Effects of prebiotics on gut and brain health in older adults with cognitive decline

Gut-brain Health Effects of PREbiotics in Older Adults With Suspected COgnitive DEcline: The PRECODE Study

Not applicable Interventional Wageningen University · NCT06433037

This study is testing whether three types of dietary fibers can improve gut and brain health in older adults who are noticing memory problems.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment164 (estimated)
Ages60 Years to 79 Years
SexAll
SponsorWageningen University Academic / other
Locations1 site (Wageningen)
Trial IDNCT06433037 on ClinicalTrials.gov

What this trial studies

This clinical trial investigates the impact of three different dietary fibers—chicory inulin, resistant dextrin, and seaweed polysaccharide—on gut and brain health in older adults aged 60 to 79 who experience subjective cognitive decline. Participants will receive either the dietary fibers or a placebo over a 26-week period. The study aims to explore the connection between gut health and cognitive function, particularly in relation to the gut-brain axis, which may play a role in preventing further cognitive decline. The findings could provide insights into dietary interventions for improving mental health in aging populations.

Who should consider this trial

Good fit: Ideal candidates are older adults aged 60-79 who report cognitive decline and have at least two risk factors for cognitive impairment.

Not a fit: Patients who are currently participating in other intervention trials or are technologically illiterate may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to dietary recommendations that improve cognitive health and potentially delay the onset of dementia in older adults.

How similar studies have performed: While the gut-brain axis is a growing area of research, this specific approach using dietary fibers in older adults with subjective cognitive decline is relatively novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Written informed consent
2. Fluency in Dutch (speaking, reading, writing)
3. Age between 60-79 years (at screening)
4. Subjective cognitive decline plus (SCD+), (criteria of Jessen et al.):

4.1 Self-reported worsening of memory; 4.2 Indication of repetitive concerns (worries) associated with SCD; 4.3 With at least one of the following two features present: (i) onset of SCD within the last 5 years; (ii) age at onset ≥60 years of age;

5. Presence of at least 2 self-reported risk factors for cognitive decline (based on LIBRA criteria): (i) Diabetes mellitus type II (ii) High cholesterol (iii) Hypertension (iv) High BMI (v) Heart disease (vi) Unhealthy diet (lower regular adherence to Mediterranean diet components such as fish, vegetables, olive oil, pasta and red wine)

Exclusion Criteria:

1. Current participation in other intervention trials
2. Technologically illiterate (complete incompetence in working with computers, apps, online questionnaires, smartwatches etc.)
3. No internet access from home
4. Clinical diagnosis of ≥1 of the following:

   * Neurological pathology (e.g. MCI, dementia, multiple sclerosis, Parkinson's disease, epilepsy);
   * Current malignant disease(s), with or without treatment;
   * Current psychiatric disorder(s) (e.g. major depressive disorder, bipolar disorder, schizophrenia, anxiety, psychosis, PTSD);
   * Symptomatic/decompensated cardiovascular disease (e.g. stroke, angina pectoris, heart failure, recent myocardial infarction);
   * Severe visual impairment or blindness
   * Hearing or communicative impairment.
   * Gastrointestinal tract disorder such as irritable bowel syndrome or inflammatory bowel disease (e.g. Crohn's disease or ulcerative colitis).
5. Current or recent (\<6 weeks) use of prebiotic, probiotic, or dietary fibre supplement that may modulate the microbiota, or unwilling to stop the use of supplements during the study
6. Current or recent (\<6 weeks) of algae/phytoplankton supplements such as spirulina or chlorella, or unwilling to stop the use of supplements during the study
7. Use of psychotropic medication (anti-depressants, anti-psychotics)
8. Use of antibiotics in the 3 months before starting the study or planned use during the study
9. Being an employee of the Human Nutrition and Health Division of Wageningen University.
10. Significant cognitive impairment assessed using the Modified Telephone Interview for Cognitive Status battery (TICS-m score \<23)
11. Request to have Apo-E genotype result disclosed
12. Allergies to fish or shellfish
13. Having a contra-indication to MRI scanning including:

    * Ferromagnetic implants:

      * Active implantable medical devices such as: insulin pump / medicine pump / neurostimulator; pacemaker / defibrillator;
      * Other passive implants such as: punctured port-a-cath; synthetic heart valve
    * Intra-orbital or intra-ocular metallic fragments
    * Claustrophobia

Where this trial is running

Wageningen

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Subjective Cognitive Declinegut-brain axisworking memorygut healthdietary fibresprebiotics
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.