October 10, 2017Open Access
Visit-to-Visit Blood Pressure Variability in Young Adulthood and Hippocampal Volume and Integrity at Middle Age
Key Result
Higher visit-to-visit systolic blood pressure variability in young adulthood was associated with lower midlife hippocampal volume (β=-0.006) and fractional anisotropy (β=-0.02; P<0.05).
Study Design
Type
Cohort (n=545)
Structured PICO
Does visit-to-visit blood pressure variability in young adulthood predict reductions in hippocampal volume and integrity in midlife?
P
Population
545 black and white adults, aged 18-30 years at baseline, followed for 25 years to assess the relationship between blood pressure variability and midlife hippocampal volume.
E
Exposure
Higher visit-to-visit blood pressure variability (assessed by SD BP and average real variability [ARV BP]) over 25 years
C
Comparator
Lower visit-to-visit blood pressure variability
O
Outcome
Hippocampal tissue volume standardized by intracranial volume (%) and integrity assessed by fractional anisotropy measured by 3-Tesla magnetic resonance imaging at the year-25 examinationsurrogate
Visit-to-visit blood pressure variability during young adulthood is associated with reduced hippocampal volume and integrity in midlife, independent of cumulative BP exposure.
Main Result
Effect estimate: Coefficient -0.006
p-value: p=<0.05
Abstract
The aims of this study are to assess the relationships of visit-to-visit blood pressure (BP) variability in young adulthood to hippocampal volume and integrity at middle age. We used data over 8 examinations spanning 25 years collected in the CARDIA study (Coronary Artery Risk Development in Young Adults) of black and white adults (age, 18–30 years) started in 1985 to 1986. Visit-to-visit BP variability was defined as by SD BP and average real variability (ARV BP , defined as the absolute differences of BP between successive BP measurements). Hippocampal tissue volume standardized by intracranial volume (%) and integrity assessed by fractional anisotropy were measured by 3-Tesla magnetic resonance imaging at the year-25 examination (n=545; mean age, 51 years; 54% women and 34% African Americans). Mean systolic BP (SBP)/diastolic BP levels were 110/69 mm Hg at year 0 (baseline), 117/73 mm Hg at year 25, and ARV SBP and SD SBP were 7.7 and 7.9 mm Hg, respectively. In multivariable-adjusted linear models, higher ARV SBP was associated with lower hippocampal volume (unstandardized regression coefficient standard error with 1-SD higher ARV SBP : −0.006 0.003), and higher SD SBP with lower hippocampal fractional anisotropy (−0.02 0.01; all P <0.05), independent of cumulative exposure to SBP during follow-up. Conversely, cumulative exposure to SBP and diastolic BP was not associated with hippocampal volume. There was no interaction by sex or race between ARV SBP or SD SBP with hippocampal volume or integrity. In conclusion, visit-to-visit BP variability during young adulthood may be useful in assessing the potential risk for reductions in hippocampal volume and integrity in midlife.