Visit-to-Visit Variability in Blood Pressure May Be Linked to Faster Rate of Cognitive Decline

Higher long-term blood pressure (BP) visit-to-visit variability may be associated with a faster rate of cognitive decline among older adults, according to data published in Hypertension.

While midlife hypertension has been considered a risk factor for cognitive decline, researchers note that the association between late-life hypertension and cognitive decline remains unclear.

“In addition, randomized clinical trials have not shown a consistent effect of BP-lowering treatments for reducing the risk of cognitive decline or dementia,” they wrote.

A total of 976 adults had 3 or 4 visits with BP measurements in addition to cognitive screening tests during at least 2 visits. Researchers estimated cognitive decline after a mean follow-up time of 5.3 years.

Older age, higher urbanization index, lower education, less physical activity, history of stroke or diabetes, and antihypertensive medication use were all associated with higher visit-to-visit variability (expressed as standard deviation [SD]) of systolic blood pressure (SBP). Mean SBP was progressively higher with increased SD of SBP (r=0.33).

The global cognitive decline associated with the middle and highest tertiles was faster by –0.13 points per year (95% confidence interval [CI]: –0.33 to 0.07) and –0.26 points per year (95% CI: –0.45 to –0.06), respectively (P=.01), compared with the lowest tertile of SD of SBP. Even after adjustment for age, sex, and education, or further adjustment for urbanization index, smoking, physical activity, antihypertensive medication, and mean SBP, visit-to-visit variability of SBP remained associated with a faster decline of cognitive function.

However, researchers did not find a significant association between change in SBP (mean change between first and last visit: 8.4 mm Hg [SD: 21.5]) and global cognitive decline (tertile 3 vs tertile 1: beta= –0.13; 95% CI: –0.33 to 0.06; P=.09). Greater model variation and residual variation of SBP were both associated with a faster rate of cognitive decline.

“The associations between visit-to-visit variability in SBP and cognitive decline were not modified by age,” researchers noted. “For example, compared with the lowest tertile of SD of SBP, the unadjusted rate of global cognitive decline associated with the highest tertile was different by –0.18 points per year (95% CI: –0.42 to 0.07) among those aged 55 to 64 years and by –0.32 points per year (95% CI: –0.64 to –0.01) among those aged ≥65 years.”

However, age did significantly modify the association between diastolic blood pressure (DBP) variability and cognitive decline (P=.01). Therefore, all subsequent DBP analyses were stratified by either age 55 to 64 years and ≥65 years. The correlation between mean DBP and SD of DBP was r=0.14 in adults <64 years of age and r=0.09 in adults ≥65 years of age. The unadjusted annual rate of cognitive decline among adults aged <65 years was faster by –0.27 points (95% CI: –0.51 to –0.03) and –0.27 points (95% CI: –0.51 to –0.03) for the middle and highest tertiles of SD of DBP (P=.03).

“In this study, although benefits of lower variability in SBP were observed for the full sample, we found that the association between DBP variability and cognitive decline was stronger at younger ages,” researchers wrote. “We hypothesize that this may be because of fewer competing causes of cognitive disorders.”

They concluded, “Controlling BP instability could possibly be a strategy in preserving cognitive function among older adults, but intervention trials and more longitudinal studies are needed to confirm this finding.”

Reference

Qin B, Viera AJ, Munter P, et al. Visit-to-visit variability in blood pressure is related to late-life cognitive decline. Hypertension. 2016. doi: 10.1161/HYPERTENSIONAHA.116.07494.