Snacks and Brain Health

Effects of Pecans on Brain Health in Older Americans With Mild Cognitive Impairment: Gut-brain Axis

This project will investigate whether daily snack consumption can improve memory, mood, and overall brain function in people with cognitive impairment. Sixty participants, aged 50 and older, with cognitive impairment, will be randomly assigned to eat snacks, either pecans or pretzels, for three months. Researchers will also study how snacks (pecans and pretzels) may influence the body, including changes in gut bacteria, blood markers of inflammation, and signals that connect the gut and the brain.

Inclusion Criteria:

• men and women > 50 years-old
• self-reported IQCODE (informant questionnaire on cognitive decline in the elderly) average score < 4.5
• self-reported significant functional impairment (related to cognitive impairment) in basic or advanced activities of daily living as evidenced by the Activities of Daily Living (ADLs) questionnaire. If answers to at least one endorsement in the "NO, dependence due to memory concerns".
• Stable medications (≥ 12-week unchanged dose before baseline) with no planned changes during trial.
• habitually consume less than two servings (2 ozs = 1/4 cup) of nuts or nut spreads per week
• willing to accept randomization

Exclusion Criteria:

• reported nut allergy or intolerance
• self-reported untreated hypothyroidism, severe liver disease, or end-stage chronic kidney disease
• heavy alcohol drinker: in the past 3 months: men ≥14 drinks/week or women ≥7 drinks/week
• recent (<1 month) appearance of diarrhea or hematochezia before study intervention begins. Rationale: A one-month waiting period after diarrhea or hematochezia (blood in stool) is recommended for a gut microbiome test to ensure the results accurately reflect the state and microbial composition, since diarrhea and hematochezia can significantly alter the gut environment and skew test results.
• recent (<1 month) exposure to antibiotics before study intervention begins. Rationale: A one-month waiting period after antibiotics is recommended for a gut microbiome test because it allows the microbial community time to recover and reach a more stable state, ensuring a more accurate and representative snapshot of the gut microbiome composition, since antibiotic usage can significantly reduce microbial diversity.
• Self-reported unstable GI disorder
• likeliness of moving during the trial, lack of transportation, or unavailability at sample collection times