On Categorizations in Analyses of Alcohol Teratogenesis

Abstract

In biomedical scientific investigations, expositions of findings are conceptually simplest when they comprise comparisons of discrete groups of individuals or involve discrete features or characteristics of individuals. But the descriptive benefits of categorization become outweighed by their limitations in studies involving dose-response relationships, as in many teratogenic and environmental exposure studies. This article addresses a pair of categorization issues concerning the effects of prenatal alcohol exposure that have important public health consequences: the labeling of individuals as fetal alcohol syndrome (FAS) versus fetal alcohol effects (FAE) or alcoholrelated neurodevelopmental disorder (ARND), and the categorization of prenatal exposure dose by thresholds. We present data showing that patients with FAS and others with FAE do not have meaningfully different behavioral performance, standardized scores of IQ, arithmetic and adaptive behavior, or secondary disabilities. Similarly overlapping distributions on measures of executive functioning offer a basis for identifying alcohol-affected individuals in a manner that does not simply reflect IQ deficits. At the other end of the teratological continuum, we turn to the reporting of threshold effects in dose-response relationships. Here we illustrate the importance of multivariate analyses using data from the Seattle, Washington, longitudinal prospective study on alcohol and pregnancy. Relationships between many neurobehavioral outcomes and measures of prenatal alcohol exposure are monotone without threshold down to the lowest nonzero levels of exposure, a finding consistent with reports from animal studies. In sum, alcohol effects on the developing human brain appear to be a continuum without threshold when dose and behavioral effects are quantified appropriately.

Low–moderate prenatal alcohol exposure and risk to child behavioural development: a prospective cohort study

“…23 Further, the complexity of alcohol consumption over time in quantity and pattern makes it very difficult to speculate as to safe levels of alcohol consumption and this may have led authors to err on the side of caution. 4 Our finding that heavy alcohol consumption was not significantly associated with poorer behavioural outcomes was unexpected. We suggest that this finding was influenced by the small number of heavy drinkers in this cohort.…”

“…3 Many researchers have noted that most empirical enquiry into the effects of alcohol exposure during pregnancy has focused on and emphasised the devastating effects of high levels of alcohol exposure, often neglecting the influence of light-moderate drinking. 4 The studies that have examined the effects of low levels of exposure to alcohol and behavioural development have failed to reach consensus, perhaps in part due to a number of methodological limitations. 5 For example, the reliability of retrospective data collected up to 17 years postpregnancy has been questioned.…”

Exploring Mathematics Difficulties in Children With Fetal Alcohol Spectrum Disorders

“…Moreover, terminology for FASD-related conditions has changed drastically over the years, and thus researchers might use different terms to refer to similar samples of individuals. Although research indicates that the neuropsychologic deficits do not differ between those with and without the physical features of FAS (Mattson et al, 1998;Sampson, Streissguth, Bookstein, & Barr, 2000), future research using the same diagnostic approach and classifications would enable more reliable generalizations across studies. Furthermore, in many earlier studies, research participants were individuals with PAE but not necessarily with an FASD-related diagnosis.…”

Volume changes and brain‐behavior relationships in white matter and subcortical gray matter in children with prenatal alcohol exposure

“…Of the various cognitive domains affected in PAE, many studies have shown particularly poor arithmetic abilities [Goldschmidt et al, 1996;Streissguth et al, 1994], and performance has been linked to a dose-response relationship where higher PAE relates to poorer arithmetic scores [Sampson, Streissguth et al, 2000]. Additionally, those with PAE show many conduct and behavioral difficulties [Mattson, Crocker et al, 2011].…”