Consumption of Dairy Products and Cognitive Functioning: Findings from the SU.VI.MAX 2 Study.
OBJECTIVES
Research concerning the link between dairy product intake and cognition is scant while experimental studies suggest links through various biological mechanisms. This study's objective was to examine the cross-time associations of total and specific dairy product consumption with cognitive performance in aging adults. We also explored compliance with dairy intake recommendations in France.


DESIGN
The study was based on the «Supplémentation en Vitamines et Minéraux Antioxydants» randomized trial (SU.VI.MAX, 1994-2002) and the SU.VI.MAX 2 observational follow-up study (2007-2009).


SETTING
A general-population cohort in France.


PARTICIPANTS
N=3,076 participants included in both the SU.VI.MAX and SU.VI.MAX 2 studies.


MEASUREMENTS
Dairy product consumption was estimated using repeated 24h records (1994-1996; mean=10 records, SD=3). Cognitive performance was assessed by neuropsychologists after an average of 13 years post-baseline via a battery of six validated tests. Mean age at the time of the cognitive function evaluation was 65.5 (SD=4.6) years. Principal component analysis revealed factors for verbal memory and working memory. Associations of energy-adjusted dairy product consumption and compliance with the respective dietary guidelines with subsequent cognitive impairment were examined using ANCOVA, providing mean differences (95% confidence intervals, CI) according to tertiles (T), adjusted for confounders including overall dietary patterns.


RESULTS
Total dairy product consumption was not associated with cognitive function. However, milk intake was negatively associated with verbal memory performance: mean difference T3 versus T1= -0.99 (-1.83, -0.15). Among women, consuming more than the recommended amount of dairy was negatively associated with working memory performance: excess versus adequate = -1.52 (-2.93, -0.11).


CONCLUSION
Our results indicate that dairy products consumption and especially compliance with dietary guidelines regarding dairy product intake are differentially associated with performance in specific cognitive domains after a comprehensive adjustment for lifestyle factors, health status markers and dietary patterns. Further longitudinal research is needed given the limited data available.