Omega-3 Fatty Acids, Prematurity, and Autism

Abstract

To the Editor.—I was interested to read about the high prevalence of autism in children born prematurely and weighing <1500 g.1 Birth weight had more effect than gestational age, indicating nutritional and/or placental function factors. Chorioamnionitis was a strong risk factor, which could be both a stress effect and a placental dysfunction effect. Stressful situations such as chorioamnionitis and placental hemorrhage cause β2 receptor simulation, which also occurs with agents used to stop premature labor, such as terbutaline. Such stimulation increases the risk for autism.2 It would be interesting to know the incidence of terbutaline use in this study.Another important potential cause of autism that would go along with low birth weight, prematurity, and placental dysfunction is deficient supply of omega-3 fatty acids (n-3 FAs) for a developing central nervous system. Males do not convert the α-linolenic acid (ALA) n-3 FA precursor to the longer docosahexanoic acid (DHA) as well as females, and females convert better during pregnancy.3 That may play a role in autism's male predominance. Increased risk among infants of older mothers4 may possibly be a result of decreased maternal conversion of ALA to DHA at older ages. DHA is present primarily in the retina and in the synaptic membranes of the cerebral cortex,5 where it is instrumental in membrane fluidity and function.6 There is continued buildup in the brain of n-3 FAs during gestation as well as through the first 2 years postnatally.5 Multiple births have to compete for a limited supply of these essential nutrients, thus explaining their higher autism risk. Premature infants, lacking the n-3 FA endowment they would have received had they gone to term, have shown the most benefit from n-3 FA supplementation.3 Regression, occurring in 30% of autistic children who were normally developing until the second year after birth,7 makes sense after a switch from breast milk or formula (containing ALA and DHA) to cow's milk, which has very few n-3 FAs.8 Comorbid conditions such as bipolar disease, attention deficit/hyperactivity disorder, and schizophrenia are found in 38% of autistic patients.2 Supplementation with n-3 FAs has been found to be helpful for each of these disorders.6,7 Modern diets deficient in essential nutrients such as n-3 FAs6 could explain the increase in diseases such as autism seen in the past 30 years.