Abstract
BACKGROUND: The objective of this systematic review and meta-analysis is to investigate whether nocturnal blood pressure fall, expressed by dipping patterns according to 24 h ambulatory blood pressure monitoring (ABPM), is associated with abnormal cognitive function (cognitive impairment or dementia). METHODS: We systematically searched PubMed, Embase, and Cochrane databases to identify original articles through December 2022. We included any study with at least ten participants reporting on all-cause dementia or cognitive impairment incidence (primary outcome) or validated cognitive tests (secondary outcome) among ABPM patterns. We assessed risk of bias using Newcastle-Ottawa Quality Assessment Scale. We pooled odds ratios (OR) and standardized mean differences (SMD) using random-effect models for primary and secondary outcome, respectively. RESULTS: In the qualitative synthesis, 28 studies examining 7595 patients were included. The pooled analysis of 18 studies showed that dippers had a 51% [OR 0.49(0.35-0.69)] lower risk of abnormal cognitive function and a 63% [OR 0.37(0.23-0.61)] lower risk of dementia alone, compared to non-dippers. Reverse dippers presented an up to sixfold higher risk [OR 6.06(3.15-11.64)] of abnormal cognitive function compared to dippers and an almost twofold higher risk [OR 1.81(1.26-2.6)] compared to non-dippers. Reverse dippers performed worse in global function neuropsychological tests compared with both dippers [SMD - 0.66(- 0.93 to - 0.39)] and non-dippers [SMD - 0.35(- 0.53 to - 0.16)]. CONCLUSION: Dysregulation of the normal circadian BP rhythm, specifically non-dipping and reverse dipping is associated with abnormal cognitive function. Further studies are required to determine potential underlying mechanisms and possible prognostic or therapeutic implications. PROTOCOL REGISTRATION: PROSPERO database (ID: CRD42022310384).