The association of specific and cumulative exposure to infectious agents with cognitive impairment in older Hispanic adults

Background Accumulating evidence implicates infectious pathogens as triggers of immune–inflammatory processes that contribute to neurodegeneration. Inflammation in both the brain and peripheral circulation is recognized as a critical factor in the development and progression of cognitive decline and neurodegenerative disorders, including Alzheimer's disease. Objective This retrospective case-control study investigated the association between cognitive impairment and presence of serum antibodies to seven pathogens in older adults. Methods One hundred sixty-five participants aged ≥ 65 years from the Panama Aging Research Initiative Health Disparities (PARI-HD) study were evaluated. Presence of IgG antibodies against Toxoplasma gondii , Herpes Simplex Virus Type 1 (HSV-1), Human Cytomegalovirus (HCMV), Helicobacter pylori, Chlamydia pneumoniae, Treponema pallidum , and Trypanosoma cruzi was measured. Participant demographics, inflammatory biomarkers and cognitive-functional factors were analyzed for associations with single/multiple pathogen-specific antibodies reactivity using multivariable regression models. Results Only C. pneumoniae seropositivity was significantly different between cognitively unimpaired and impaired groups (p = 0.02) and increasing TNF-α levels were directly associated with C. pneumoniae seropositivity (OR = 2.08, CI 95% 1.0–4.1, p = 0.04). Additionally, cumulative exposure to infectious agents increased the likelihood of cognitive impairment (OR = 1.51, CI 95% 1.01–2.26, p = 0.04) and was associated with slower processing speed as measured by TMT A test (OR = 17.43, CI 95% 2.32–32.53, p = 0.02). Notably, the presence of C. pneumoniae in multiple pathogen interactions further raised the likelihood of cognitive impairment (OR = 4.07, CI 95% 1.24–13.36, p = 0.03). Conclusions These results enhance our understanding of cognitive impairment in a Hispanic population and underscore the need for further studies on the role of C. pneumoniae and multi-pathogen infection in Alzheimer's disease.