14 Dec Dementia Risk and Systolic Blood Pressure: A U-Shaped Association
MedicalResearch.com Interview with:
Jan Willem van Dalen, PhD
Department of Neurology
Donders Institute for Brain, Behaviour and Cognition
Radboud University Medical Centre Nijmegen
Department of Neurology
The Netherlands3Department of Public and Occupational Health
Amsterdam UMC, University of Amsterdam, Amsterdam
MedicalResearch.com: What is the background for this study?
Response: Although high systolic blood pressure in midlife has consistently been reported as a condition that increases the risk of developing dementia in old age, reports regarding this relationship in older people have been inconsistent. One potential reason for this, is that the relationship between systolic blood pressure and dementia in later life may be U-shaped, meaning that both individuals with low and with high systolic blood pressure are at increased incident dementia risk.
This study combined data from several longitudinal cohort studies specifically designed to study incident dementia in older people, to investigate whether these U-shaped relationships exist, and in which age ranges they appear. We included more than 16,500 people aged 60 and older, with over 2,700 incident dementia cases.
Also, we aimed to investigate whether these observational associations might be caused by confounding, differences in mortality, or result from opposite relationships between certain subgroups of individuals.
MedicalResearch.com: What should readers take away from your report?
Response: It seems that these U-shaped relationships do indeed develop with ageing, with older individuals with systolic blood pressures in the range of 160-170 mmHg having the lowest risk of developing dementia. Interestingly however, aged between 60 and 75, the risk of developing dementia seemed to be consistently lower for individuals with higher systolic blood pressure. There were no clear indications that these relationships could be explained by confounding, detrimental effects in specific sub groups of individuals, or differences in incident mortality. This suggests that in general, relatively high systolic blood pressure levels in individuals over the age of 65, indicate less dementia risk going forward. However, it is important to remember that these are all relationships from observational studies, impeding any inferences regarding causality.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: It is essential that we try to find out what might explain these observational relationships, and whether the relationship between low blood pressure and increased dementia risk is possibly causal in certain (sub groups) of older people. As long as these mechanisms remain unclear, doubts may continue to be raised about whether lowering blood pressure in older people is good for all, or that low values may be detrimental in certain groups of patients. The problem with the current clinical trial data being that they only represent a rather specific sub selection of older people who meet the inclusion criteria of these trials and are willing and able to participate. These may not include those individuals that are susceptible to adverse effects from low blood pressure living in the general population.
I do not have any disclosures to report.
van Dalen JW, Brayne C, Crane PK, et al. Association of Systolic Blood Pressure With Dementia Risk and the Role of Age, U-Shaped Associations, and Mortality. JAMA Intern Med. Published online December 13, 2021. doi:10.1001/jamainternmed.2021.7009
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