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AlzRisk Risk Factor Literature Search Strategy and Results
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Risk Factor: Blood Pressure
  (BP, DBP, diastolic, diastolic blood pressure, hypertension, hypotension, pulse pressure, SBP, systolic, systolic blood pressure)
Risk Factor Type: Chronic disease, Metabolic
Current Understanding:
The tables below present inconsistent data on the relationship between blood pressure and AD and total dementia. There is a suggestion of an age-dependent relationship, i.e., hypertension may be harmful in midlife and protective in late-life. However, few studies have specifically considered the association between midlife blood pressure and AD, and it is possible that that bias (in particular reverse causation or selection bias) might account for any protective association in late-life. Further research is necessary and should focus on the impact of blood pressure in midlife, on potential modifying effect of anti-hypertensive drug use, and on quantifying the potential that selection bias or reverse causation might account for the observed associations. Despite the uncertainty regarding the relationship between blood pressure and risk of AD, the benefits of blood pressure control on cardiovascular risk are sufficient to justify current treatment standards. For a discussion of the putative mechanisms by which blood pressure may influence AD risk and commentary on interpreting the findings below in a broader context, please see the Discussion. A longer review and discussion can be found in the published review and meta-analysis, Power MC, Weuve J, Gagne JJ, McQueen MB, Viswanathan A, Blacker D. The association between blood pressure and incident Alzheimer disease: a systematic review and meta-analysis (Epidemiology 2011;22:646-659).
Last Search Completed: 01 November 2011 - Last content update released on 1 Nov 2012.

Risk Factor Overview


Summary

Original search (through 2010)

We conducted our original literature search in two phases. In the first phase, we identified eligible papers, published prior to 1 January 2010, by non-systematic review of several databases (MEDLINE, EMBASE, Web of Science, and Google Scholar), searches of citation lists from initially identified papers, consultation with experts, and hand searches of publications on well-known study cohorts. In the second phase, we conducted systematic searches in MEDLINE, EMBASE, CINAHL, and Web of Science for peer-reviewed articles, published prior to 1 January 2011, reporting on the association of blood pressure and/or hypertension with risk of Alzheimer’s disease (AD) incidence in cohort or nested case-control studies. The first phase identified 19 articles which met our inclusion criteria. Two of these articles evaluate overlapping samples, but as the overlap was minimal (<25%) we chose to include both.


In the second phase, our systematic search returned 4129 unique citations that, after excluding the 19 articles identified in Phase 1 and after title and abstract review, were narrowed down to 138 citations for full-text review. Two of these remaining articles fully met criteria for inclusion in our summary tables. Adding these to the 19 previously identified articles, a total of 21 articles were included this systematic review. Please see our methods section for more detail on our general systematic review methods



Update (through November 2011)

We updated the literature search to include manuscripts published through 11/1/2011 through systematic searches of MEDLINE, EMBASE, CINAHL, and Web of Science. Search terms were similar to those used through 2010 (described above), with a slightly expanded set of terms chosen to ensure that this systematic search correctly captured eligible articles known to be published during this period. Please note that this search overlaps somewhat with the original search, given that it was difficult to set date limits that did not overlap with previous searches in several of the databases used. The systematic search terms used in this update are provided below, minus the date limits used in each database. This search returned 884 articles, including duplicates, which were narrowed down to 19 for full-text review. Four additional papers qualified for inclusion in our summary tables, bringing the total number of articles included in the updated systematic review to 25.

Search & Review Flowchart
Search Strategy



Search Strategy Flowchart


Search Strategy


The search strategy described below corresponds to the search terms used in the November 2011 update, although we have omitted date limits, as these search terms are slightly more expansive than those used in the second phase of the original search. For search terms used in the original search, please refer to the published paper, which used the same literature search. In both cases, we queried four databases: MEDLINE (via PubMed), EMBASE, CINAHL, and Web of Science.


Search Strategy Table