Introduction: Carbohydrate quality and quantity have been associated with several chronic diseases, but few studies have investigated associations with cognitive impairment. The objective of this study was to test the hypothesis that higher glycemic load (GL), glycemic index (GI), and available carbohydrate intakes are associated with higher odds of incident cognitive impairment in a large, prospective cohort.
Methods: This analysis utilized the REGARDS study, a national cohort of 30,239 black and white participants (age > 45 yr). Dietary intake was assessed by the Block98 food frequency questionnaire, from which values for GL, GI, and available carbohydrate (total carbohydrate minus dietary fiber) were estimated. Incident cognitive impairment was defined as shifting from an intact cognitive status (a score >4) at the first cognitive assessment to an impaired cognitive status (a score ≤4) at the most recent cognitive assessment, measured by the Six-Item Screener. Logistic regression was used to evaluate the odds of incident cognitive impairment by quintile of GL, GI, and available carbohydrate.
Results: This analysis included 16,755 participants free of stroke and cognitive impairment at baseline. A total of 1,513 cases of incident cognitive impairment were observed over a mean follow-up of 7.5 years. After adjustment for sociodemographic variables and cognitive risk factors, participants in the highest quintile of glycemic load had 42% higher odds of incident cognitive impairment compared to those in the lowest quintile (Q5 vs Q1: OR=1.42; 95% CI: 1.06, 1.89; p for trend: 0.02). Similarly, participants in the highest quintile of available carbohydrate had 42% higher odds of incident cognitive impairment (Q5 vs Q1: OR=1.42; 95% CI: 1.05, 1.91; p for trend: 0.04). No significant associations were observed with glycemic index (See Table 1).
Conclusion: Consuming a dietary pattern lower in available carbohydrate and glycemic load may aid in the preservation of cognitive function in older ages.