Villoz F, Filippini T, Blum M, Del Giovane C, Vinceti M, Rodondi N, Chocano-Bedoya P
5ÈME CONGRÈS DE PRINTEMPS SSMIG (19–21 MAI 2021)
Introduction: With aging population, prevention of cognitive decline is a major concern in primary care. Nutrition is a modifiable factor that could have a clinical impact in this prevention. In particular, the effects of the dairy intake on cognition are still controversial. We conducted a systematic review and meta-analysis on association between the dairy intake and cognitive decline or incidence of dementia with dose-response analysis.
Methods: We included longitudinal studies with community-dwelling adults ≥ 18 years unselected on the basis of chronic conditions. Our primary outcomes were the decline of cognitive function as defined in studies and incidence of dementia at end of follow-up. We identified relevant literature through a systematic search of Embase, Medline Ovid, Cochrane, Web of Science and Google Scholar from inception to end of July 2020. Two investigators conducted abstract and full-text screenings, data extractions, and risk-of-bias assessments using the Academy of Nutrition and Dietetics Quality Criteria Checklist (QCC). We performed a meta-analysis using a random-effects model.
Results: We included 11 prospective studies with 46,896 participants. We rated all studies at low risk of bias. Mean follow-up time was 11.7 years. Seven studies assessed cognitive decline through decrease in scores of various neuropsychological tests including MMSE (Mini-Mental State Examination). Three studies assessed dementia incidence using either MMSE threshold or DSM-IIIR/DSM-IV criteria. Comparing highest vs. lowest dairy intake, we found no association between dairy and cognitive decline. (Summary risk ratio-sRR=0.97; 95%CI 0.82, 1.16; 7 studies) although with large statistical heterogeneity (I2=76.75%). The dose-response analyses using g/day with 4 studies showed U-shaped curve, with lowest risk at approximately 120-130 g/day. We found an inverse association between the dairy intake and dementia incidence (sRR=0.61; 95%CI 0.44, 0.86; I2 =43.65%; 3 studies).
Conclusion: Our study suggests no association between the dairy intake and cognitive decline. However, the dose-response analyses infer a possible protective role, limited to a tight range of daily intakes. Moreover, we found that high dairy intake might decrease dementia incidence. Nevertheless, we should consider results with caution due to the heterogeneity of assessment. We need further studies to help guide patients with appropriate lifestyle recommendations to prevent cognitive decline.