Bidirectional Relationship between Cognitive Function and Pneumonia

Abstract

Rationale: Relationships between chronic health conditions and acute infections remain poorly understood. Preclinical studies suggest crosstalk between nervous and immune systems. Objectives: To determine bidirectional relationships between cognition and pneumonia. Methods: We conducted longitudinal analyses of a population-based cohort over 10 years. We determined whether changes in cognition increase risk of pneumonia hospitalization by trajectory analyses and joint modeling. We then determined whether pneumonia hospitalization increased risk of subsequent dementia using a Cox model with pneumonia as a time-varying covariate. Measurements and Main Results: Of the 5,888 participants, 639 (10.9%) were hospitalized with pneumonia at least once. Most participants had normal cognition before pneumonia. Three cognition trajectories were identified: no, minimal, and severe rapid decline. A greater proportion of participants hospitalized with pneumonia were on trajectories of minimal or severe decline before occurrence of pneumonia compared with those never hospitalized with pneumonia (proportion with no, minimal, and severe decline were 67.1%, 22.8%, and 10.0% vs. 76.0%, 19.3%, and 4.6% for participants with and without pneumonia, respectively; P , 0.001). Small subclinical changes in cognition increased risk of pneumonia, even in those with normal cognition and physical function before pneumonia (b ¼ 20.02; P , 0.001). Participants with pneumonia were subsequently at an increased risk of dementia (hazard ratio, 2.24 [95% confidence interval, 1.62-3.11]; P ¼ 0.01). Associations were independent of demographics, health behaviors, other chronic conditions, and physical function. Bidirectional relationship did not vary based on severity of disease, and similar associations were noted for those with severe sepsis and other infections. Conclusions: A bidirectional relationship exists between pneumonia and cognition and may explain how a single episode of infection in well-appearing older individuals accelerates decline in chronic health conditions and loss of functional independence. Keywords: pneumonia; dementia; cognitive functionApproximately half of all adults have a chronic health condition and these conditions are a leading cause of disability and death. A single episode of infection may also lead to a cascade of secondary illnesses, disability, and death (1-3). However, the relationship between chronic health conditions and infection remains poorly understood, particularly in community-dwelling individuals without major impairments in cognition or physical function.We examined the relationship between pneumonia and cognition because pneumonia and dementia are common and In this study, we demonstrate how changes in cognition over time, even small subclinical changes, are associated with an increased risk of pneumonia and within the same cohort we demonstrate that once participants develop pneumonia, they have an accelerated course to dementia. Similar patterns were seen in those with severe sepsis and when stratifie...

Association between dementia and discharge status in patients hospitalized with pneumonia

“…The reason for this finding remains unclear. Lung disease and impaired lung function are reportedly associated with inferior cognitive performance [37][38][39][40]. We speculate that impaired lung function brought about by pneumonia in patients with dementia may lead to a further decline in cognitive function, making it less likely that a patient will be able to return home.…”

Cognitive Function, Mental Health, and Health-related Quality of Life after Lung Transplantation

“…Confirmatory studies, designed to examine markers of oxidative stress (34,35), inflammation (e.g., IL-18) (35,(43)(44)(45), and oxygenation postoperatively as potential mediators of the observed relationships between allograft ischemic time, oxygenation, and cognitive function, are required to validate our observations. Related future studies are required to examine whether the previously identified relationship between prolonged allograft ischemic time and long-term survival (34) is mediated by cognitive impairment and the potential adverse events related to such impairment (i.e., functional impairment, medication nonadherence, infectious complications) (46,47). Importantly, given the collinearity between graft ischemic time and cardiopulmonary bypass time and the standard use of cardiopulmonary bypass for bilateral lung transplantation at this center, the use and duration of cardiopulmonary bypass remains a potentially modifiable risk factor for cognitive decline after lung transplantation (32,33).…”

Diagnoses of Early and Late Readmissions after Hospitalization for Pneumonia. A Systematic Review

“…Each year, 1.1 million patients are hospitalized with pneumonia, and the vast majority of patients survive to hospital discharge (2). Once believed to be an acute illness with minimal repercussions, pneumonia is increasingly recognized to be a fundamental turning point in patients' lives (3), resulting in new functional limitations (4), cognitive decline (4,5), and increased long-term mortality (3,(6)(7)(8). The causes of this persistent mortality burden remain unclear, and reasons for rehospitalization may identify important sources of morbidity in this population.…”