Long-term Intake of Gluten and Cognitive Function among US Women

Importance: Gluten avoidance has been suggested as having a benefit to cognitive health among the general population, given the link between gluten and cognitive impairment in patients with celiac disease. However, data are lacking in individuals without celiac disease. Objective: To examine whether gluten intake is associated with cognitive function in women without celiac disease. Design, Setting, and Participants: This cohort study included US women who participated in the longitudinal, population-based Nurses' Health Study II and had not previously or subsequently been diagnosed with celiac disease. Dietary data were collected from 1991 to 2015, and data on cognitive function were collected from 2014 to 2019. Data analysis was conducted from October 2020 to April 2021. Exposures: Energy-adjusted gluten intake, cumulatively averaged across questionnaire cycles prior to cognitive assessment. Main Outcomes and Measures: Three standardized cognitive scores assessed by the validated Cogstate Brief Battery: (1) psychomotor speed and attention score, (2) learning and working memory score, and (3) global cognition score. Higher scores indicated better performance. Results: The cohort included 13494 women (mean [SD] age, 60.6 [4.6] years). The mean (SD) gluten intake was 6.3 (1.6) g/d. After controlling for demographic and lifestyle risk factors in linear regression, no significant differences in standardized cognitive scores (mean [SD], 0 [1]) by quintile of gluten intake were found across highest and lowest quintiles of gluten intake (psychomotor speed and attention: -0.02; 95% CI, -0.07 to 0.03; P for trend =.22; learning and working memory: 0.02; 95% CI, -0.03 to 0.07; P for trend =.30; global cognition: -0.002; 95% CI, -0.05 to 0.05; P for trend =.78). The null associations persisted after additional adjustment for major sources of dietary gluten (ie, refined grains or whole grains), comparing decile categories of gluten intake, using gluten intake updated at each previous questionnaire cycle, or modeling changes in gluten intake. Similarly, these associations were not materially altered in sensitivity analyses that excluded women who had reported cancer or dementia diagnosis or had not completed all dietary assessments. Conclusions and Relevance: In this study, long-term gluten intake was not associated with cognitive scores in middle-aged women without celiac disease. Our results do not support recommendations to restrict dietary gluten to maintain cognitive function in the absence of celiac disease or established gluten sensitivity.