As mentioned earlier in this issue of TreatmentUpdate, experiments with animals suggest that bacteria in the gut can somehow affect memory and mood. These experiments involved giving the animals antibiotics to wipe out their intestinal bacteria or some of their intestinal bacteria, as well as other experiments where supplements of friendly bacteria were given.

Researchers in Rome, Italy, conducted a six-month pilot study with a sophisticated mix of friendly bacteria (Visbiome, Vivomixx) to assess their impact on memory and thinking processes in 10 HIV-positive people who had been taking HIV treatment (ART) for several years and had undetectable viral loads.

The researchers found that there was significant improvement in several neuropsychological test results over time, including memory and verbal fluency. They also found that there was a decrease in anxiety. The probiotic was safe. The study’s small size and other design limitations mean that its results are suggestive, not definitive. However, the results of this study can be used to design larger studies of Visbiome to confirm these findings.

Study details

Researchers recruited HIV-positive adults who did not have diagnoses of the following:

• intestinal disorders
• neurological disorders
• mental health conditions
• cancer

Participants had samples of the fluid that surrounds the brain and spinal cord (cerebrospinal fluid, or CSF) removed before and after the study for analysis.

Participants took Visbiome twice daily. Visbiome contains the following bacteria:

• Lactobacillus plantarum
• Streptococcus thermophilus
• Bifidobacterium breve
• Lactobacillus paracasei
• Lactobacillus delbrueckii, subspecies bulgaris
• Lactobacillus acidophilus
• Bifidobacterium longum
• Bifidobacterium infantis

Participants underwent complex neurological testing at the beginning and end of the study.

The average profile of participants upon entering the study was as follows:

• all male
• age – 42 years
• duration of ART – six years
• all participants had an undetectable viral load for at least the past year
• CD4+ count – 674 cells/mm³

Results

Visbiome was well tolerated and no side effects were reported. Furthermore, analysis of CSF samples found no increase in inflammation in the blood or brain.

Researchers found that the level of bifidobacteria in the stool samples of participants rose significantly during the study, suggesting that participants were taking Visbiome.

Neuropsychological testing

Researchers found that there were some improvements in memory, verbal fluency and anxiety. However, they were cautious about the apparent change in measures of anxiety—they felt it was possible that participants may have become more aware of their feelings from being asked questions about anxiety and that perhaps the changes reported were influenced by the questioning.

Bear in mind

The results of the present study are promising but not definitive. A more robust study design will be needed before researchers can be certain about Visbiome’s usefulness.

—Sean R. Hosein

REFERENCES:

1. Ceccarelli G, Fratino M, Selvaggi C, et al. A pilot study on the effects of probiotic supplementation on neuropsychological performance and microRNA-29a-c levels in antiretroviral-treated HIV-1-infected patients. Brain and Behavior. 2017 Jul 16;7(8):e00756.
2. Bauer KC, Huus KE, Finlay BB. Microbes and the mind: emerging hallmarks of the gut microbiota-brain axis. Cellular Microbiology. 2016 May;18(5):632-644.
3. Yarandi SS, Peterson DA, Treisman GJ, et al. Modulatory effects of gut microbiota on the central nervous system: How gut could play a role in neuropsychiatric health and diseases. Journal of Neurogastroenrology and Motility Association. 2016 Apr 30;22(2):201-212.