Adherence to a Mediterranean diet and cognitive function in the Age-Related Eye Disease Studies 1 & 2

Abstract

Introduction: The objective was to determine whether closer adherence to the alternative Mediterranean Diet (aMED) was associated with altered cognitive function.

Methods: Observational analyses of participants (n = 7,756) enrolled in two randomized trials of nutritional supplements for age-related macular degeneration: Age-Related Eye Disease Study (AREDS) and AREDS2.

Results: Odds ratios for cognitive impairment, in aMED tertile 3 (vs 1), were 0.36 (P = .0001) for Modified Mini-Mental State (<80) and 0.56 (P = .001) for composite score in AREDS, and 0.56 for Telephone Interview Cognitive Status-Modified (<30) and 0.48 for composite score (each P < .0001) in AREDS2. Fish intake was associated with higher cognitive function. In AREDS2, rate of cognitive decline over 5 to 10 years was not significantly different by aMED but was significantly slower (P = .019) with higher fish intake.

Discussion: Closer Mediterranean diet adherence was associated with lower risk of cognitive impairment but not slower decline in cognitive function. Apolipoprotein E (APOE) haplotype did not influence these relationships.

Trial registration: ClinicalTrials.gov NCT00345176.

Keywords: Mediterranean diet; age-related macular degeneration; cognitive function; fish consumption; genetic interaction.

FIGURE 1

Odds ratios for cognitive impairment and estimates of cognitive test score differences (with 95% confidence intervals) by tertiles of the modified Alternative Mediterranean Diet. Results are shown in comparison to tertile 1 (reference), following adjustment for baseline age, sex, race, smoking, diabetes, hypertension, baseline depression score (Center for Epidemiologic Studies Depression Scale [CES-D] ≥16 or not), total calorie intake, and (AREDS2 only) years from baseline. Significance was set (by Bonferroni correction) at P = .013

FIGURE 2

Participants with cognitive impairment (A) and estimates of cognitive test scores (B) from the Telephone Interview Cognitive Status-Modified, by tertiles of the modified Alternative Mediterranean Diet, in the Age-Related Eye Disease Study 2

FIGURE 3

Odds ratios for cognitive impairment and estimates of cognitive test score differences (with 95% confidence intervals) by quartiles of the individual components of the modified Alternative Mediterranean Diet. Results are shown in comparison to quartile 1 (reference), following adjustment for baseline age, sex, race, smoking, diabetes, hypertension, baseline depression score (Center for Epidemiologic Studies Depression Scale [CES-D] ≥16 or not), total calorie intake, and (AREDS2 only) years from baseline. For all components except alcohol, higher quartiles refer to higher levels of intake of the component. For alcohol (considered in binary fashion), group 2 (“in interval”) refers to intake within the specified interval (ie, adherent to the modified alternative Mediterranean diet), while group 1 (reference) refers to intake above or below the specified interval. For red meat, higher quartiles refer to higher levels of intake, which is less adherent to the modified alternative Mediterranean diet. For monounsaturated fatty acid:saturated fatty acid ratio (MUFA:SFA), higher quartiles refer to higher ratios of MUFA:SFA intake, which is more adherent to the modified alternative Mediterranean diet. Significance was set (by Bonferroni correction) at P = .0014