Increased late-life blood pressure (BP) changes may predict more brain infarcts, according to a recent study in Neurology.
“The overall hypothesis of the study was that late-life BP is associated with common brain pathology of aging, specifically cerebrovascular disease (infarcts) and neurodegeneration ([Alzheimer’s disease (AD)]),” wrote the authors, led by Zoe Arvanitakis, MD, medical director, Rush Memory Clinic, Rush Alzheimer’s Disease Center, and professor, Department of Neurological Services, Rush Medical College, Rush University Medical Center, Chicago, IL.
Little research has been done elucidating the relationship between late-life systolic blood pressure (SBP) or diastolic blood pressure (DBP) and the occurrence of brain infarcts or stroke. Furthermore, the research that has been done is unclear.
Although there are much diagnostic data on BP and cerebrovascular disease, few data exist regarding pathologically proven brain infarcts. Brain infarcts often go clinically undetected in the elderly, and small infarcts are often missed on neuroimaging.
In addition, few studies have examined the link between late-life BP and AD, another common illness of older age.
Despite the potential of emerging neuroimaging and biotechnological advances, direct assessment of cerebrovascular disease and AD pathology are integral to elucidate the link between BP and common conditions of the elderly, the authors stressed. Certain features of this relationship can be discovered using only neuropathological examination.
In this community-based cohort study, the researchers followed 1,288 individuals (65% women; mean age at death: 88.6 years) for a mean duration of 8 years. Mean SBP at baseline was 136 mmHg, and mean DBP level at baseline was 72 mmHg. When the researchers averaged these measures over the years of the study, the mean SBP and DBP levels were 134 mmHg and 71 mmHg, respectively.
They identified a mean decline of 0.1 mmHg per year in DBP. SBP declined by an average of 0.8 mmHg per year. Notably, the decline in BP was nonlinear, and 50% occurred in the 6 years preceding death.
Two-thirds of the participants exhibited hypertension during the course of the study, with 87% taking antihypertensive medications.
On autopsy, nearly one-half (48%) of participants experienced ≥ 1 chronic infarcts of any size or location; one-third had gross infarcts, one-third microinfarcts, and 15% had a mix of both. The team also found that most participants harbored some degree of AD pathology.
They employed regression analysis while controlling for demographic factors to analyze the associations of “average and decline in late-life SBP, and separately in DBP, with neuropathology.”
The researchers discovered that the odds of brain infarcts were higher for participants with a higher mean SBP. For instance, a participant with an SBP level of 1 SD above the mean (147 mmHg) had a 46% heightened probability of exhibiting ≥ 1 infarcts, as well as higher odds of gross infarct (46%) and microinfarct (36%).
Dr. Arvanitakis and colleagues also found that more rapidly decreasing SBP slope over time was associated with higher odds of one or more infarcts, and that mean DBP—but not slope—was associated with brain infarcts.
With respect to AD pathology, the researchers found an association between a higher mean SBP and increased tangles (P=0.038), but no association with plaques or other pathology (P > 0.06).
One limitation of this study was that researchers lacked data concerning midlife BP measures. They also did not have data on BP readings between BP yearly measurements, thus precluding assessment of shorter-term changes. Additionally, most participants were taking antihypertensive medications, thereby rendering BP relatively well controlled.
“Higher average late-life SBP and DBP, and independently a faster decline in SBP, are associated with increasing number of brain infarcts, including gross and microinfarcts,” concluded the authors. “We found some evidence for a relation of SBP with AD, specifically tangles. Both average and decline in BP are related to brain disease.”
This study was funded by grants from the National Institutes of Health.