Building research in diet and cognition: The BRIDGE randomized controlled trial

Obesity has been linked to cognitive impairment, cognitive decline and dementia. Given that 38.5% of U.S. adults 60years and older are obese and these numbers are rapidly increasing, strategies to decouple obesity from cognitive decline are needed. Innovative lifestyle strategies that may postpone the onset of subclinical symptoms or even arrest the transition to overt dementia in at-risk individuals are critically needed. Poor diet is central to the development of obesity and diet may affect cognition. Adherence to a Mediterranean Diet (MedDiet) is associated with reduced risk of cognitive impairment and dementia. Furthermore, weight loss through caloric restriction improves cognitive function. This paper describes the Building Research in Diet and CoGnition (BRIDGE) study, a randomized trial examining the effect of the MedDiet, with and without weight loss, on cognitive functioning in obese older adults. Obese (BMI≥30 and ≤50kg/m²) older adults (≥55years) (n=180) will be randomized in a 2:2:1 allocation scheme to: Typical Diet Control; MedDiet alone, without weight loss; or MedDiet lifestyle intervention to promote weight loss and weight loss maintenance. Both MedDiet intervention groups will meet for one individual session and 27 group sessions over an 8-month period. Individuals in the control group will not receive instruction on changing lifestyle habits. Outcomes will be assessed at baseline, 8 and 14months. The primary outcome is cognitive functioning; secondary outcomes will include changes in body weight, diet, cardiovascular, metabolic, and inflammatory biomarkers.