ABNORMAL DIPPING PATTERN OF NOCTURNAL BLOOD PRESSURE AS A PREDICTOR OF COGNITIVE IMPAIRMENT AND/OR DEMENTIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract

Objective: Impact of abnormal nocturnal blood pressure (BP) dipping pattern on cognitive impairment and/or dementia is uncertain. The aim is to review the association between abnormal nocturnal BP dipping patterns (extreme dipping, non-dipping, or reverse dipping) and cognitive impairment and/or dementia in adults. Design and method: PubMed, MEDLINE, and EMBASE databases were systematically searched. Primary outcome was pooled odds ratios for cognitive impairment/dementia between normal and abnormal dipping patterns. Secondary outcomes were pooled mean Mini-Mental State Exam score among normal and abnormal dipping patterns, and pooled mean nocturnal dipping percentage among study participants with normal and low cognitive function. Results: When compared to normal dippers, reverse dippers have the strongest association with cognitive impairment/dementia (OR 5.56, 95%-CI 2.39–13.0, p = 0.0016) followed by non-dippers (OR 2.49, 95%-CI 1.39–4.45, p = 0.006). Association between extreme dippers and cognitive impairment/dementia was not statistically significant (OR 2.70 (95%-CI 0.80–9.12, p = 0.0904). The pooled mean Mini-Mental State Exam score among the non-dippers (26.8, 95%-CI 20.2 – 33.5) were lower than the normal dippers (27.4, 95%-CI 23.1–31.6). The standardized mean difference between the two groups was not significant (SMD -0.0694, 95%-CI -0.4998–0.361, p = 0.677). The pooled mean nocturnal dipping percentage among study participants with low cognitive function was (8.24%, 95%-CI 5.21–11.3) less than study participants with normal cognitive function (11.5%, 95%-CI 8.83–14.1). Similarly, the standard mean difference of mean nocturnal dipping percentage between the two groups was not significant (SMD -0.934, 95%-CI -2.053–0.186, p = 0.0906). Conclusions: Abnormal nocturnal dipping pattern may be a risk factor for cognitive impairment/dementia. Multiple included studies with cross-sectional data sets precludes drawing valid causal inference between dipping pattern and cognitive impairment.