Snacks and Brain Health

September 3, 2026 updated by: Texas Tech University Health Sciences Center

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

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Texas
      • Lubbock, Texas, United States, 79430
        • Recruiting
        • Texas Tech University Health Sciences Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
fMRI measures
Time Frame: baseline and after 3 months
connectivity of amygdala seed regions and broader bilateral mPFC using fMRI
baseline and after 3 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
NACC Uniform Data Set
Time Frame: baseline and after 3 months
overall neurocognitive functioning
baseline and after 3 months
Wisconsin Card Sorting Test
Time Frame: baseline and after 3 months
Cognition
baseline and after 3 months
California Verbal Learning Test
Time Frame: baseline and after 3 months
Memory and verbal learning
baseline and after 3 months
Clock Draw Test
Time Frame: baseline and after 3 months
Visuospatial functioning
baseline and after 3 months
TRAILS A and B
Time Frame: baseline and after 3 months
neuropsychological function
baseline and after 3 months
Geriatric Depression Scale (GDS-15)
Time Frame: baseline and after 3 months
Depression assessment
baseline and after 3 months
Beck Anxiety Inventory (BAI)
Time Frame: baseline and after 3 months
Anxiety assessment
baseline and after 3 months
fecal zonulin concentration by ELISA
Time Frame: baseline and after 3 months
Intestinal permeability marker
baseline and after 3 months
gut microbiome
Time Frame: baseline and after 3 months
fecal microbiome composition using 16S RNA sequencing
baseline and after 3 months
fecal metabolites
Time Frame: baseline and after 3 months
untargeted fecal metabolites by LC-MS analysis
baseline and after 3 months
neuroinflammation gene
Time Frame: baseline and after 3 months
whole blood neuroinflammation gene profiles
baseline and after 3 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Texas Tech University Health Sciences Center

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Chwan-Li (Leslie) Shen, PhD, Texas Tech University Health Sciences Center School of Medicine

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 15, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 30, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 30, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 29, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 16, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 8, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 3, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings