Septicemia is associated with increased risk for dementia: a population-based longitudinal study

Background: Systemic infection has been linked to cognitive impairment. We hypothesized that patients with septicemia are predisposed to increased risks for developing dementia in a long-term setting. Methods: This observational, retrospective, longitudinal, nation-wide populationbased study was conducted using the data deduced from Longitudinal Health Insurance Database (LHID) in Taiwan. All patients with septicemia hospitalized for the first time from 2001 to 2011 without prior dementia were included. The development of Alzheimer's disease (AD) or non-Alzheimer dementias (NAD) in relation to the development of septicemia for each patient was recorded. An ageand sex-matched cohort without septicemia and without prior dementia served as the control. Septicemia, dementia, and other confounding factors were defined according to International Classification of Diseases Clinical Modification Codes. Cox proportional-hazards regressions were utilized to analyze adjusted hazard ratios. Results: Patients with septicemia had a higher risk for developing dementia based on hazard ratios (HRs) (p< 0.001). Patients with septicemia in the younger age groups had a greater dementia risk (p< 0.01). Septicemia was associated with subsequent NAD (p< 0.001), whereas the increased risk of AD was statistically insignificant (p> 0.05). Furthermore, higher severity of septicemia was associated with increased risk of developing dementia. Conclusions: Our findings suggest that septicemia is associated with an increased risk in developing NAD but not AD. A likely causal role of septicemia in increasing the risk of NAD is suggested, according to the findings that patients with higher severity of septicemia carried greater risk of sustaining dementia.