Dietary quality may enhance survival related to cognitive impairment in Taiwanese elderly

BACKGROUND Impaired cognition increases mortality in the aged. It is unclear how dietary quality might affect this relationship. OBJECTIVE To examine how dietary diversity and cognition might interact to determine survival. DESIGN In a Nutrition and Health Survey in Taiwan (NAHSIT 1999-2000), 1,839 representative elderly were followed for mortality up to 10 years. The dietary quality measure was a dietary diversity score (DDS, range: 0-6) to present six food groups (dairy, meat, rice and grains, fruit, vegetable,fat and oil) derived from a 24-h dietary recall. Cognitive function was evaluated by the validated Short Portable Mental Status Questionnaire (SPMSQ). RESULTS Those with cognitive impairment (SPMSQ≥3 errors) had 2.56 (95% confidence intervals (CI), 1.99-3.28) times the all-cause-mortality risk of those with intact cognition. After control for potential confounders, the adjusted hazard ratio (HR) remained significant (1.46, 95% CI: 1.06-2.02). Significant interactions for DDS and cognition were found (p<0.001). Jointly, compared to normal-SPMSQ-highest DDS, the greatest HR is where impaired cognition is combined with the lowest DDS (HR 2.24, 95% CI: 1.19-4.24). Increased DDS was associated with improvement in survival that is especially evident in those with 1-2 errors where the greatest HR reduction was found, and for fruit. Attributability for mortality amounted to 18% for impaired cognition and 33% for least diverse diet. CONCLUSIONS Dietary diversity may improve survival in relation to impaired cognitive function.