Study links blood pressure variability with dementia and cognitive impairment
Australia: A recent study has found higher levels of mean systolic pressure, systolic BPV, diastolic BPV, and mean diastolic pressure to be associated with cognitive impairment and dementia. The study findings appear in Hypertension, the journal of the American Heart Association.
Previous studies have shown a link between blood pressure variability (BPV) with stroke and cerebrovascular disease, however, its association with cognition is ambiguous. Moreover, it is also not certain which BP-derived parameter (ie, variability or mean) is more significant in understanding vascular contributions to cognitive impairment. To study which parameter is more significant for the said factor, Phillip J. Tully, The University of Adelaide, Australia, and colleagues searched the online databases and performed a meta-analysis of studies that quantified the association between resting BPV with dementia or cognitive impairment in adults.
Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Meta-Analysis of Observational Studies in Epidemiology guideline, two authors independently reviewed all titles, abstracts, and full-texts and extracted data. Study quality was assessed using the (modified) Newcastle-Ottawa Scale.
A multilevel meta-analysis was used, which included effect sizes for both BPV and mean BP, with a combined endpoint of dementia or cognitive impairment as primary outcome. In the primary analysis, 54 effect sizes were extracted from 20 studies, with a total analytical sample of n=7 899 697.
Key findings include:
- Higher systolic BPV (odds ratio [OR], 1.25), mean systolic pressure (OR, 1.12), diastolic BPV (OR, 1.20 [95% CI, 1.12–1.29]), and mean diastolic pressure (OR, 1.16) were associated with dementia and cognitive impairment.
- A direct comparison showed that mean BP effect sizes were less strong than BPV effect sizes (OR, 0.92), indicating that the relative contribution of BPV exceeded that of mean BP.
- Methodological and statistical heterogeneity was high.
- Secondary analyses were less consistent as to whether BPV and mean BP were differentially associated with dementia subtypes and cognitive domains.
"The direct comparison revealed that mean BP impact sizes were weaker than blood pressure variability (BPV) effect sizes, indicating that the relative contribution of BPV exceeded that of mean BP," the researchers wrote. "The level of methodological and statistical heterogeneity was substantial. Secondary analyses were less consistent in determining whether BPV and mean BP were linked with dementia subtypes and cognitive domains differently."
Future studies are required to investigate BPV as a target for dementia prevention, they concluded.