*For medical professionals only
Middle-aged hypertension is associated with an increased risk of dementia in about 60 percent.
However, this association disappears in the elderly population, and few previous studies have found that high blood pressure is associated with an increased risk of dementia.
Some studies have reported a U-shaped association between blood pressure and dementia risk in older patients, and both hypertension and hypotension indicate an increased risk of dementia. However, there are currently few clinical studies of this U-shape association, and increased mortality in patients with hypertension may be a factor in the decline in the incidence of dementia. Understanding this U-shaped association with age and comorbidities, as well as the optimal systolic blood pressure (SBP) to minimize the risk of Alzheimer's disease, is critical for future designs of the best individualized blood pressure management trials in old age.
Recently, the journal JAMA Internal Medicine published a clinical study that used data from individual participants, combined with data from multiple population cohorts, to assess whether there was a U-shaped association between systolic blood pressure and dementia risk, and whether age and comorbidities played a role in this association. Let's take a look!
Research design
Using individual participation data, the cohort study analyzed seven prospective, observational, population-based cohort studies designed to assess dementia events in older adults.
These studies were initiated in Europe and the United States between 1987 and 2006. Enrolled patients had no prior diagnosis of dementia, had data on systolic and/or diastolic blood pressure at baseline, and developed dementia during follow-up.
Key endpoints of the study included:
All-cause dementia (defined using the Diagnostic and Statistical Manual of Mental Disorders [Third Revised Edition] or the Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition] and determined in follow-up measurements or clinical practice);
Covariates include:
Baseline antihypertensive drug use, sex, education level, body mass index, smoking status, diabetes mellitus, stroke history, history of myocardial infarction, and history of multipharmacy.
Use the Cox proportional risk regression model and explore nonlinear associations using natural curves.
Research results
The study analyzed data from seven cohort studies enrolling a total of 17,286 patients, of whom 10,393 (60.1%) were women and had a mean baseline age (SD) of 74.5 (7.3) years.
Overall, individuals with higher systolic blood pressure had a lower risk of developing dementia, with a systolic blood pressure of about 185 mmHg (95% CI, 161-230 mmHg; P = 0.001) having the lowest risk.
Baseline systolic blood pressure (SBP) is associated with dementia, mortality, and risk of dementia and death syndrome
Stratified by overlapping 10-year baseline age groups, the lowest risk of dementia was observed at lower systolic blood pressure levels in older adults over 75 years: 158 [95% CI 152-178] mmHg -170 [95% CI 160-260] mmHg.
In terms of mortality, there was a clear U-shaped relationship between systolic blood pressure and dementia risk, with the lowest risk of dementia at 160 mmHg (95% CI, 154-181 mmHg; P
This U-shaped association is distributed across all age groups
60-70 years of age group: lowest risk of dementia at systolic blood pressure of 134 mmHg (95% CI 102-149 mmHg; P = 0.03);
Age group 70-95 years: systolic blood pressure increased to 155 mmHg (95% CI 150-166 mmHg;P
Correlation of baseline systolic blood pressure (SBP) with a combined risk of dementia, death, dementia, and death
Correlation of systolic blood pressure with risk of a composite endpoint of dementia and death
The combined risk curve for dementia and death is very similar to the mortality curve. The relationship between diastolic pressure and dementia risk is broadly similar, but less pronounced.
Conclusions of the study
This cohort study found that older adults with higher levels of systolic blood pressure had a lower risk of dementia.
In older people >75 years of age, there is a more pronounced U-shaped association between systolic blood pressure levels and dementia risk, but these associations cannot be explained by changes in the risk of death associated with systolic blood pressure.
These findings suggest that life expectancy and health may need to be taken into account in future targeted blood pressure management trials in older populations.
Highlights to review
Research question: Is the relationship between systolic blood pressure and dementia U-shaped, and do age and comorbidities play a role in this relationship?
Findings: In this cohort study of 17,286 participants from seven studies, higher systolic blood pressure was associated with a lower risk of dementia in older adults, and the U-shaped relationship occurred only in the oldest age group. These associations are not attributed to longer survival with lower systolic blood pressure.
Implications: These findings suggest that the lowest risk of dementia associated with systolic blood pressure levels may vary between age groups, so when further trials are needed, individualized blood pressure targets that take into account an individual's life expectancy and health status should be developed.
source:
Association of Systolic Blood Pressure With Dementia Risk and the Role of Age, U-Shaped Associations, and Mortality. JAMA Intern Med. 2021. doi: 10.1001/jamainternmed.2021.7009.