Very-low-frequency oscillations of cerebral hemodynamics and blood pressure are affected by aging and cognitive load

abstract Article history:Accepted 26 April 2013Available online xxxxKeywords:BOLDCerebral autoregulationNear infrared spectroscopySpontaneous oscillationsVasomotionWorking memory Spontaneousslowoscillationsoccurincerebralhemodynamicsandbloodpressure(BP),andmayreflectneuro-genic,metabolicormyogeniccontrolofthe cerebralvasculature.Agingisaccompanied bya degeneration of thevascularsystem,whichmayhaveconsequencesforregionalcerebralbloodflowandcognitiveperformance.ThisdegenerationmaybereflectedinareductionofspontaneousslowoscillationsofcerebralhemodynamicsandBP.Therefore, we aimed to establish the dependency of slow oscillations of cerebral hemodynamics and BP on thefactors age and cognitive load, by using functional near-infrared spectroscopy (fNIRS). Fourteen healthy young(23–32 years)and14healthyolderadults(64–78 years)performedaverbaln-backworking-memorytask.Ox-ygenated and deoxygenated hemoglobin concentration changes were registered by two fNIRS channels locatedover left and right prefrontal cortex. BP was measured in the finger by photoplethysmography. We found thatvery-low-frequencyoscillations(0.02–0.07 Hz)andlow-frequency oscillations (0.07–0.2 Hz)ofcerebralhemo-dynamics and BP were reduced in the older adults compared to the young during task performance. In youngadults, very-low-frequency oscillations of cerebral hemodynamics and BP reduced with increased cognitiveload. Cognitive load did not affect low-frequency oscillations of the cerebral hemodynamics and BP. Transferfunction analysis indicated that the relationship between BP and cerebral hemodynamic oscillations does notchange under influence of age and cognitive load. Our results suggest aging-related changes in the microvascu-laturesuchasdeclinedspontaneousactivityinmicrovascularsmoothmusclecellsandvesselstiffness.Moreover,our results indicate that inaddition tolocalvasoregulatoryprocesses, systemic processesalsoinfluencecerebralhemodynamicsignals.ItisthereforecrucialtotakethefactorsageandBPintoconsiderationfortheanalysisandinterpretation of hemodynamic neuroimaging data.© 2013 Elsevier Inc. All rights reserved.