alcohol Related Research, Cape Town, South Africa and the Joseph Young Sr. Fund from the State of Michigan.