Infection, inflammation and post-stroke cognitive impairment

Abstract

ABSTRACTBackgroundInfection and inflammation are risk factors for dementia in population-based cohorts, however studies in stroke are scarce. We determined the prevalence of stroke-associated infection and routinely measured inflammatory biomarkers during hospitalization for stroke, and their associations with global and domain-specific cognition acutely and at 6-months.MethodsA prospective stroke cohort completed the Oxford Cognitive Screen ≤2 weeks and at 6 months. Global post-stroke cognitive impairment (PSCI) was defined as proportion of domains impaired and domain-specific impairment was binarized as present/absent. Infection, inflammatory markers (C-reactive protein-CRP, white cell count-WCC, and neutrophil/lymphocyte ratio-NLR), and systemic inflammatory response syndrome-SIRS, were ascertained throughout admission through linkage to electronic patient records-EPRs supplemented by hand-searches. Associations of infection, inflammatory markers, and SIRS, with acute and 6-month global and domain-specific cognitive impairment were analyzed using multivariable regression adjusting for demographic/vascular factors and stroke severity.ResultsAmong 255 patients (mean/SD age=73.9/12.6 years, 46.3% female, mean/SD education=12.6/3.7 years, median NIHSS=5, range 0–30), infection was present in 90 (35.3%) patients at mean/SD 4.4/6.9 days post-stroke, most commonly pneumonia (47/90, 52%) and urinary tract infection (39/90, 43%). Admission WCC was elevated in 64 (25.1%, mean/SD=9.5/3.2×109/L), CRP in 105 (41.2%, mean/SD=27.5/50.9 mg/L), NLR in 97 (55.7%, mean/SD=5.5/4.5) and SIRS in 53 (26.6% with 45.2% positive overall during admission). Infection was associated with acute and 6-month PSCI (p<0.05adj) with stronger associations acutely for severe infection (infection+SIRS,p=0.02adj). Acute impairments in language, executive function and attention domains and 6-month impairment in number processing (allp<0.05adj) were associated with infection. No significant relationships were found for any biomarker and cognitive impairment.ConclusionInfection and elevations in routinely measured inflammatory biomarkers are common after stroke, however only infection is a risk factor for PSCI, suggesting that the rise in these biomarkers may be non-specific. Infection may present a tractable target for reducing PSCI.