A U-shaped Association Between Blood Pressure and Cognitive Impairment in Chinese Elderly.
Yue-Bin Lv, Peng-Fei Zhu, Zhao-Xue Yin and 11 others
PMID 28126139WHAT IT FOUND
In older Chinese adults, both low and high blood pressure were linked to more cognitive impairment.
Risk appeared lowest near 141 mm Hg systolic and 85 mm Hg diastolic. This is association, not proof that changing blood pressure prevents impairment.
Key findings
01Generalized additive and quadratic models showed U-shaped associations for systolic, diastolic and mean arterial pressure with cognitive impairment, while pulse pressure was not clear after adjustment.
02Below the systolic cut-point of 141 mm Hg, each 1 mm Hg lower systolic pressure was associated with 0.7% higher risk of cognitive impairment after full adjustment.
03Above the systolic cut-point of 141 mm Hg, each 1 mm Hg higher systolic pressure was associated with 1.2% greater risk.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The study measured blood pressure and cognitive test scores at the same time, so it cannot show which came first. Blood pressure was taken at one visit, and use of antihypertensive medicines was missing, so readings may not represent usual blood pressure. The sample was very old, with an average age of 87 years, and came from China, so results may not apply to younger or other populations. Weight loss, dietary change, psychological stress and oxidative stress were not measured, so they could help explain the association. No blood pressure treatment was tested, so the paper cannot say that lowering or raising blood pressure prevents or improves cognitive impairment.
Declared interests
None declared.
The easy way to misread this
Do not read the 141 mm Hg systolic and 85 mm Hg diastolic values as proven targets to prevent cognitive impairment. The study observed an association at one time and did not test whether changing blood pressure improves cognition.