Aging
Conditions
Keywords
fatty acids, diet, aging, MRI, palmitic acid, oleic acid
Brief summary
In this crossover study, the investigtors will administer two experimental diets in a random order for one week, and each experimental diet will be preceded by a one-week, low fat control diet for a total four-week study period. The goal is to study how the fatty acid content of the diet affects brain functioning in healthy adults aged 65-75 years. One experimental diet will have a high palmitic acid (PA)/oleic acid (OA) ratio (HPA), typical of the North American diet. The other experimental diet will have a low PA/OA ratio (HOA), typical of the Mediterranean Diet. All allowed food and drink (except water) will be provided by the investigative team, and compliance will be enhanced by constant, intense dietary surveillance by a registered dietitian.
Detailed description
This study will examine how manipulating dietary fatty acids affects brain functioning in older adults. Prior studies have shown that there are behavioral changes that can be made to improve cognition in adults on an acute time scale including improving sleep and physical activity. Based on preclinical data and prior studies in humans the investigators propose that brain functioning also can be acutely improved with a reduction in dietary saturated fat. This approach will first be used in cognitively normal older adults without dementia, but in the future it may be that improving baseline cognition is beneficial in patients with mild cognitive impairment and Alzheimer's disease even if the overall course of the patient's neurological condition is increasingly impaired cognitive function. The investigators will manipulate the dietary ratios of palmitic acid (PA) and oleic acid (OA), which are the most prevalent saturated and monounsaturated fatty acids, respectively in the diet and body lipids. Using a crossover study of men and women, aged 65-75 years, the investigators will administer two experimental diets in a random order for one week and each experimental diet will be preceded by a one-week, low fat control diet for a four-week total study period. One experimental diet will have a high PA/OA ratio typical of the usual North American Diet and the other experimental diet will have a low PA/OA ratio typical of the Mediterranean Diet. The following primary outcomes will be assessed: working memory performance, activation of working memory networks using functional magnetic resonance imaging (fMRI) and functional connectivity. The impact of this study is that these data may suggest one mechanism for acutely improving cognition in healthy older adults and potentially in those with cognitive impairment such as mild cognitive impairment and Alzheimer's disease. While changing dietary behavior long term requires additional investigation, there are potential immediate benefits to acute improvements in cognition on quality of life for older adults.
Interventions
DIETARY_SUPPLEMENTHigh Oleic Acid Diet
Subjects are provided with all food for each meal every day. The food is low in fat. In addition, subjects are provided with an oil mix that is 100% hazelnut oil. They will be taught to consume the oil with each meal and mix it in with the food provided.
DIETARY_SUPPLEMENTHigh Palmitic Acid Diet
Subjects are provided with all food for each meal every day. The food is low in fat. In addition, subjects are provided with an oil mix that is palm oil-89%, peanut oil-6.75%, and virgin olive oil-4.25%; . They will be taught to consume the oil with each meal and mix it in with the food provided.
Sponsors
University of Vermont
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
Each of the two experimental diets will be masked and only the dietician and statistician will be unblinded. Subjects will be assigned to one of two diet orders and the masking will be matched across the sexes.
Intervention model description
In this crossover study, the investigators will administer two experimental diets in a random order for one week, and each experimental diet will be preceded by a one-week, low fat control diet for a total four-week study period.
Eligibility
Sex/Gender
ALL
Age
65 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
* Men and women age range 65-75 years * Normal cognition (see Research Strategy for details on cognitive assessments) * Healthy (body mass index (BMI) of 20-40 kg/m2)
Exclusion criteria
* Significant cognitive or behavioral impairment (see Research Strategy for testing and exclusions) or pharmacological treatment for this (e.g. antipsychotics, anxiolytics, and sedative medications). * Hormone replacement therapy, past 3 months. * Hyper-androgenic condition. * HbA1C≥7.5% and or Fasting plasma glucose concentration ≥130 mg/dL. * Type 2 Diabetes if receiving any other therapy than metformin. * Use of nicotine or ingestion of caffeine or alcohol during the study. * Habitual fat intake \< 25% of kcal or strict vegetarian diet. * Sleep apnea requiring continuous positive airway pressure at night. * Lung, cardiac (heart failure or its treatment), liver disease, renal disease, cancer, and any other medical disorder known or thought to cause inflammation or abnormalities of cognition * Actively training for an athletic event or participating in competitive sports (such as league play or tournaments) * Intolerance or allergy to any of the food provided in the study.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Working Memory Performance | after 7 days of each diet | Accuracy for performance on the Nback working memory test during fMRI |
| Working Memory Brain Activation | after 7 days of each diet | Blood Oxygen Level Dependent (BOLD) activation during the Nback working memory test during fMRI |
| Working Memory Brain Functional Connectivity | after 7 days of each diet | BOLD functional connectivity during resting state fMRI |
Countries
United States
Contacts
Primary ContactJulie Dumas, Ph.D.
Backup ContactJenna Makarewicz, B.S.
Outcome results
None listed