Blood Pressure and Accelerated Brain Aging

With the constant stresses endured in everyday life, it is no wonder society’s blood pressures are shooting through the roof as soon as the morning alarm rings. In the US alone, an estimated 50 million individuals are affected by increased blood pressure, 62% of which are associated with attributable risk factor for cerebrovascular disease. Despite these concerning statistics, less than 60% of identified individuals receive treatment for their hypertension and only about a third of the population achieve adequate control of blood pressure. Now, new research published by Charles DeCarli in Lancet Neurology aids in the push towards greater awareness of blood pressure levels even amongst the healthy middle-aged population. DeCarli and his team found similar accelerated brain aging images in both young middle-aged people with high blood pressure compared to those whose blood pressure levels would not normally warrant the need for clinical intervention.

In the study, DeCarli and colleagues examined data collected from 579 individuals taking part in the Framingham Heart Study, a longitudinal investigation initiated over 60 years ago to examine cardiovascular health of people living in Framingham, Massachusetts. For the purposes of the current research, participants were mostly in their late 30s during the initial data collection phase in 2009. Upon entry into the study, participants had their blood pressure taken and were assigned to one of three groups according to the results: normal blood pressure, prehypertensive, or high blood pressure. Next, they underwent magnetic resonance imaging (MRI) brain scans that measured any white matter injury and gray matter atrophy (fractional anisotropy, white-matter hyperintensities). When these brain imaging measurements were combined, a global measure was produced that allowed for the comparison of brain health among different blood pressure groups.

Surprisingly, the researchers found that the brains of 30-year-olds with high blood pressure looked similar to the brains of people in their 40s who had normal blood pressure. They summarized that systolic blood pressure was associated with injury to white matter microstructure and regional grey matter in healthy young adults. Furthermore, injury worsened continuously as blood pressure increased and was significantly different between normotensive and prehypertensive subjects in some anatomical regions. Most importantly, these anatomical differences that were exhibited in subjects at fairly young ages were similar to the abnormal distributions seen within high blood pressure subjects later in life. Although a biological mechanism for how high blood pressure may cause increased brain aging was not proposed, the authors did suggest that blood pressure can lead to arterial stiffness which impedes blood flow and thus, reduce the supply of oxygen and essential nutrients to the receiving axons. In support of this proposal, arterial stiffness has been associated with cognitive impairment in elderly individuals in past research studies.

Although further research is required before any definite conclusions can be drawn, the current research findings do extend to those of earlier studies that indicate white-matter injury to begin before the age of 50 years old. The authors concluded that their “results emphasizes the need for optimum control of blood pressure, which is neither routinely achieved nor subject to testing in many randomized controlled clinical trials”. In the meantime, we can continue to increase our awareness regarding this topic, stressing the importance for regular monitoring for adverse blood pressure levels in order to promote healthy brain aging.

References

Chobanian, A., Bakris, G., Black, H., Cushman, W., Green, L., Izzo, J., Jones, D., Materson, B., Oparil, S., Wright, J., & Roccella, E. (2003). The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report JAMA: The Journal of the American Medical Association, 289 (19), 2560-2571 DOI: 10.1001/jama.289.19.2560

Hanon O, Haulon S, Lenoir H, Seux ML, Rigaud AS, Safar M, Girerd X, & Forette F (2005). Relationship between arterial stiffness and cognitive function in elderly subjects with complaints of memory loss. Stroke; a journal of cerebral circulation, 36 (10), 2193-7 PMID: 16151027

Maillard P, Seshadri S, Beiser A, Himali JJ, Au R, Fletcher E, Carmichael O, Wolf PA, & Decarli C (2012). Effects of systolic blood pressure on white-matter integrity in young adults in the Framingham Heart Study: a cross-sectional study. Lancet neurology, 11 (12), 1039-47 PMID: 23122892

Yoshita M, Fletcher E, Harvey D, Ortega M, Martinez O, Mungas DM, Reed BR, & DeCarli CS (2006). Extent and distribution of white matter hyperintensities in normal aging, MCI, and AD. Neurology, 67 (12), 2192-8 PMID: 17190943

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