Cerebral blood flow modulations during antisaccade preparation in chronic hypotension

Abstract

In addition to symptoms including fatigue, dizziness, reduced drive, or mood disturbance, individuals with chronic low blood pressure (hypotension) frequently report cognitive complaints. While attentional deficits have been empirically confirmed, it is still unknown whether the impairments also encompass executive functions. This study investigated cerebral blood flow modulations in hypotension during a precued antisaccade/prosaccade task requiring the executive function of proactive inhibition in addition to preparatory attention. Using functional transcranial Doppler sonography, bilateral blood flow velocities in the middle cerebral arteries (MCA) were recorded in 39 hypotensive and 40 normotensive participants. In the task, a stimulus appeared left or right of a fixation point 5 s after a cuing stimulus; subjects had to move their gaze to the mirror image position of the stimulus (antisaccade) or toward it (prosaccade control condition). Video‐based eye tracking was used for ocular recording. A right dominant MCA blood flow increase arose during task preparation, which was smaller in hypotensive than normotensive participants. In addition, hypotensive participants exhibited lower peak velocity of the saccadic response. The extent of the reductions in blood flow and task performance in hypotension did not differ between antisaccade and prosaccade conditions. The smaller MCA flow increase may reflect reduced activity in the dorsolateral prefrontal and inferior parietal cortices during proactive inhibition and preparatory attention in hypotension. Given that group differences in blood flow and performance arose independent of task complexity and executive function load, hypotension may be characterized by basic attentional impairments rather than particular executive function deficits.

Experimental carotid baroreceptor stimulation reduces blood flow velocities in the anterior and middle cerebral arteries of healthy individuals

“…However, there is evidence challenging the dissociation between peripheral and cerebral hemodynamics [ 30 , 33 ]. For example, healthy subjects with chronically low blood pressure exhibited smaller increases in MCA blood flow velocities during cognitive activity than those with normal blood pressure [ 11 , 17 , 18 ]. Pharmacologically induced blood pressure enhancement led to increase of tonic MCA perfusion and stronger flow velocity responses during cognition [ 12 ].…”

The scalability of common paradigms for assessment of cognitive function: A functional transcranial Doppler study

“…To our knowledge, the role of the ‘central command’ during cognitive paradigms in fTCD studies has received very little attention in the human NVC literature [ 67 ]. Previous studies suggested that the preparatory process of blood flow adjustment involves alertness of attentional function [ 68 ], correlated with increasing CBF response before the onset of exercise that is likely governed by the ‘central command’ network [ 69 ]. Therefore, increased CBFV at the onset of all paradigms, independently of complexity or duration, was probably determined by the effects of ‘central command’ on the neurovascular unit.…”

“…BOLD) [ 10 , 78 , 79 ] and our paradigms. According to the ‘central command’ hypothesis, the lack of marked differences in CBFV responses with varying durations could be explained by the anticipatory response to cognitive demand in the attentional process [ 68 ], governing an upsurge of CBFV around 5s after onset stimulation, without further influence of the duration of stimulation on the NVC mechanism.…”