Endothelial dysfunction is a nearly universal complement to advancing age, manifest by a high prevalence of hypertension, atherosclerosis, and cardiovascular disease. Aging is also associated with changes in cerebral blood flow (CBF) regulation which may threaten cerebral perfusion and ultimately affect activities of daily living, resulting in functional disabilities as well as impaired cognition. Underlying all of these conditions lies the damaged blood vessel with a dysfunctional endothelium. Potential corrective therapies are unknown. This research, aimed broadly at studying the vascular benefits of flavanol-rich cocoa in two separate circulations, is directly related to the missions of both the NHLBI, in examining a potential prevention and treatment for cardiac and cerebrovascular disease, and of the NCCAM, by exploring a botanically-derived biological agent in the context of rigorous science. Consumption of flavonoid-rich beverages has been associated with a reduction in coronary events;our hypothesis credits their flavonoid content. Cocoa can contain extraordinary amounts of the flavonoid subset flavanols, shown to activate nitric oxide (NO) synthase. In the periphery, we showed that cocoa induced vasodilation, improving endothelial function in healthy people. Through infusion of the specific NO synthase inhibitor L-NAME, we demonstrated that the mechanism is NO- dependent. In a study of healthy elderly, we documented a rise in cerebral blood flow -- measured by transcranial Doppler -- following two weeks of flavanol-rich cocoa. We propose physiologic studies to determine the mechanism underlying cerebral blood flow responsiveness and whether it, too, is NO- dependent. We will also study brain blood flow by MRI, including regional studies and measures of flow in gray and white matter, anticipating specific increases with flavanol-rich cocoa. We will further examine the two methodologies, MRI and ultrasound, for concordance in measuring cerebral blood flow. Functional TCD responses will assess potential enhancement of neurovascular coupling. The trials will involve ingestion of a quality-controlled flavanol-rich cocoa product and mimetic as control, as well as parallel studies in the peripheral circulation. Dr. Fisher will continue her novel work as an independent clinical investigator in the area of cardio- and cerebrovascular disease, studying treatments of endothelial dysfunction that are innovative, intriguing and broadly applicable. Therapeutic interventions aimed at restoring vascular endothelial function, especially when derived from a naturally occurring biologically active agent, hold tremendous clinical promise.

Public Health Relevance

Endothelial dysfunction is a nearly universal complement to advancing age, underlying hypertension, cardiovascular disease and frequent cognitive decline. This research examines the mechanisms by which flavanol-rich cocoa increases cerebral blood flow. Ultimately these data might lay the foundation for a trial in the prevention of cognitive decline.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Clinical and Integrative Cardiovascular Sciences Study Section (CICS)
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Reid, Diane M
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Brigham and Women's Hospital
United States
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Beckman, Joshua A; Hurwitz, Shelley; Fisher, Naomi D L (2018) Arginine impairs endothelial and executive function in older subjects with cardiovascular risk. J Am Soc Hypertens 12:723-731
Purkayastha, Sushmita; Fadar, Otite; Mehregan, Aujan et al. (2014) Impaired cerebrovascular hemodynamics are associated with cerebral white matter damage. J Cereb Blood Flow Metab 34:228-34
Sorond, Farzaneh A; Hurwitz, Shelley; Salat, David H et al. (2013) Neurovascular coupling, cerebral white matter integrity, and response to cocoa in older people. Neurology 81:904-9
Fisher, Naomi D L; Hurwitz, Shelley; Hollenberg, Norman K (2012) Habitual flavonoid intake and endothelial function in healthy humans. J Am Coll Nutr 31:275-9
Sorond, Farzaneh A; Hollenberg, Norman K; Panych, Lawrence P et al. (2010) Brain blood flow and velocity: correlations between magnetic resonance imaging and transcranial Doppler sonography. J Ultrasound Med 29:1017-22
Hollenberg, Norman K; Fisher, Naomi D L; McCullough, Marjorie L (2009) Flavanols, the Kuna, cocoa consumption, and nitric oxide. J Am Soc Hypertens 3:105-12