Dietary fat types and 4-year cognitive change in community-dwelling older women

Abstract

Objective: A study was undertaken to relate dietary fat types to cognitive change in healthy community-based elders.

Methods: Among 6,183 older participants in the Women's Health Study, we related intake of major fatty acids (saturated [SFA], monounsaturated [MUFA], total polyunsaturated [PUFA], trans-unsaturated) to late-life cognitive trajectory. Serial cognitive testing, conducted over 4 years, began 5 years after dietary assessment. Primary outcomes were global cognition (averaging tests of general cognition, verbal memory, and semantic fluency) and verbal memory (averaging tests of recall). We used analyses of response profiles and logistic regression to estimate multivariate-adjusted differences in cognitive trajectory and risk of worst cognitive change (worst 10%) by fat intake.

Results: Higher SFA intake was associated with worse global cognitive (p for linear trend = 0.008) and verbal memory (p for linear trend = 0.01) trajectories. There was a higher risk of worst cognitive change, comparing highest versus lowest SFA quintiles; the multivariate-adjusted odds ratio (OR) with 95% confidence interval (CI) was 1.64 (1.04-2.58) for global cognition and 1.65 (1.04-2.61) for verbal memory. By contrast, higher MUFA intake was related to better global cognitive (p for linear trend < 0.001) and verbal memory (p for linear trend = 0.009) trajectories, and lower OR (95% CI) of worst cognitive change in global cognition (0.52 [0.31-0.88]) and verbal memory (0.56 [0.34-0.94]). Total fat, PUFA, and trans-fat intakes were not associated with cognitive trajectory.

Interpretation: Higher SFA intake was associated with worse global cognitive and verbal memory trajectories, whereas higher MUFA intake was related to better trajectories. Thus, different consumption levels of the major specific fat types, rather than total fat intake itself, appeared to influence cognitive aging.

Figure 1. Multivariable-adjusted Least-squares Means Global Cognitive* Scores over 4 years, by Quintiles of Fat Types (n=6,172)^†

* Global score combines results of the TICS (Telephone Interview for Cognitive Status), category fluency, immediate and delayed recall trials of East Boston Memory Test (EBMT), and delayed recall trial of the TICS 10-word list; verbal memory score combines results of the immediate and delayed recall trials of EBMT and the TICS 10-word list; mean (SD) span between the 1^st and 3^rd assessments was 4.0 (0.3) years. Adjusted least-squares means were obtained from the repeated measures analysis models involving N=6,172 participants. ^† SFA = saturated fatty acid; MUFA = mono-unsaturated fatty acid; PUFA = poly-unsaturated fatty acid; Trans = trans fatty acid; Q1 = lowest quintile of intake; Q5 = highest quintile of intake; models adjusted for mean-centered age at initial cognitive assessment (continuous, in years), educational attainment (bachelor’s degree or above versus associate’s degree), race (white/non-white), annual household income (≥$50,000/less), randomized treatment assignment (aspirin, vitamin E), other fat intake, protein intake, total energy intake, body mass index (<25, 25.0–29.9, or ≥30 kg/m²), current cigarette smoking (yes/no), postmenopausal hormone use (ever/never), history of hypertension (yes/no), history of elevated cholesterol (yes/no), history of depression (yes/no), history of diabetes (yes/no), daily alcohol consumption (yes/no), exercise (≥1 times per week/less), and all covariate-by-time interactions. P-values are from the Wald tests of interactions between fat type consumption level (medians-per-quintile) and time. N.B.: N=11 women were missing data at initial cognitive testing on components tests required to compute the global score.

Figure 2. Multivariable-adjusted Least-squares Means Verbal Memory* Scores over 4 years, by Quintiles of Fat Types (n=6,176)^†

* Global score combines results of the TICS (Telephone Interview for Cognitive Status), category fluency, immediate and delayed recall trials of East Boston Memory Test (EBMT), and delayed recall trial of the TICS 10-word list; verbal memory score combines results of the immediate and delayed recall trials of EBMT and the TICS 10-word list; mean (SD) span between the 1^st and 3^rd assessments was 4.0 (0.3) years. Adjusted least-squares means were obtained from the repeated measures analysis models involving N=6,176 participants. ^† SFA = saturated fatty acid; MUFA = mono-unsaturated fatty acid; PUFA = poly-unsaturated fatty acid; Trans = trans fatty acid; Q1 = lowest quintile of intake; Q5 = highest quintile of intake; models adjusted for mean-centered age at initial cognitive assessment (continuous, in years), educational attainment (bachelor’s degree or above versus associate’s degree), race (white/non-white), annual household income (≥$50,000/less), randomized treatment assignment (aspirin, vitamin E), other fat intake, protein intake, total energy intake, body mass index (<25, 25.0–29.9, or ≥30 kg/m²), current cigarette smoking (yes/no), postmenopausal hormone use (ever/never), history of hypertension (yes/no), history of elevated cholesterol (yes/no), history of depression (yes/no), history of diabetes (yes/no), daily alcohol consumption (yes/no), exercise (≥1 times per week/less), and all covariate-by-time interactions. P-values are from the Wald tests of interactions between fat type consumption level (medians-per-quintile) and time. N.B.: N=7 women were missing data at initial cognitive testing on components tests required to compute the verbal memory composite.