Lactobacillus Plantarum Boosts Brain Power in Depression

observational-study PMID: 30388595

Lactobacillus Plantarum Boosts Brain Power in Depression

Quick Summary: A study tested a probiotic called Lactobacillus plantarum 299v (LP299v) in people with major depression who were already taking antidepressant meds. After 8 weeks, those taking the probiotic showed better memory and focus compared to a placebo group. It also lowered levels of a brain chemical linked to depression symptoms, marking the first evidence of these effects from a probiotic.

What The Research Found

Researchers explored how LP299v, a friendly gut bacteria, might help the brain in people with major depressive disorder (MDD). The gut-brain connection, known as the microbiota-gut-brain axis, plays a big role in mood and thinking skills. Here's what stood out:

Better Memory and Attention: People taking LP299v improved more on tests for attention (Attention and Perceptivity Test) and memory recall (California Verbal Learning Test). For example, they remembered more words over several tries compared to the placebo group.
Lower Kynurenine Levels: This probiotic cut down kynurenine (KYN), a substance from the amino acid tryptophan that's often high in depression and can harm brain function. It also boosted the ratio of another related chemical (3HKYN to KYN), which might protect the brain.
No Big Changes in Inflammation or Stress: Levels of body chemicals like tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1b), and cortisol stayed the same in both groups.
First-of-Its-Kind Results: This is the first study showing probiotics like LP299v can improve thinking skills and lower KYN in people with MDD.

These findings suggest LP299v works alongside standard antidepressants to target brain fog, a common issue in depression.

Study Details

This was a solid scientific setup to ensure fair results.

Who was studied: 79 adults with major depressive disorder (MDD), all on selective serotonin reuptake inhibitors (SSRIs) like common antidepressants. About 60 finished the full study—30 in the probiotic group and 30 in the placebo group.
How long: 8 weeks, with check-ins at the start and end to measure changes in mood, thinking, and blood markers.
What they took: Everyone kept their SSRI meds. The probiotic group added LP299v in daily capsules (exact dose and bacteria count not specified in the study). The placebo group got fake capsules that looked the same.

Doctors used tools like the Hamilton Depression Rating Scale for mood and various tests (Stroop Test, Trail Making Test) for brain function. They also checked blood for tryptophan breakdown products and stress markers.

What This Means For You

If you're dealing with depression, especially brain fog or trouble concentrating, this study offers hope. LP299v might enhance your antidepressant by supporting gut health, which influences your brain.

For Depression Sufferers: Adding a probiotic like this could help with memory and focus without changing your meds—talk to your doctor before trying.
Gut-Brain Link: Your gut bacteria affect mood; eating probiotic-rich foods (like yogurt) or supplements might give a natural boost, but LP299v is a specific strain shown to help here.
Everyday Tip: While not a cure, it highlights why a healthy gut matters for mental health. Start small with probiotic foods, but seek professional advice for depression treatment.

This isn't medical advice—always consult a healthcare provider for personalized steps.

Study Limitations

No study is perfect, and this one has points to watch:

Small Group: Only 60 people finished, so results might not apply to everyone; bigger studies are needed.
Short Timeframe: 8 weeks is a start, but we don't know if benefits last longer or fade after stopping.
Missing Details: The exact dose of LP299v wasn't shared, making it hard to replicate. Plus, no info on participants' ages, genders, or other health factors.
Unclear Mechanisms: It didn't lower inflammation or stress markers, so exactly how it helps the brain isn't fully explained—more research is key.

Overall, these promising results call for larger, longer trials to confirm if LP299v can be a go-to add-on for depression care.

Key Findings

Cognitive Improvement: LP299v supplementation significantly improved cognitive performance in MDD patients, as shown by enhanced scores in the Attention and Perceptivity Test (APT) and California Verbal Learning Test (CVLT) total recall (trials 1–5).
Kynurenine Pathway Modulation: LP299v reduced plasma kynurenine (KYN) concentrations and increased the 3-hydroxykynurenine (3HKYN):KYN ratio compared to placebo, suggesting altered tryptophan metabolism.
No Inflammatory or Stress Marker Changes: No significant differences were observed in TNF-α, IL-6, IL-1β, or cortisol levels between groups.
First Evidence: This is the first study to link probiotic use with cognitive enhancement and KYN reduction in MDD patients.

Study Design

Type: Double-blind, randomized, placebo-controlled clinical trial.
Population: 79 adults with major depressive disorder (MDD); 60 completed the study (30 in LP299v group, 30 in placebo group).
Duration: 8 weeks.
Methodology: Participants received either LP299v or placebo alongside selective serotonin reuptake inhibitors (SSRIs). Cognitive functions (APT, Stroop, RFFT, TMT, CVLT) and biochemical markers (KYN pathway metabolites, cytokines, cortisol) were measured pre- and post-intervention.

Dosage & Administration

Dose: The study details provided do not specify the exact dosage of Lactobacillus plantarum 299v administered.
Administration: Probiotic or placebo capsules were taken daily for 8 weeks, though the frequency (e.g., once vs. twice daily) and colony-forming units (CFU) were not reported in the provided summary.

Results & Efficacy

Cognitive Outcomes:
APT scores improved significantly in the LP299v group versus placebo (p < 0.05 unspecified).
CVLT total recall (trials 1–5) showed greater improvement with LP299v (p < 0.05 unspecified).
Biochemical Changes:
KYN concentration decreased significantly in the LP299v group (p < 0.05).
3HKYN:KYN ratio increased significantly with LP299v (p < 0.05), indicating a shift in tryptophan metabolism toward neuroprotective pathways.
No significant changes in TNF-α, IL-6, IL-1β, or cortisol levels.
Statistical Analysis: Repeated Measures ANOVA showed a significant interaction effect (Treatment × Time) for anthranilic acid (AA), but post hoc tests were non-significant.

Limitations

Sample Size: Only 60 participants completed the study (30/group), reducing statistical power.
Short Duration: 8 weeks may be insufficient to assess long-term effects or sustained cognitive benefits.
Incomplete Demographics: Age, gender, or baseline health metrics of participants were not detailed in the provided summary.
Unspecified Dosing: Lack of dosage and CFU information limits reproducibility.
Mixed Biochemical Results: No significant changes in inflammatory or stress markers despite cognitive improvements, suggesting potential mechanisms remain unclear.

Clinical Relevance

Cognitive Support: For MDD patients on SSRIs, LP299v may offer adjunctive benefits for cognitive deficits, a common unmet need in depression treatment.
Kynurenine Pathway Targeting: The reduction in KYN—a metabolite linked to neuroinflammation and glutamate dysregulation—highlights a novel mechanism for probiotic action in psychiatric disorders.
Need for Further Research: Larger trials with longer follow-up periods and dose-response analyses are required to confirm these findings and explore effects on mood symptoms.
Practical Implication: While promising, current evidence does not support LP299v as a standalone treatment but suggests it could complement standard therapies for cognitive symptoms in MDD.

Note: This analysis is restricted to the study details provided. Full interpretation requires access to raw data, dosing specifics, and statistical values (e.g., p-values, confidence intervals).