We must stop the peasants from drinking! Popular summary below followed by Abstract. This is in most ways an unusually high-quality study. They actually made an attempt at community sampling and controlled for a few obvious things! Wow! Most unusual in the medical literature. But the heading on the journal article rightly shows an awareness that the causal inferences are still a problem.

The findings about attention deficit disorders are particularly interesting. What looks at first like an alcohol effect was shown on closer examination to be a family effect. Conduct problems generally, however, could not be ruled out as a family effect. This fits in with a view that attention-deficit syndrome is more strongly genetically determined than are conduct problems generally.

A major weakness of the study, however, is its reliance on maternal reports. This makes it particularly important that there was a failure to control for many possibly relevant psychological variables in the mother. To expect that there are not important psychological differences between mothers who drink daily and mothers who do not drink at all would be naive in the extreme — yet it seems primarily to be the difference between the children of those groups of mothers upon which the researchers hang their hat.

It could be asserted, for instance, that neurotic (or depressed, or introverted or abused or ….) mothers were both heavier drinkers and more likely to report problem behaviour in their children. In that case, the alcohol would NOT be the causal variable in the observed correlation. Only a study that used direct observation of behaviour could rule out such possibilities — though use of a comprehensive personality inventory would go some way towards alleviating doubts.

It may be worth noting that the conclusions below do not necessarily conflict with the recent study that found binge drinking to be harmless — as the study below focuses on chronic alcohol use. The contrast with the findings of the binge-drinking findings does however suggest that the generalizations permitted by the study below may be too crude to be useful. The question clearly now is HOW MUCH and WHEN drinking is harmful and the study below lacks the detail that would enable an answer to that

In the Archives of General Psychiatry this week, researchers report that women who drink alcohol during pregnancy increase the chances of their children having conduct problems. The study involved 4912 mothers and 8621 of their children. Mothers were surveyed about their substance use during each of their pregnancies, with average intakes ranging from zero to six standard drinks per day. Children were assessed every second year between ages 4 and 11 for behavioural problems.

For each additional day per week that mothers drank alcohol during pregnancy, their children showed a significant increase in conduct problems. And the findings held true even after accounting for other factors, including the mothers’ drug use during pregnancy, education level and intellectual ability.

Source

Causal Inferences Regarding Prenatal Alcohol Exposure and Childhood Externalizing Problems

By Brian M. D’Onofrio et al.

Context: Existing research on the neurobehavioral consequences of prenatal alcohol exposure (PAE) has not adequately accounted for genetic and environmental confounds.

Objective: To examine the association between PAE and offspring externalizing problems in a large representative sample of families in the United States using measured covariates and a quasi-experimental design to account for unmeasured genetic and environmental confounds.

Design: This study combines information from the National Longitudinal Survey of Youth and the Children of the National Longitudinal Survey of Youth. The analyses statistically controlled for measured characteristics of the mothers and families and exposure to other prenatal psychoactive substances. In the primary analyses, siblings differentially exposed to prenatal alcohol were compared.

Setting and Participants: Women were recruited from the community using a stratified and clustered probability sample and were followed longitudinally. The sample included 8621 offspring of 4912 mothers.

Main Outcome Measures: Maternal report of conduct problems (CPs) and attention/impulsivity problems (AIPs) during childhood (ages 4-11 years) using standardized assessments related to psychiatric diagnoses.

Results: There was an association between PAE and offspring CPs that was independent of confounded genetic and fixed environmental effects and the measured covariates. The CPs in children of mothers who drank daily during pregnancy were 0.35 SD greater than those in children whose mothers never drank during pregnancy. Although AIPs were associated with PAE when comparing unrelated offspring, children whose mothers drank more frequently during pregnancy did not have more AIPs than siblings who were less exposed to alcohol in utero. Additional subsample analyses suggested that maternal polysubstance use during pregnancy may account for the associations between PAE and AIPs.

Conclusion: These results are consistent with PAE exerting an environmentally mediated causal effect on childhood CPs, but the relation between PAE and AIPs is more likely to be caused by other factors correlated with maternal drinking during pregnancy.

Arch Gen Psychiatry. 2007;64(11):1296-1304

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