Introduction:
With global population aging, identifying public health strategies to prevent or reduce cognitive decline is of increasing importance. This study explores the potential role of a modifiable dietary behavior, fish consumption, to reduce the rate of cognitive decline in a cohort of Chinese older adults.
Methods:
This study comprised adults aged ≥55 who completed a brief cognitive screening test at two or more waves of the China Health and Nutrition Survey (CHNS) from 1997 to 2004. The cognitive screening test had a maximum of 31 points and assessed immediate and delayed memory, attention, calculation, and orientation. Diet was measured by 3-day 24-hour recalls. Multivariable-adjusted linear mixed-effects models were used to evaluate the relation of fish intake at baseline with changes in cognitive scores, adjusting for age, gender, region, urbanization index, education, household income, energy intake, physical activity, current alcohol use, current smoking, and consumption of fresh vegetables, fruits, fresh legumes, and high-fat meat, as well as time, and time interactions with each covariate. Based on the distribution of fish intake, we compared consumption ≥1 vs. <1 serving/week. Sensitivity analysis included 1) removing shellfish and/or preserved fish; 2) exploring potential confounding by or interactions with hypertension or body mass index; 3) excluding those with the lowest 10% baseline cognitive scores; 4) adjusting for dietary patterns to determine if associations were independent of overall eating patterns; 5) using propensity score analysis to ensure comparability of the fish intake groups.
Results:
The average follow-up among 1566 older adults was 5.3 years, with a mean annual rate of decline 0.40 points. Since age significantly modified the fish-cognitive change association (p=0.003), we stratified analysis by adults <65 (n=968) at first measure, and ≥65 (n=598). No significant associations were found among adults <65. Among adults ≥65, compared with persons who consumed fish <1 serving/week, the average rate of global cognitive decline was reduced by 0.35 points per year or 55% (p = 0.001) among those consuming fish ≥1 serving/week. Results remained consistent in sensitivity analysis. When the cognitive test items were analyzed based on the domain assessed, fish intake was associated with a significantly slower rate of decline in memory scores among adults ≥65. The average rate of memory decline was reduced by 60% among persons who consumed fish ≥1 serving/week.
Conclusions:
Fish intake of at least 1 serving per week predicted a slower rate of cognitive decline among Chinese adults ≥65 years old, particularly for immediate and delayed memory. The cognitive benefits of fish intake were not apparent among Chinese adults aged 55 to 64. This is the first study in Chinese older adults to evaluate the role of fish consumption on cognitive decline.
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