Cerebral hemodynamics in aging: the interplay between blood pressure, cerebral perfusion, and dementia.

Abstract

Advances in measurement techniques have made it possible to study dynamic changes in brain blood flow. Transcranial Doppler ultrasonography measures changes in cerebral blood flow-velocity in the larger cerebral arteries (e.g. the middle cerebral artery). Near infrared spectroscopy records changes in brain cortical tissue concentrations of hemoglobin. These techniques are non-invasive, and can be performed with the subject in supine, sitting or standing position. Together with photoplethysmography, which measures arterial blood pressure at the finger, these methods provide detailed information on beat-to-beat changes in cerebral hemodynamics. In this thesis, these techniques have been further explored, with specific attention for their potential use in elderly subjects. First, we have considered that measurements of cerebral perfusion, complimenting measurements of blood pressure, will provide valuable insight in disorders of blood pressure regulation. Second, we have proposed that measurements of blood pressure, cerebral blood flow, and their interaction, are important in dementia research.