Hypertension and Neurocognitive impairment as measured by the Zambia Neurobehavioural test battery--A pilot study

Abstract

Hypertension has been reported as one of the most important etiologic factors in cardiovascular disease. Hypertension has serious social, physical and health consequences.The physical consequences of hypertension have been well researched. However the effect of hypertension on neurocognitive functioning has received less attention in research. Some studies (e. g Starr, Deary, Fox & Whalley (2006) have reported deficits in some domains of cognition, while others (e. g. Huang et al., 2009) have reported no significant findings on comparisons between hypertensives and normotensives. However the larger and more consistent ones (e. g Waldstein et al., 1996) have noted deficits in learning and memory, attention, abstract reasoning and executive functions. Hypertension affects the quality of life. Research into this area has revealed different results depending on the type of medication and the instruments being used to measure quality of life. This study aims at finding out the relationship between hypertension and neurocognitive function.The study was cross sectional in design, the sample consisted of 50 adult Zambians aged 40-65.21 hypertensives (mean age of 52.81 SD 6.047, mean education of 10.62 SD 2.674) 29 normotensives (mean age of50.48 SD 6.260, mean education of 11.45 SD 2.910). Out of 50, 15 were male and 35 were female. The recruitment was done in the clinics with the help of clinic staff. The neuropsychological domains measured in the present study were executive functioning, fluency, verbal episodic memory, visual episodic memory, motor dexterity, working memory, and speed of information processing. The measures used included: Blood pressure, neuromedical evaluation, neurocognitive assessment using the Zambia Neurobehavioral Test Battery, SF12 Health Survey ,Hypertension questionnaire.Data analysis: Independent sample t-test was used to determine if there were any statistically significant differences in neuropsychological test performance between hypertensives and normotensives on the seven ability domains of neuropsychological functioning measured. Chi square was calculated to see if there was a significant difference in the impairment index (Global Deficit Scores) between the two groups. Pearson’s correlation test was used to investigate the relationship between the side effect variable and quality of life. Results: There was no significant difference in neuropsychological test performance on all the seven ability domains measured. On Global Deficit Scores impairment index, Chi square showed more impairment in the hypertensive group; however this was not statistically significant. Pearson’s correlations test showed that at 0.05 sig. side effects correlated negatively with Physical functioning (r=0.593) and mental health (r=0.598) and at 0.01 sig. with vitality scale (r=0.6340 and social functioning (r=0.618) of the SF12 health survey domains. Conclusion: Quality of life seems to be more affected than neurocognitive functioning in the hypertensives in this study.