Mediterranean Diet Improves Weight but Lacks Cognitive Benefits in Aging Adults

In a recent study published in the journal *Preventive Medicine Reports*, researchers conducted a 14-month randomized trial to explore the impact of the Mediterranean diet on cognitive and cardiometabolic health in older African American adults with obesity. The trial, known as the Building Research in Diet and Cognition (BRIDGE) study, enrolled 185 participants aged 55 to 85, primarily African American, with a Body Mass Index (BMI) ranging from 30 to 50 kg/m². The findings reveal that while the Mediterranean diet significantly improved dietary quality and reduced body weight and visceral fat, it did not yield any cognitive enhancements compared to usual dietary habits.

The BRIDGE study aimed to address the notable lack of rigorous evidence regarding dietary interventions for cognitive health, particularly among African American populations who experience disproportionate rates of dementia and obesity. According to Dr. Andrew McLeod, a principal investigator and researcher at the University of Chicago, "This study is particularly significant as it focuses on a demographic that has been historically underrepresented in dietary research."

During the eight-month active intervention phase, participants were divided into three groups: one following the Mediterranean diet with weight loss (MedWL), another following the Mediterranean diet alone (MedA), and a control group. All participants attended weekly classes focused on Mediterranean cooking and dietary principles. The MedWL group aimed for a weight loss of 5-7%, which was successfully achieved, with an average weight reduction of 3.8 kg reported. In contrast, the MedA group experienced a non-significant weight loss of 1.7 kg, and the control group only lost 0.5 kg.

Despite these significant weight loss outcomes, cognitive assessments across all groups revealed no meaningful differences. Cognitive functions, including attention, executive function, and memory, demonstrated only modest improvements, attributed primarily to practice effects rather than actual cognitive gain. Dr. Melissa Lamar, a cognitive researcher involved in the study, noted, "The lack of cognitive enhancement highlights the need for longer or more intensive dietary interventions to observe potential cognitive benefits."

The study also examined secondary outcomes such as blood pressure, insulin resistance, and inflammatory markers. While improvements were noted in metabolic health, including a significant reduction in visceral adipose tissue mass and improved diet adherence, these changes did not translate into cognitive benefits. Dr. Linda Schiffer, a nutrition expert and co-author of the study, emphasized that the results indicate the necessity for culturally sensitive dietary programs tailored to diverse populations, stating, "The practical implications of our findings suggest that while dietary quality can improve significantly, achieving cognitive benefits may require more extensive interventions."

The trial faced challenges due to the COVID-19 pandemic, which affected data collection methods, particularly for physical activity measures. Nevertheless, researchers were able to maintain a high level of participant engagement, with 88% of the original cohort contributing data at the 14-month mark.

In summary, the BRIDGE study reinforces the Mediterranean diet as a viable option for weight management and improved metabolic health among older adults, particularly in African American communities. However, it also indicates that more research is necessary to explore the cognitive impacts of dietary interventions. Future studies should consider longer durations and possibly incorporate additional lifestyle changes to better assess potential cognitive benefits. As Dr. McLeod concluded, "Understanding how dietary habits influence cognitive health in diverse populations is crucial for developing effective public health strategies."

The findings of this study are essential for informing dietary guidelines and interventions aimed at improving the health outcomes of older adults, particularly those at higher risk for obesity and cognitive decline.