Participant Characteristics
Participants ranged in age from 67 to 84 years with 44.7% aged 75 years and older. Mean scores on the 3MS at baseline and at each subsequent annual visit were: 94.5±4.1, 93.8±5.1, 93.1±5.7, and 93.2±6.3 for women, and 93.5±4.5, 91.9±6.1, 91.9±6.5, and 91.6±6.2 for men. On average, women scored higher than men on the 3MS at baseline (p < 0.001), were more likely to have hypertension (p = 0.003) and less likely to have diabetes (p < 0.001). No sex differences were found for age, education, or BMI. Participant demographic and health-related characteristics, including cognitive performance on the 3MS, for the total sample and stratified by sex are shown in Table 1.
[insert Table 1 on page 26]
Sex-specific Dietary Patterns
In men, two factors identified by PCA accounted for 5.8% and 5.1% of the total variance. The first pattern was characterized by high consumption of fruits, vegetables, fatty fish, legumes, nuts and seeds, rice and rice dishes, poultry, high-fiber cereals, tofu, and lower-fat dairy products, and was labelled the Prudent dietary pattern. The second dietary pattern was characterized by high consumption of red and processed meats, pork, potatoes, white bread, fried foods, butter, baked goods, sugary foods and drinks, high-fat dairy products, eggs and egg dishes, and salty snacks, and was termed the Western dietary pattern. A list of factor loadings for each food item are shown in Supplementary Table 1.
In women, two factors were identified by PCA, and accounted for 5.4% and 4.6% of the total variance. The first pattern, labelled the Prudent dietary pattern, was high in fruits, vegetables, fatty fish, poultry, rice and rice dishes, legumes, eggs and egg dishes, nuts and seeds, tofu, low-fat dairy products, and cheese. The second pattern, labelled the Western dietary pattern, was characterized by high consumption of red and processed meats, pork, white bread, potatoes, fried foods, butter, pasta, baked goods, sugary foods and drinks, high-fat dairy products, and salty snacks. Factor loadings for each food item are shown in Supplementary Table 2.
Dietary Pattern Adherence and Cognitive Function
Unadjusted linear mixed effects models revealed that, in men, higher adherence to the prudent dietary pattern was associated with better baseline cognitive performance (b = 0.534, p = 0.04); whereas greater adherence to the Western dietary patterns was associated with poorer baseline cognitive performance (b = -0.713, p = 0.005). In women, higher adherence to the prudent dietary pattern was also associated with better baseline cognitive performance (b = 0.654, p = 0.004), while the Western dietary pattern was not associated with baseline cognition (b = -0.368, p = 0.11).
Adjustment of the linear mixed effects models for covariates in men did not significantly change the association between Western dietary pattern adherence and baseline cognition (b = -0.652, p = 0.02); however, the association between prudent dietary pattern adherence and baseline cognition was no longer statistically significant following adjustment for covariates (b = 0.313, p = 0.22). In women, the association between prudent dietary pattern adherence and baseline cognitive function was no longer statistically significant following adjustment for covariates (b = 0.403, p = 0.12). Linear mixed effects models showed significant decline in 3MS performance over time in men (b = -0.63, p < 0.001) and women (b = -0.48, p < 0.001), which remained significant after controlling for covariates. However, unadjusted and adjusted models revealed that the slope of cognitive decline did not change as a function of degree of adherence to the prudent or Western dietary patterns in men and women (ps > 0.10). See Table 2 for all model details.
Table 2. Association Between Sex-specific Dietary Patterns, Baseline Cognition, and Cognitive Change Over 3 Years.
|
Unadjusted
|
Adjusted a
|
|
b
|
SE
|
p-value
|
b
|
SE
|
p-value
|
Women b
|
|
|
|
|
|
|
Time
|
-0.47
|
0.06
|
<0.001
|
-0.48
|
0.06
|
<0.001
|
Prudent Diet
|
0.65
|
0.23
|
0.004
|
0.40
|
0.26
|
0.12
|
Prudent Diet ´ Time
|
-0.05
|
0.06
|
0.35
|
-0.03
|
0.06
|
0.60
|
Western Diet
|
-0.36
|
0.23
|
0.11
|
-0.31
|
0.27
|
0.26
|
Western Diet ´ Time
|
-0.06
|
0.06
|
0.26
|
-0.08
|
0.06
|
0.16
|
Men
|
|
|
|
|
|
|
Time
|
-0.63
|
0.07
|
<0.001
|
-0.64
|
0.07
|
<0.001
|
Prudent Diet
|
0.53
|
0.26
|
0.04
|
0.31
|
0.26
|
0.22
|
Prudent Diet ´ Time
|
0.04
|
0.07
|
0.55
|
0.04
|
0.07
|
0.54
|
Western Diet
|
-0.71
|
0.25
|
0.005
|
-0.65
|
0.29
|
0.02
|
Western Diet ´ Time
|
-0.08
|
0.07
|
0.23
|
-0.08
|
0.07
|
0.21
|
Note. a Adjusted for age, education (<12, ³12 years), energy intake in kcal, BMI, diabetes, and hypertension; b Additionally adjusted for estrogen past or current estrogen use in women