Prenatal DHA supplementation and infant attention

Abstract

Background: Results of randomized trials on the effects of prenatal docosahexaenoic acid (DHA) on infant cognition are mixed, but most trials have used global standardized outcomes, which may not be sensitive to effects of DHA on specific cognitive domains.

Methods: Women were randomized to 600 mg/d DHA or a placebo for the last two trimesters of pregnancy. Infants of these mothers were then followed on tests of visual habituation at 4, 6, and 9 mo of age.

Results: DHA supplementation did not affect look duration or habituation parameters but infants of supplemented mothers maintained high levels of sustained attention (SA) across the first year; SA declined for the placebo group. The supplemented group also showed significantly reduced attrition on habituation tasks, especially at 6 and 9 mo.

Conclusion: The findings support with the suggestion that prenatal DHA may positively affect infants' attention and regulation of state.

Trial registration: ClinicalTrials.gov NCT00266825.

Figure 1

Infant HR during the various phases of habituation trials analyzed with mixed models. For ease of exposition, values are collapsed across multiple looks during the habituation session. Although the graph shows the well-documented and highly robust changes in HR with age over the first year and the deceleration seen during infant looking while in SA, there are no differences between Supplemented (solid line) and Placebo (dashed line) groups at any point during the trial. The top pair of solid/dashed lines are data from 4 month-olds, the middle pair are from 6-month-olds, and the bottom pair are from 9-month-olds. The downward-pointing arrow represents the onset of the stimulus; the box represents encapsulates the period during which infants were looking at the stimulus. HR = heart rate, SA = sustained attention, PreStim = prestimulus period (before onset of stimulus), OR = orienting, AT = attention termination, Postlook = postlook period (after look is terminated but before withdrawal of stimulus). Data points represent successfully completed habituation sessions where HR data could be successfully coded: n=159 (n=72 and n=87 placebo and supplemented, respectively) at 4 months, n=172 (n=71 and n=101) at 6 months, and n=156 (n=68 and n=88) at 9 mo.

Figure 2

Modeled data for proportion of time infants spent looking in SA as a function of randomized group assignment. Data are averaged across 4, 6, and 9 mo and reflect the significant Age X DHA Group interaction. Infants in the Placebo group (dashed line) showed a decrease in SA with age, infants in the Supplemented group (solid line) maintained levels of SA across the first year. Data shown are from completed habituation sessions where HR could be successfully coded: n=159 (n=72 and n=87 placebo and supplemented, respectively) at 4 months, n=172 (n=71 and n=101) at 6 months, and n=156 (n=68 and n=88) at 9 mo.

Figure 3

CONSORT diagram for follow-up of RCT on DHA prenatal supplementation. The attrition from delivery to the first-year tasks was 31.9% for the placebo group and 22.1% for the supplemented group.