Investigating the Link Between Infections and Dementia
Post by Megan McCullough
The takeaway
There was no link found between common infections and cognitive decline later in life in a large cohort of individuals.
What's the science?
Common infections such as sepsis, pneumonia, and urinary tract infections, have previously been linked to dementia. Although this research has shown an association between infections and cognitive decline, there is limited information on the precise relationship. There might also be a link between infections and neuroimaging markers for dementia such as hippocampal atrophy and white matter hyperintensities (WMH), but data is limited. This week in Translational Psychiatry, Muzambia and colleagues aimed to address these gaps in research by exploring the association between common infections, cognitive decline over time, and neuroimaging markers, using data from the UK Biobank study.
How did they do it?
The authors recruited participants from the UK Biobank study, a large database with medical information for over half a million individuals across the UK. The authors used data from participants within this study that had primary and secondary care data for at least a year and no history of dementia or cognitive problems. The larger study population was divided into two cohorts: a group with baseline data for cognitive function (16,728 participants), and a group with baseline data for neuroimaging (14,712 participants). To measure cognition, participants completed tests that measured reaction time, visual memory, fluid intelligence, and prospective memory. For the neuroimaging measures, the authors looked at hippocampal volume and WMH; markers for preclinical dementia. Participants with and without infections in the five years before baseline tests were included in the study to measure any link between infections and cognitive and neuroimaging markers for dementia. The cognitive assessments were repeated over time to measure any cognitive decline. Linear regression models were then used to match presence of infection to changes in cognitive function and to any appearance of neuroimaging markers associated with dementia.
What did they find?
The authors found no link between having an infection and cognitive decline over time except for a small association between the presence of an infection and performance on the visual memory test over time. There was also no association found between infection and hippocampal atrophy or WMH. The UK Biobank study provided vast amounts of demographic and lifestyle information for participants which allowed the authors to adjust for many confounding variables in these analyses.
What's the impact?
This study is the largest longitudinal study thus far to examine the link between contracting common infections and the development of dementia markers. Overall, the data in the study does not support a link between infections and developing dementia. Although this singular study doesn’t rule out the possibility of a link, these data suggest that other factors are likely more important in the development of dementia.