What was the goal of your research or experiment?
Good cognitive health provides us with the ability to clearly think, learn and remember. These abilities are required to adequately perform daily activities. For elderly individuals, they are a major factor to ensure good quality of life and preserve independence. As the population ages, the increasing global prevalence of cognitive impairment, including dementia, is a growing public health concern. Faster rates of cognitive decline are likely to result in earlier onset of cognitive impairment and dementia. To date, there are still no effective treatments available to cure cognitive disorders or slow the rate of cognitive decline. Therefore, prevention strategies targeting modifiable risk factors, such as dietary intake and eating habits, are a promising approach.
Earlier research has suggested that milk and other types of dairy product consumption play a role in the prevention of age-related cognitive decline and dementia. However, evidence has been controversial and unclear, especially when it comes to changes over time and the impact of various types of dairy products, such as different types of milk based on its fat content as well as fermentation status of various dairy products, in relation to cognitive health.
In order to deepen the knowledge of this area, our research group conducted the present study to examine the impact of dairy intake, overall and based on different types of products, on 2-year changes in cognitive performance in older Spanish adults. These adults are part of the PREDIMED-Plus study, a large scale, longitudinal study on the effects of diet on health in Spanish elderly with high cardiovascular disease risk.
How did you measure or test this?
A total of 4,668 participants in the PREDIMED-Plus study, aged 55 to 75 years with overweight or obesity and with metabolic syndrome, completed a validated food frequency questionnaire at the start of the study. This questionnaire asked for the average consumption of milk and dairy products over the past year. Participants also took part in a comprehensive battery of neuropsychological tests, assessing various cognitive functions such as memory, attention, and executive function, among others. They did these tests at the start of the study, and again 2 years later.
What were the main results or findings?
We found that those participants who drank more milk (and whole-fat milk in particular) showed more cognitive decline (so worse performance after 2 years), compared to the other study participants who had lower intakes of milk. For other dairy products (i.e. lower fat milk, yoghurt, cheese) we found no associations with cognitive performance or decline.
What does this mean?
We found no clear evidence for prospective associations between dairy consumption and cognitive health in elderly. In addition, our findings suggest that there may be a relationship between whole-fat milk consumption and cognitive decline. More specifically, higher consumption of whole-fat milk may be associated with a greater rate of cognitive decline. However, due to the inherent characteristics of the present study (that is, an observational study), we cannot determine which factor is the cause and which factor is the effect. For instance, the participants who consumed more dairy products also differed from the other study participants in other ways: they were on average older, more often women, and more often had diabetes type 2, high cholesterol or symptoms of depression. Furthermore, we only studied older adults with overweight or obesity and with metabolic syndrome. We therefore cannot extrapolate these results to the general population, nor can we determine whether having a cardiovascular risk profile was a determining factor in these findings.
What is the next step?
Further prospective cohort studies and randomized clinical trials are required to confirm our results and to better understand the link between dairy product consumption and changes in cognitive performance. Ultimately, we aim to provide further evidence and specific nutritional and dietetic recommendations to support primary prevention, to inform cognitive health guidelines, and to eventually promote healthy cognitive aging.
Dairy Product Consumption and Changes in Cognitive Performance: Two-Year Analysis of the PREDIMED-Plus Cohort
Jiaqi Ni, Stephanie K. Nishi, Nancy Babio, Miguel A. Martínez-González, Dolores Corella, Olga Castañer, J. Alfredo Martínez, Ángel M. Alonso-Gómez, Enrique Gómez-Gracia, Jesús Vioque, Dora Romaguera, José López-Miranda, Ramon Estruch, Francisco J. Tinahones, José Lapetra, J. Luís Serra-Majem, Aurora Bueno-Cavanillas, Josep A. Tur, Vicente Martín-Sánchez, Xavier Pintó, José J. Gaforio, Ana Barabash Bustelo, Josep Vidal, Clotilde Vázquez, Lidia Daimiel, Emili Ros, Estefanía Toledo, Oscar Coltell, Carlos Gómez-Martínez, María Dolores Zomeño, Carolina Donat-Vargas, Leire Goicolea-Güemez, Cristina Bouzas, Manoli Garcia-de-la-Hera, Alice Chaplin, Antonio Garcia-Rios, Rosa Casas, Isabel Cornejo-Pareja, José Manuel Santos-Lozano, Teresa Rognoni, Carmen Saiz, Indira Paz-Graniel, Mireia Malcampo, Almudena Sánchez-Villegas, Itziar Salaverria-Lete, Ana García-Arellano, Helmut Schröder, Jordi Salas-Salvadó, PREDIMED-Plus investigators.
Molecular Nutrition and Food Research