Diet quality and cognition among older adults from the NuAge study

Background and objectives: A healthy diet may prevent cognitive decline either directly, or by decreasing risk of nutrition-related chronic diseases associated with cognitive decline. This study examined the relationships between diet quality (DQ) and cognition for over 3 years among 1488 older adults (52.6% female) from the NuAge study, aged 67 to 84 years at recruitment.

Methods: Cognition was assessed at four annual visits using the modified mini-mental status examination (3MS); rate of cognitive decline was computed for each participant over the 3 years of follow-up using mixed model analyses and the individual-specific number of months between 3MS assessments. Dietary data were collected at recruitment using a validated 78-item, semi-quantitative food frequency questionnaire (FFQ). DQ was characterized as the Canadian Healthy Eating Index (C-HEI), a 9-component global DQ index (maximum score=100) computed from the FFQ output. Other variables were collected by questionnaire or direct measurement. Multivariate analyses were carried out to assess the association of DQ controlled for confounders on cognition.

Results: Total C-HEI was better in females (78.7±9.1 vs 75.7±9.4, p<.0001) as were C-HEI component subscores. Males, the less educated, smokers, those with poor social engagement, symptoms of depression, a higher waist:hip ratio and who reported financial insecurity had a poor quality diet that could contribute to chronic diseases associated with cognition. Along with functional autonomy, most of these variables emerged as covariates of baseline 3MS and predictors of cognitive decline. While certain C-HEI subscores and total C-HEI were positive univariate correlates of 3MS at recruitment, total DQ was not associated with cognition in multivariate analyses, either at baseline or over 3 years of follow-up.

Conclusions: DQ was not independently associated with cognition. However, the study demonstrates relationships between diet quality and risk factors for chronic diseases associated with cognition. Consequently, older adults might benefit from a healthy diet to decrease risk of nutrition-related chronic diseases established as risk factors for cognitive decline. Further work in diverse older populations, use of dietary data collected earlier in life, finer cognitive measures and longer follow-up are necessary to better elucidate relationships between diet quality, chronic diseases and cognition.