The prevalence of autism spectrum disorder (ASD) diagnosis is estimated to be 1% to 2% in the general population. Autism is characterized by a heterogeneous spectrum of neurodevelopmental conditions, marked by persistent difficulties in reciprocal social communication and restricted and repetitive behaviors and interests. In addition, these traits may manifest subclinically, known as the broader autism phenotype.
Prenatal dietary patterns have emerged as a potential factor in the onset of autism, although evidence is still limited. Previous studies have found that the use of prenatal multivitamin and folic acid supplements, adequate vitamin D status, and high prenatal fish intake are inversely associated with autism diagnosis and associated traits.
However, so far, only four studies have investigated this association with small sample sizes, which may increase the risk of errors and heterogeneous results. Therefore, this new work seeks to deepen this evidence by measuring the associations of high adherence to a healthy prenatal dietary pattern with autism diagnosis using data from two large prospective cohort studies: the Norwegian Mother, Father and Child Cohort Study (MoBa) and the Avon Longitudinal Study of South West England Parents and Children (ALSPAC).
Fewer communication problems in children at 3 and 8 years old
Participants included singleton pregnancies with self-reported responses to a food frequency questionnaire. MoBa recruited participants between 2002 and 2008, while ALSPAC recruited participants between 1990 and 1992, following children up to age 8 years or older. Recruitment rates were 41% in MoBa and 72% in ALSPAC. Data analysis was conducted between February 2022 and August 2023.
The study derived a healthy prenatal dietary pattern using factor analysis, modelling adherence as low, medium and high. In MoBa, outcomes were autism diagnosis and elevated scores on the Social Communication Questionnaire at 3 and 8 years, with additional analysis of subdomains of social communication difficulties and restrictive and repetitive behaviours. In ALSPAC, outcomes were elevated scores on the Social Communication Difficulties Checklist at 8 years. Final adjusted models showed that high adherence to a healthy dietary pattern was associated with reduced odds of autism diagnosis and social communication difficulties at 3 years in MoBa and at 8 years in ALSPAC, with no consistent evidence of association with other outcomes.
High adherence to a healthy prenatal dietary pattern (HPDP) was associated with a 22% reduction in the likelihood of autism diagnosis
In summary, in this cohort study of mother-child dyads, high adherence to a healthy prenatal dietary pattern (HPDP) was found to be associated with a 22% reduction in the likelihood of autism diagnosis. Regarding autism-associated traits, a relationship was found between social communication difficulties and higher adherence to the HPDP, although associations with restrictive and repetitive behaviors were inconsistent. In addition, it was noted that girls might have a higher association between adherence to the HPDP and social communication difficulties at age 8.
Despite these findings, causality of these associations cannot yet be confirmed. Further research is needed to corroborate these results, especially given the inconsistency in previous literature and in measures of autism-associated traits. The authors note that it would be beneficial to measure the subdomains both in combination and separately and to explore whether the associations vary by food group. Furthermore, triangulation with alternative study designs and exploration of potential mediators are necessary to support the causal interpretation of the associations observed in this study published in JAMA Network Open.
