Association Between Improved Serum Fatty Acid Profiles and Cognitive Function During a Dietary Intervention Trial in Relapsing-Remitting Multiple Sclerosis

Cognitive impairment is a common multiple sclerosis (MS)-related symptom that impacts quality of life (QOL). Diet interventions are shown to be beneficial in managing QOL, and the intake of essential fatty acids is linked with improved cognitive function. However, the effect of diets on serum fatty acid profiles and cognitive function is unknown. A previous randomized, parallel-arm trial recruited participants with relapsing-remitting MS (N = 77). Study visits included 4 time points: run-in, baseline, 12 weeks, and 24 weeks. During the run-in phase, participants followed their usual diet and were then randomly assigned to either a modified paleolithic (Wahls) or a low saturated fat (Swank) diet at baseline. Assessments at study visits included cognitive function assessed by Symbol Digit Modalities Test-Oral (SDMT-O) and Perceived Deficits Questionnaire (PDQ), and serum fatty acids, including eicosapentaenoic (EPA), docosahexaenoic (DHA), and arachidonic (ARA) acids. Both groups had significant improvements in all serum fatty acids ( < .01), except for ARA, as well as SDMT-O at 24-weeks ( < .05), total PDQ at 12 and 24 weeks ( < .01) compared with baseline values. The 12-week changes in ω-3 (EPA + DHA) index and EPA serum fatty acids were associated with SDMT-O changes ( ≤ .05); however, the changes in fatty acid levels did not mediate the effect of the diets on SDMT-O or PDQ ( > .05). Both diets led to improvements in serum fatty acid profiles and cognitive function, with associations between the 12-week ω-3 (EPA + DHA) index and EPA changes with SDMT-O.