Interleukin-6 as Predictor of One-Year Cognitive Function After Ischemic Stroke or TIA

Risk factors and predictive markers of post-stroke cognitive decline-A mini review

Stroke is one of the top causes of death and disability worldwide. Cognitive impairments are found in more than 70% of individuals who have survived a stroke. Cognitive decline is a major contributor to disability, dependency, and morbidity. The prevalence and severity of dementia vary depending on different characteristics of the stroke and other clinical risk factors. Here we discuss the effects of stroke territory, patients' age, sex, cerebral blood flow, acute reperfusion therapy, and cognitive reserve of post-stroke cognitive decline. Potential predictive molecular and genetic biomarkers of post-stroke cognitive impairments are also discussed.

Looking Upstream to Understand Race/Ethnicity as a Moderator for Poststroke Neuroinflammation and a Social Determinant for Poststroke Aphasia Outcomes

INTRODUCTION

Over the past decade, the stroke literature has begun to acknowledge and explore explanations for longstanding racial/ethnic differences in stroke outcomes. Poststroke cognitive impairment (PSCI) and poststroke aphasia are two such negative poststroke outcomes where racial/ethnic differences exist. Physiological differences, such as stroke type and lesion size, have been used to partially explain the variation in PSCI and aphasia. However, there is some evidence, although limited, that suggests neuroinflammatory processes as part of allostatic load may be a key contributor to the observed disparities.

METHOD

In this tutorial, we explore the influence of race differences in inflammation on poststroke cognitive outcomes. We suggest lifetime stress and other external determinants of health such as neighborhood environment and discriminatory practices through "weathering" explain differences in inflammation. While using an allostatic load framework, we explore the literature focusing specifically on the role of neuroinflammation on poststroke outcomes.

CONCLUSIONS

Examination of the immune response poststroke provides a foundation for understanding the mechanisms of PSCI and poststroke aphasia and the potential contributions of neuroinflammatory processes on poststroke cognitive outcomes. Furthermore, understanding of racial differences in those processes may contribute to a better understanding of racial disparities in general stroke outcomes as well as poststroke aphasia.

Prediction of poststroke cognitive impairment based on the systemic inflammatory response index

BACKGROUND

Poststroke cognitive impairment (PSCI) is a prevalent complication among stroke survivors. Although the systemic inflammatory response index (SIRI) has been shown to be a reliable predictor of a variety of inflammatory diseases, the association between the SIRI and PSCI is still unclear. Therefore, the purpose of this study was to investigate the relationship between SIRI and PSCI, and to design a nomogram to predict the risk of PSCI in acute ischemic stroke (AIS) patients.

METHODS

A total of 1342 patients with AIS were included in the study. Using the Mini-Mental State Examination scale, patients were separated into PSCI and non-PSCI groups within 2 weeks of stroke. Clinical data and SIRI values were compared between the groups. We developed the optimal nomogram for predicting PSCI using multivariate logistic regression. Finally, the nomogram was validated using the receiver operating characteristic curve, calibration curve, and decision curve analysis (DCA).

RESULTS

In total, 690 (51.4%) patients were diagnosed with PSCI. After adjusting for potential confounders, the SIRI (OR = 1.226, OR: 1.095-1.373, p < .001) was shown to be an independent risk factor for PSCI in the logistic regression analysis. The nomogram based on patient gender, age, admission National Institutes of Health Stroke Scale scores, education, diabetes mellitus, and SIRI had good discriminative ability with an area under the curve (AUC) of 0.716. The calibration curve and Hosmer-Lemeshow test revealed excellent predictive accuracy for the nomogram. Finally, the DCA showed the good clinical utility of the model.

CONCLUSION

Increased SIRI on admission is correlated with PSCI, and the nomogram built with SIRI as one of the predictors can help identify PSCI early.

Cognitive impairment and changes of red blood cell components and serum levels of IL-6, IL-18, and L-tryptophan in methamphetamine abusers

The deficit in cognitive function is more concerning in methamphetamine (MA) users. The cognitive deficit was suspected to be the consequence of neuroinflammation-induced neurological dysregulation. In addition, activating the key enzyme in the tryptophan metabolic pathway by pro-inflammatory cytokines results in metabolite toxicity, further generating cognitive impairments. However, the evidence for the role of neuroinflammation and tryptophan metabolites involved in MA-induced cognitive deficit needs more conclusive study.

OBJECTIVES

This retrospective study aimed to determine blood-inflammatory markers, tryptophan metabolite-related molecules, and cognitive function in MA abusers compared to healthy control (HC) participants.

METHODS

The cognitive functions were evaluated using Stroop, Go/No-Go, One Back Task (OBT), and Wisconsin Card Sorting Test-64 (WCST-64). Blood samples were analyzed for complete blood count (CBC) analysis, serum inflammatory cytokines interleukin (IL)-6 and IL-18 and tryptophan metabolites.

RESULTS

MA group exhibited poor cognitive performance in selective attention, inhibition, working memory, cognitive flexibility, concept formation and processing speed compared to HC. Reduction in red blood cell (RBC) components but induction in white blood cells (WBCs) and IL-6 were observed in MA abusers, which might indicate anemia of (systemic chronic low-grade) inflammation. In addition, the depletion of precursor in the tryptophan metabolic pathway, L-tryptophan was also observed in MA users, which might represent induction in tryptophan metabolites.

CONCLUSION

These findings emphasize that blood biomarkers might be a surrogate marker to predict the role of neuroinflammation and abnormal tryptophan metabolite in MA-induced cognitive impairments.

Development of Post-Stroke Cognitive and Depressive Disturbances: Associations with Neurohumoral Indices

Neuropsychiatric complications, in particular cognitive and depressive disorders, are common consequences of ischemic stroke (IS) and complicate the rehabilitation, quality of life, and social adaptation of patients. The hypothalamic-pituitary-adrenal (HPA) system, sympathoadrenal medullary system (SAMS), and inflammatory processes are believed to be involved in the pathogenesis of these disorders. This study aimed to explore these systems in IS patients, including those with post-stroke cognitive and depressive disorders, within a year after IS. Indices of the HPA axis, inflammatory system, and SAMS were measured in blood serum (cortisol, interleukin-6 (IL-6)), plasma (adrenocorticotropic hormone), and saliva (cortisol, α-amylase). During one year after mild/moderate IS (NIHSS score 5.9 ± 4.3), serum cortisol and salivary α-amylase levels remained elevated in the total cohort. In the group with further cognitive decline, serum and salivary cortisol levels were elevated during the acute period of IS. In the group with poststroke depressive disorder, salivary α-amylase was constantly elevated, while serum IL-6 was minimal during the acute period. The results suggest prolonged hyperactivation of the HPA axis and SAMS after IS. Specifically, post-stroke cognitive impairment was associated with hyperactivation of the HPA axis during the acute IS period, while post-stroke depressive disorder was associated with the chronic inflammatory process and hyperactivation of SAMS during the follow-up period.