Higher visit-to-visit blood pressure variability has been linked with impaired cognitive function in elderly patients who are at risk of cardiovascular disease, say researchers
The study
The European prospective cohort study included 5,461 participants with a mean age of 75.3 years who were at risk of cardiovascular disease. All participants were >70 years. Over an average period of 3.2 years, blood pressure was measured every three months. Visit-to-visit variability was defined as the standard deviation of blood pressure measurements between visits, with high variability defined as an SD of 16.3-64.4mmHg and low variability as 0.7-12.2mmHg. The four outcomes to measure cognitive function in patients were testing: selective attention, processing speed, and immediate and delayed memory. The Stroop colour and word tests were used to assess selective attention and reaction time. Cognitive speed was measured using the letter-digit coding test. The picture-word learning test was used to assess immediate and delayed memory.
The findings
Participants with higher visit-to-visit variability in systolic blood pressure had worse performance in all cognitive tests, compared with those with low variability. The mean differences between high and low variability groups were: attention -3.08 seconds, processing speed -1.16 digits coded, immediate memory -0. 27 pictures remembered, and delayed memory -0.30 pictures remembered. All associations were adjusted for average blood pressure and cardiovascular risk factors.
What this means for GPs
The researchers note that their findings ‘suggest that higher visit-to-visit variability in blood pressure is associated with worse cognitive performance in older people at high risk of cardiovascular disease’. They also mention that further studies should be undertaken to ‘determine whether reducing variability in blood pressure can decrease the risk of cognitive impairment in old age’.
BMJ 2013;347, online July 2013
