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 GGlower genotype were more frequent among global cognitive score non-decliners while carriers of at least one Chigher allele 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.