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Bartonella spp. infection in people with Mild Cognitive Impairment: A pilot study
Verina Guirguis1,2, Francesca Pupillo1,2, Siena Rodrigues1,2
1Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America.
Abstract:
Mild Cognitive Impairment (MCI) is a neurological disorder at the transition between normal cognitive decline and dementia. Despite the potential role of neuroinflammation in the pathogenesis of MCI, infectious triggers remain mostly unknown. Infection with Bartonella spp., a zoonotic bacterium, has recently been associated with diffuse neurological and psychiatric symptoms. Given the preferential endothelial localization of Bartonella spp. and the role of vascular changes in neurocognitive decline, we hypothesized that there is an association between Bartonella spp. infection and pathologically accelerated decline in cognitive function in aging. To test this hypothesis, we collected serological and molecular markers of past and present Bartonella spp. infection in a sample of older people with and without MCI. Samples were processed in a blinded way to exclude laboratory biases. Contrary to our hypothesis, people with MCI were not more likely than people without MCI to have an active Bartonella spp. infection as measured by droplet digital PCR (p = 0.735) and quantitative PCR (p = 1). In addition, there was no significant difference in positive serological results between cases and controls (p = 0.461). Overall, higher-than-expected active Bartonella spp. infection (37% by ddPCR) and seroreactivity (71% by indirect fluorescent antibody assay) were found in people without MCI. Conclusions require caution, as our study was limited by the small number of cases with MCI. Overall, our results identified a higher than previously recognized rate of exposure and infection with Bartonella spp. in this older study population but does not support a specific role for such infection in MCI.
Insights
This study investigated Bartonella spp. infection in older adults with Mild Cognitive Impairment (MCI). Results showed no increased infection rates in MCI patients, suggesting Bartonella is not a significant factor in cognitive decline.
Area of Science:
- Neuroscience
- Infectious Diseases
- Gerontology
Background:
- Mild Cognitive Impairment (MCI) represents a critical stage between normal aging and dementia.
- Neuroinflammation is implicated in MCI, but infectious causes are largely unknown.
- Bartonella spp. infections, known for neurological symptoms, are explored for their potential role in cognitive decline.
Purpose of the Study:
- To investigate the association between Bartonella spp. infection and accelerated cognitive decline in aging.
- To determine if older adults with MCI are more likely to have active or past Bartonella spp. infections compared to controls.
Main Methods:
- Collected serological and molecular markers for Bartonella spp. infection in individuals with and without MCI.
- Utilized blinded sample processing to prevent laboratory bias.
- Employed droplet digital PCR (ddPCR) and quantitative PCR (qPCR) for active infection detection and indirect fluorescent antibody assay (IFA) for seroreactivity.
Main Results:
- No significant difference in active Bartonella spp. infection rates was found between MCI cases and controls (ddPCR: p = 0.735, qPCR: p = 1).
- Serological results also showed no significant difference between groups (p = 0.461).
- A higher than expected prevalence of active Bartonella spp. infection (37% by ddPCR) and seroreactivity (71% by IFA) was observed in the control group (without MCI).
Conclusions:
- The study did not find evidence supporting a specific role of Bartonella spp. infection in the pathogenesis of Mild Cognitive Impairment.
- A higher prevalence of Bartonella spp. exposure and infection was noted in the older study population than previously recognized.
- Further research with larger sample sizes, particularly for MCI cases, is warranted due to study limitations.
