Results from a study led by Radboud University Medical Center in the Netherlands shows frequent changes in blood pressure only increase dementia risk in people who are 90 years or older.
However, the findings showed that individuals between the age of 60 and 89 with high blood pressure variability did not have increased risk.
“Midlife hypertension is associated with higher dementia risk,” write Jan Willem van Dalen, a postdoctoral researcher at Radboud University Medical Center, and colleagues in JAMA Network Open.
“Blood pressure lowering may decrease dementia risk. However, the association between BP and dementia remains poorly understood. With older age, this association seems to dissipate or even reverse, and individuals with hypertension have lower dementia risk.”
To investigate the possibility that change in blood pressure may be a better dementia risk predictor than average systolic blood pressure, van Dalen and team analyzed data from an ongoing population-based prospective cohort study in the U.S. called the Adult Changes in Thought study.
Overall, 820 participants (58% female) were included in the study. The follow-up period from enrolment was 31 years, with 28 yearly blood pressure readings available. The average age at enrollment was 77 years and no participants had dementia at the beginning of the study.
Over the follow-up period, 372 participants developed dementia. Blood pressure measurements were made regularly and compared between visits for each participant to assess variability, taking into account increasing blood pressure with age.
The average systolic blood pressure increased gradually with age from 131 mmHg in 60-year-olds to 141 mmHg in those aged 90 years and older. Blood pressure variability was 9.31 in those aged 60 years and 11.22 in those aged 90 years.
In participants aged 60–69, 70–79, and 80–89 years of age, variation in blood pressure did not impact risk. However, at 90 years, a 1-standard deviation increase in blood pressure variability was linked with a 35% higher risk for dementia.
Notably, the link between systolic blood pressure level and dementia risk changed with increasing age. At age 60 years, a 1-standard deviation increase in systolic blood pressure increased dementia risk by 7%, whereas by the age of 70 years it had no impact on risk and by the age of 80 and 90 years it reduced risk of dementia by 10% and 18%, respectively.
“The finding in this study that midlife blood pressure variability did not affect lifetime dementia risk makes a causal, cumulative dose response association less likely,” conclude the authors.
“The body’s ability to maintain homeostasis may decrease with aging, making older age–related elevated blood pressure variability a marker of advanced biological age and thereby associated with dementia.”