Direct electric stimulation to increase cerebrovascular function

Various conditions affecting the cerebral vasculature may lead to cumulative damage and thus deterioration of brain function, in what has been called vascular cognitive impairment (Gorelick et al., 2011). Consequently, it makes sense that an increase in glucose and oxygen produced by an increase in blood flow may augment brain function. Since its rediscovery some years ago transcranial direct electric stimulation (tDCS) has attracted interest as potential therapy for patients with neurological impairments. This opinion article aims to succinctly review themechanisms involved in neurogenic control of the cerebral blood flow (CBF) highlighting the potential of direct electrical stimulation targeting cerebral micro vessels to enhance brain function. With the highest oxygen consumption than any other organ in the body, the brain utilizes around 20% of the total resting oxygen, making it an organ highly dependent on blood supply (Hossmann, 1994). Moreover, a direct relationship between the development of neurodegenerative diseases and impairment of CBF has been postulated (Farkas and Luiten, 2001). The appropriate delivery of nutrients and oxygen to the brain tissue is regulated by mechanisms including cerebral autoregulation, vascular reactivity and neurovascular coupling. The autoregulatory properties of cerebral circulation make CBF independent of systemic blood pressure. Therefore, over a physiological range of pressure cerebral arteries relax when systemic pressure decreases and constrict when systemic pressure increases (Heistad and Kontos, 1983). Similarly, reactivity of the brain blood vessels to pH and CO2 has been suggested to link neuronal metabolic changes to cerebral blood flow.