Overview

This pilot randomized, double-blind, crossover clinical trial will evaluate the effect of a synbiotic containing Lactobacillus acidophilus LA-5 and agave inulin on mild cognitive impairment (MCI) in adults aged 60-75 years attending the Defense Medical Specialties Unit. Forty participants with MCI will be randomized into two groups of 20 participants. The intervention will consist of daily administration of L. acidophilus LA-5 (4 × 10⁹ CFU), 7 g of agave inulin, and almond powder for 12 weeks, while the control group will receive almond powder as the vehicle. After a two-week washout period, participants will cross over to the alternate intervention for an additional 12 weeks.

Cognitive function will be assessed using the Montreal Cognitive Assessment (MoCA), Memory Alteration Test (M@T), and Mini-Mental State Examination (MMSE). Secondary assessments will explore potential mechanisms of the microbiota-gut-brain axis by measuring fecal L. acidophilus LA-5 and butyrate, as well as serum BDNF and inflammatory biomarkers including IL-1β, IL-6, IL-10, and TNF-α.

The study aims to determine whether synbiotic supplementation improves cognitive performance in older adults with MCI and whether these changes are accompanied by modifications in gut microbial activity, short-chain fatty acid production, neurotrophic signaling, and systemic inflammation.

Eligibility

Inclusion Criteria:

• Adults aged 60 to 75 years.
• Presence of mild cognitive impairment (MCI) determined by neuropsychological testing, meeting at least two of the following three established cutoff criteria:
• Montreal Cognitive Assessment (MoCA): 19-26 points.
• Memory Alteration Test (M@T): 28-37 points.
• Mini-Mental State Examination (MMSE): 12-24 points.
• Ability and willingness to provide written informed consent; consent may be provided by a family member or legal representative when necessary.

Exclusion Criteria:

• Previous diagnosis of severe cognitive impairment, Alzheimer disease, vascular dementia, or another neurodegenerative disorder affecting cognition.
• History of cerebral ischemia, cerebrovascular events, traumatic brain injury, or advanced-stage renal disease.
• Diagnosis of type 2 diabetes mellitus.
• Diagnosed dysbiosis or inflammatory bowel disease, including ulcerative colitis or Crohn disease.
• Use of antibiotics, laxatives, probiotics, or prebiotics within the 3 months prior to enrollment.
• Habitual consumption of fermented foods or fiber-rich supplements, particularly fiber intake \>18 g/day.
• Excessive alcohol consumption, defined as ≥2 alcoholic drinks per day, or history of alcohol dependence.
• Chronic use of medications that may interfere with the microbiota-gut-brain axis, including immunosuppressants, antipsychotics, or corticosteroids.
• Recent surgery within the previous 3 months or a planned medical intervention during the study period.
• Known adverse reaction or hypersensitivity to any component of the synbiotic or to almond powder.
• Uncontrolled chronic stress identified by clinical assessment.
• Participation in intense physical activity or high-performance sports during the study.