From an interview on Medscape (below), there was not a response in boys. Very odd.
"The lack of responsiveness of boys to the intervention is puzzling," the researchers write, "and the reasons are unclear."
"We can only speculate that there are differences in the metabolism of boys and girls that we do not yet understand," Dr. Makrides said during an interview. "The higher metabolic rate in boys may mean that they utilize much of the DHA they receive into energy. Also, boys may have a higher requirement for DHA. Clearly, this is an area of important research for the future."
The abstract is below and you can click on the title for the full study to read it for yourself
JAMA. 2009 Jan 14;301(2):175-82
Makrides M, Gibson RA, McPhee AJ, Collins CT, Davis PG, Doyle LW, Simmer K, Colditz PB, Morris S, Smithers LG, Willson K, Ryan P.
Child Nutrition Research Centre, Women's and Children's Health Research Institute, Women's and Children's Hospital, 72 King William Rd, North Adelaide SA 5006, Australia. email@example.com
CONTEXT: Uncertainty exists about the benefit of dietary docosahexaenoic acid (DHA) on the neurodevelopment of preterm infants.
OBJECTIVE: To determine the effect of meeting the estimated DHA requirement of preterm infants on neurodevelopment at 18 months' corrected age.
DESIGN, SETTING, AND PARTICIPANTS: Randomized, double-blind controlled trial enrolling infants born at less than 33 weeks' gestation from April 2001 to October 2005 at 5 Australian tertiary hospitals, with follow-up to 18 months.
INTERVENTION: High-DHA (approximately 1% total fatty acids) enteral feeds compared with standard DHA (approximately 0.3% total fatty acids) from day 2 to 4 of life until term corrected age. MAIN
OUTCOME MEASURES: Bayley Mental Development Index (MDI) at 18 months' corrected age. A priori subgroup analyses were conducted based on randomization strata (sex and birth weight < 1250 g vs > or = 1250 g).
RESULTS: Of the 657 infants enrolled, 93.5% completed the 18-month follow-up. Bayley MDI scores did not differ between the high- and standard-DHA groups (mean difference, 1.9; 95% confidence interval [CI], -1.0 to 4.7). The MDI among girls fed the high-DHA diet was higher than girls fed standard DHA in unadjusted and adjusted analyses (unadjusted mean difference, 4.7; 95% CI, 0.5-8.8; adjusted mean difference, 4.5; 95% CI, 0.5-8.5). The MDI among boys did not differ between groups. For infants born weighing less than 1250 g, the MDI in the high-DHA group was higher than with standard DHA in the unadjusted comparison (mean difference, 4.7; 95% CI, 0.2-9.2) but did not reach statistical significance following adjustment for gestational age, sex, maternal education, and birth order (mean difference, 3.8; 95% CI, -0.5 to 8.0). The MDI among infants born weighing at least 1250 g did not differ between groups.
CONCLUSION: A DHA dose of approximately 1% total fatty acids in early life did not increase MDI scores of preterm infants overall born earlier than 33 weeks but did improve the MDI scores of girls.