The objective of this study was to assess cognitive performance in older adults treated and controlled for blood pressure (BP) when compared to untreated normotensive subjects, and to determine whether blood pressure still correlates with poorer cognitive performances.Design and Method:
Forty-eight older adults aged between 65 and 85 years were recruited in the community and divided into two groups: normotensive (n = 26) and controlled hypertensive (n = 22). Each participant underwent a neuropsychological assessment that targeted memory, attention, language and executive functions. Ambulatory blood pressure monitoring (24 hours) as well as a blood test (Na+, K+, Ca2+, blood creatinine, glucose, triglycerides, thyroid function) were performed. One-way ANOVAs were conducted on each neuropsychological measure with group (normotensive vs. hypertensive) as a between-subject factor. Pearson correlations were also performed to examine the relationship between blood pressure parameters and cognitive performance.Results:
Results from ANOVAs revealed a significant difference between groups on response times in the switching condition of the Colour-Word Interference Test (CWIT), with controlled hypertensive patients performing worse than their normotensive counterparts. The analysis also demonstrated significant positive correlations (p < 0.05) between the percentage of systolic blood pressure (SBP) day values over 135 mmHg (% SBP day > 135 mmHg), and a number of conditions like, the switching cost from CWIT, and the Trail making Test Part B (TMTB). The switching conditions (e.g., TMTB), as well as the switching cost (difference in the reaction time between repetitive, and switching tasks), both assess cognitive flexibility, which is an executive function that relies heavily on prefrontal lobe integrity. Incidentally, these mechanisms have been reported as good predictors of cognitive decline and dementia in older adults.Conclusions:
There is a strong correlation between the % SBP day > 135 mmHg, and poor executive functioning, reinforcing the hypothesis that the BP threshold should be decreased to protect the brain of hypertensive subjects.