Red blood cell omega-3 fatty acid levels and neurocognitive performance in deployed US Servicemembers

Objective: To explore the cross-sectional relationships between blood eicosapentaenoic acid + docosahexaenoic acid (HSOmega-3 Index (R)) and sleep disorders, depression, anxiety, and neurocognitive performance in Servicemembers deployed to Iraq. Methods: Servicemembers with mild-to-moderate depression by the Patient Health Questionnarie-9 from two US military camps were invited to participate in this study. A battery of validated psychosocial (Pittsburgh Sleep Quality Index, and Zung Depression, Zung Anxiety, Epworth Sleepiness, and Combat Experiences scales) and computerized neurocognitive tests were completed by each participant. Five neurocognitive domain scores were calculated - Processing Speed, Complex Attention, Reaction Time, Cognitive Flexibility (CF), and Executive Function (EF). A drop of blood was also collected on an anti-oxidant-treated filter paper card and sent for HS-Omega-3 Index (R) analysis. An analysis of variance contrast was used to test for linear trends between quartiles of the HS-Omega-3 Index (R) for both EF and CF. Results: The mean HS-Omega-3 Index (R) was 3.5 +/- 0.7% (n = 78). The HS-Omega-3 Index (R) was not significantly associated with scores for anxiety, depression, or sleep, whether assessed as continuous or dichotomous variables, but was directly associated with CF and EF (P < 0.02 and 0.01, respectively), especially in the 81% who reported poor sleep quality. In those with poor sleep quality (n = 63), EF and CF were higher (P = 0.005) in subjects with Omega-3 levels above versus below the mean. Conclusion: Optimal neurocognitive performance is essential during deployment. Our finding that EF and CF were positively related to HS-Omega-3 Index (R) suggests that improving omega-3 status through an increase in omega-3 intake may improve neurocognitive performance and confer an element of resilience to poor sleep.