Antioxidants and Biomarkers of Inflammation as Risk Factors of Vascular Cognitive Impairment in Adult Hypertensives

Abstract

Background: Impairment in cognition and attention involving memory loss characterize Vascular Cognitive Impairment (VCI), a complication of hypertension. The involvement of antioxidants and inflammatory biomarkers in the progression of hypertension to VCI is controversial and is investigated in this study. Methods: A total of 216 normoglycaemic individuals (aged 40-75 years) were enrolled into this case control study by systematic sampling method. They consisted of 81 Newly Diagnosed Hypertensives (NDH) without cognitive impairment, 69 Newly Diagnosed Hypertensives with Cognitive Impairment (NDHCI) attending Medical Outpatient Clinic and 66 apparently healthy individuals without hypertension or cognitive impairment (Controls), who were members of staff of University College Hospital, Ibadan.  Socio-demographic indices and lifestyle were obtained through a semi-structured questionnaire while Systolic and Diastolic tg6bn Blood Pressure (SBP and DBP, respectively) were obtained using standard methods. Neuropsychological assessment based on Cognitive Score (CS) was performed using Community Screening Instrument for Dementia. Antioxidants [Glutathione (GSH), Catalase (CAT) and Superoxide Dismutase (SOD)] and inflammatory biomarkers [Interleukin-6 (IL-6), High sensitivity C - reactive protein (hs-CRP)] in serum were estimated by ELISA. Data were analysed using Statistical Package for Social Sciences (SPSS) software 17.0 version. Analysis of variance (ANOVA) and Post Hoc test were used for comparison of variables while Chi square test was used to find associations between variables. Data analysed were significant at p<0.05.   Results: The inflammatory biomarkers hs-CRP (0.14±0.01; 0.12±0.01 versus 0.11±0.01 mg/L; p<0.001) and IL-6 (301.62±17.61; 115.60±16.01 versus 51.41±1.60 ng/mL; p<0.001) were significantly higher in NDHCI and NDH relative to control, respectively. Significant decreases in mean activities of catalase (81.71±1.01; 285.10±5.51 versus 403.00±17.31 ng/mL; p<0.001), SOD (5.04±0.97; 9.67±0.70 versus 12.02±0.53 ng/mL; p<0.007), GSH (7.02±0.89, 8.91±0.90; 20.5±1.31μg/mL; p<0.001) and cognitive scores (3.51±0.41; 18.81±0.50 against 28.71±0.20; p<0.001) were found in NDHCI compared with NDH and control, respectively. Conclusion: Increased oxidative stress and inflammatory processes may underlie the progression of hypertension to cognitive impairment.