High BP variability may increase lifetime dementia risk in late life but not in midlife

In a groundbreaking study researchers shed new light on the intricate relationship between blood pressure variability (BPV) and the risk of developing dementia. The study, based on data from the Adult Changes in Thought (ACT) study, a long-term investigation into cognitive health, has unveiled an intriguing pattern where the researchers found that high blood pressure variability increased lifetime dementia risk in late life but not in middle life.

The study was published in the journal JAMA Network Open. 

This cohort study, based on the ongoing Adult Changes in Thought (ACT) study, examined participants aged 65 or older, living in the community without dementia. It analyzed data from those with brain autopsy information and midlife to late-life blood pressure records. Cognitive assessments were performed biennially from 1994 to November 2019, with data analysis spanning from March 2020 to September 2023. The study assessed blood pressure variability at ages 60, 70, 80, and 90, calculated using the coefficient of variation of yearly systolic blood pressure measurements. The main outcome measured was all-cause dementia, adjudicated by a multidisciplinary committee.

Key Findings: 

• A total of 820 participants, with a mean age at enrollment of 77.0 years, were included, of which 476 (58.0%) were females.
• The study encompassed an average of 28.4 yearly systolic blood pressure (SBP) measurements over 31.5 years.
• The mean follow-up time was 32.2 years, accounting for 27,885 person-years from midlife to death.
• Out of the participants, 372 (45.4%) developed dementia.
• The number of participants eligible for analysis ranged from 280 at age 90 to 702 at age 70.
• Notably, elevated blood pressure variability (BPV) was not linked to an increased risk of dementia at ages 60, 70, or 80.
• However, at age 90, BPV was associated with a 35% higher dementia risk (hazard ratio [HR], 1.35; 95% CI, 1.02-1.79).
• Meta-regression of HRs calculated for each age group (60-90 years) revealed that the connection between high BPV and increased dementia risk was primarily observable at older ages.
• Meanwhile, the relationship between SBP and dementia shifted linearly from being incrementally associated with younger ages to inversely associated with older ages.

In conclusion, this cohort study, drawing on the ACT study's extensive data, provides a nuanced view of the relationship between BPV, SBP, and dementia risk. It highlights the importance of considering age-specific factors when developing strategies to prevent and treat dementia, offering hope for more effective interventions as we gain a deeper understanding of the complex dynamics at play in late-life cognitive health.

Further reading: den Brok MGHE, van Dalen JW, Marcum ZA, et al. Year-by-Year Blood Pressure Variability From Midlife to Death and Lifetime Dementia Risk. JAMA Netw Open. 2023;6(10):e2340249. doi:10.1001/jamanetworkopen.2023.40249