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.

Study Overview

• Status: Not yet recruiting
• Conditions: Cognitive Assessment; GI Health; Psychological Function
• Intervention / Treatment: Biological: Pecan snack; Biological: Pretzel snack

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: Chwan-Li (Leslie) Shen, PhD; Phone Number: 806-743-2815; Email: leslie.shen@ttuhsc.edu

Study Locations

• United States
  • Texas
    • Lubbock, Texas, United States, 79430
      • Texas Tech University Health Sciences Center
      • Contact: Chadley Coperland; Phone Number: 806-743-4752; Email: Chadley.Copeland@ttuhsc.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Pecan; 2.0 oz pecans daily for 3 months	Biological: Pecan snack; Pecan
Placebo Comparator: Pretzel; 3.5 oz pretzel snack daily for 3 months	Biological: Pretzel snack; Pretzel snack

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
fMRI measures	connectivity of amygdala seed regions and broader bilateral mPFC using fMRI	baseline and after 3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
NACC Uniform Data Set	overall neurocognitive functioning	baseline and after 3 months
Wisconsin Card Sorting Test	Cognition	baseline and after 3 months
California Verbal Learning Test	Memory and verbal learning	baseline and after 3 months
Clock Draw Test	Visuospatial functioning	baseline and after 3 months
TRAILS A and B	neuropsychological function	baseline and after 3 months
Geriatric Depression Scale (GDS-15)	Depression assessment	baseline and after 3 months
Beck Anxiety Inventory (BAI)	Anxiety assessment	baseline and after 3 months
fecal zonulin concentration by ELISA	Intestinal permeability marker	baseline and after 3 months
gut microbiome	fecal microbiome composition using 16S RNA sequencing	baseline and after 3 months
fecal metabolites	untargeted fecal metabolites by LC-MS analysis	baseline and after 3 months
neuroinflammation gene	whole blood neuroinflammation gene profiles	baseline and after 3 months

Collaborators and Investigators

• Sponsor: Texas Tech University Health Sciences Center
• Investigators: Principal Investigator: Chwan-Li (Leslie) Shen, PhD, Texas Tech University Health Sciences Center School of Medicine

Study record dates

Study Major Dates

• Study Start (Estimated): May 15, 2026
• Primary Completion (Estimated): September 30, 2028
• Study Completion (Estimated): September 30, 2028

Study Registration Dates

• First Submitted: December 29, 2025
• First Submitted That Met QC Criteria: January 12, 2026
• First Posted (Actual): January 16, 2026

Study Record Updates

• Last Update Posted (Actual): April 1, 2026
• Last Update Submitted That Met QC Criteria: March 30, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: fMRI; gut microbiome; neuroinflammation
• Additional Relevant MeSH Terms: Nervous System Diseases; Pathologic Processes; Inflammation; Pathological Conditions, Signs and Symptoms; Neuroinflammatory Diseases
• Other Study ID Numbers: IRB-FY2026-58

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: There is no plan to make IPD available due to HIPAA regulation.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No