Biomarkers As Intermediate Indicators of Improvement in ASD: A RCT with OMEGA-3

Background: A high ω6/ω3 ratio [fatty acid (FA) index] in the cell membrane has been associated with inadequate brain development. It has started to be used as a biomarker of treatment efficacy in human diseases.

Objectives: The aim of this study was i) to investigate if omega-3 supplementation improves erythrocyte membrane ω6/ω3, plasma antioxidant status (TAS) and autistic behaviors ii) to identify markers of response (i.e. baseline TAS, baseline ω6/ω3 ratio, age subgroups, etc.)

Methods: A randomized, crossover, placebo-controlled study was designed to investigate the effect of 8 weeks of supplementation with ω3 (962mg/d and 1155mg/d for children and adolescents, respectively). Sixty-eight children and adolescents with Autism Spectrum Disorders (ASD) completed the full protocol. Primary outcome measures were erythrocyte membrane FA composition and TAS. Secondary outcome measures were Social Responsiveness Scale and Clinical Global Impression-Severity.

Results: Treatment with ω3 improved the erythrocyte membrane ω6/ω3 ratio (treatment effect p<0.008, d=0.66; within subjects effect p<0.007, d=0.5) without changing TAS. There was a within subjects significant improvement in Social Motivation and Social Communication subscales scores, with a moderate to large effect size (p=0.004, d=0.73 and p=0.025, d=0.79 respectively), but no treatment effect (treatment-placebo order). Carryover effects cannot be discarded as responsible for the results in behavioral measures. When the sample was stratified into those with higher baseline antioxidant status and those with lower antioxidant status (<p50 vs p>50), the group with higher antioxidant status showed a greater benefit. In this group, there was a within-subject improvement in antioxidant capacity after supplementation with PUFAs (p<0.001, ηp2=0.247, large effect size); the ω3/ω6 ratio showed a treatment effect in both groups, as it does the whole sample (with a larger effect size in those with more baseline antioxidant stress (ηp2=0.194 vs ηp2=0.0.092). A further subdivision of the samples was conducted, with 2 groups, those with lower ω3/ω6 (percentile <50) (n=32) and those with higher ω3/ω6 (n=33). For the lower half of the sample, ω3/ω6 and AA/DHA showed a treatment effect (as did the whole group) (p=0.04 and p=0.02, respectively); a within-subjects effect was clear only in the lower ω3/ω6 group (p<0.001). All effect sizes were large. Further post-hoc analyses are being conducted in order to identify subgroups of patients that better respond to the intervention administered in this study.

Conclusions: In conclusion, supplementation with ω3 FA might be studied as an add-on to behavioral therapies in ASD. Optimal duration of treatment requires further investigation. With regard to side effects, the effect of this supplementation on the lipid profile needs monitoring.