UC Davis

Infections of herpes simplex virus type 1 (HSV-1), cytomegalovirus (CMV), Helicobacter pylori, and Chlamydia pneumoniae may play a role in cognitive decline via systemic inflammation. We hypothesized that Atherosclerosis Risk in Communities study participants who were seropositive in midlife for antibodies to HSV-1, CMV, H pylori, or C pneumoniae would have an accelerated rate of cognitive decline over 20 years. Atherosclerosis Risk in Communities performed a case-cohort study involving a stratified random sample of participants tested for serum immunoglobulin G antibodies to the pathogens of interest. We conducted a longitudinal study using this cohort. Cognitive change was measured using Z scores from the Delayed Word Recall (DWR), Digit Symbol Substitution (DSS), and Word Fluency (WF) Tests administered at visits 2 (1990-1992), 4 (1996-1998), and 5 (2011-2013). Linear regression models with generalized estimating equations and inverse probability of attrition weights were used to evaluate associations between infection and cognitive performance. Four hundred twenty-six participants were analyzed, of which 3% were seronegative for all 4 infections, 14% seropositive for one, 33% and 34% seropositive for 2 and 3, respectively, and 16% seropositive for all infections. At baseline, test scores were significantly lower for participants seropositive for H pylori and C pneumoniae. After baseline covariate adjustment, the rate of decline in DWR, DSS, WF, and global Z scores did not differ significantly by infection status for any of the 4 infections. There was also no significant association between the number of infections for which participants were seropositive and cognitive decline. Our study provides no evidence supporting a longitudinal relationship between seropositivity and cognitive decline.