Mediterranean Diet, Weight Loss, and Cognition in Obese Older Adults
- Principal Investigator
- Fitzgibbon, Marian L.
- Start Date
- End Date
Obesity is a leading cause of death and disability in the United States, affecting as many as 80 million Americans. It is well-established that obesity contributes to a number of risk factors for metabolic abnormalities and cardiovascular disease (CVD), including hypertension, diabetes, and hyperlipidemia. In addition, there is growing evidence that obesity is associated with cognitive deficits in multiple domains, even in otherwise healthy older adults.
With the rapidly aging US population and the high prevalence of obesity among older adults, innovative strategies to prevent cognitive decline in this population are needed. Dietary patterns are central to the development and maintenance of obesity and evidence suggests that dietary factors also may affect cognition. Epidemiologic studies have shown that adherence to a Mediterranean diet is associated with less cognitive decline and reduced risk for dementia. Weight loss through caloric restriction also has been shown to improve cognitive function in obese adults. The identification of effective lifestyle interventions for diet/weight management to improve cognition among obese older adults is a public health priority.
However, to our knowledge, no randomized clinical trials have examined the effect of the Mediterranean diet, with and without caloric restriction, to promote weight loss on cognitive functioning in obese older adults. This study intends to address this question.
In this eight-month trial, we randomize 180 adults aged 55 years and older with a body mass index of 30 to 50 kg/m² to one of three conditions:
- Mediterranean diet alone, without caloric restriction/weight loss (MedDiet-A);
- Mediterranean diet, plus a lifestyle intervention with caloric restriction/weight loss (MedDiet-WL); or
- Typical diet control (TDC) without caloric restriction/weight loss.
We will test the following hypotheses:
- Any participant who follows the Mediterranean diet (both the MedDiet-A and MedDiet-WL groups) will achieve greater improvements in cognition compared to the group adhering to typical diet control (TDC).
- Those in the MedDiet-WL group -- who follow the Mediterranean diet and participate in the lifestyle intervention -- will exhibit greater improvements in cognition compared to participants who eat a Mediterranean diet without restricting their calories or losing weight (i.e., the MedDiet-A group).
- Participants in the groups that follow the Mediterranean diet (those in either MedDiet-A or MedDiet-WL) will show greater improvements in cardiovascular and metabolic risk factors, systemic inflammation, oxidative stress (OxStress), and body weight/composition compared to study participants under typical diet control.
- Those who are following the Mediterranean diet while engaging in a lifestyle intervention and restricting calories or losing weight (the MedDiet-WL group) will exhibit greater improvements in cardiovascular/metabolic risk factors, systemic inflammation, OxStress, and body weight/composition compared to study participants who only follow the Mediterranean diet (MedDiet-A).
We will examine potential moderators of treatment (e.g., ethnicity and baseline cognitive function) and explore mediators by which neurocognition is improved by diet, including changes in CVD/metabolic risk factors, physical activity, systemic inflammation, and OxStress. We will determine the extent to which changes in dietary habits, weight, and cognitive functioning are maintained over a 6-month follow-up period.
National Heart, Lung, and Blood Institute of the National Institutes of Health (Grant No. R01HL129153)
Tussing-Humphreys L, Lamar M, Blumenthal JA, Babyak M, Fantuzzi G, Blumstein L, Schiffer L, Fitzgibbon ML. Building research in diet and cognition: The BRIDGE randomized controlled trial. Contemp Clin Trials. 2017 Aug;59:87-97. [See abstract.]