Genetic predisposition to higher production of interleukin-6 through -174 G > C polymorphism predicts global cognitive decline in oldest-old with cognitive impairment no dementia

Abstract

Interleukin 6 (IL-6) is a pro-inflammatory cytokine upregulated in neurodegenerative contexts. The polymorphism IL-6 -174 G > C influences release levels of this cytokine. We aimed to evaluate the influence of IL-6 -174 G > C on global cognitive score of a group with cognitive impairment no dementia in one year of follow-up.Methods The subjects were categorized in two groups: short-term decline in global cognitive score and those with short-term stability or improvement. IL-6 174 G > C information were compared among these groups.Results We observed that individuals with cognitive impairment no dementia with GGlowergenotype were more frequent among global cognitive score non-decliners while carriers of at least one Chigherallele were more frequent in the group with global cognitive score decliners (p = 0.012; RR = 3.095 IC95%= 1.087-8.812).Conclusion These results suggest that the higher expression of IL-6 gene may be an independent risk factor for cognitive decline among individuals with cognitive impairment no dementia.

Exploring the Homeostatic and Sensory Roles of the Immune System

“…Low-grade systemic inflammation is associated with aging, and it has been described in patients with obsessive-compulsive disorder, major depression, bipolar disorder, Parkinson disease, and Alzheimer disease ( 50 – 53 ). Interleukin-6 (IL-6) was found to be increased systemically in patients suffering from these psychological diseases and correlates with the finding that old individuals that express more IL-6 develop cognitive decline more frequently ( 54 ). These findings indicate that the immune system detects homeostatic imbalances in the nervous system and is influenced by these imbalances, suggesting that homeostasis and function of immune and nervous systems are largely dependent on each other.…”

Polymorphisms in cytokine genes influence cognitive and functional performance in a population aged 75 years and above

“…Recently, we demonstrated that the SNP IL‐6 −74G > C is involved in short‐term cognitive decline among CIND individuals. In this way, carriers of the C higher allele showed a three higher risk for cognitive decline at the 1‐year follow‐up compared with individuals with the GG lower genotype (Fraga et al , ).…”

Lipoprotein-associated Phospholipase A2 Is Associated with Risk of Mild Cognitive Impairment in Chinese Patients with Type 2 Diabetes

“…IL-6 is a pro-inflammatory cytokine that participates in inflammatory reactions and immune response and influences the growth and differentiation of cells in the central nervous system. Various studies have indicated increased peripheral IL-6 levels to be associated with cognitive impairment 27 , 28 . Furthermore, studies have shown that IL-6 may directly inhibit human hippocampal neurogenesis 29 .…”