.abstract
Postural Neurocognitive and Neuronal Activated Cerebral Blood Flow
Deficits in Young Chronic Fatigue Syndrome Patients with Postural
Tachycardia Syndrome
Julian M. Stewart*, Marvin S. Medow, Zachary R Messer, Ila Leigh
Baugham, Courtney Terilli, and Anthony J. Ocon
* New York Medical College julian_stewart@nymc.edu
Submitted 18 October 2011. Revision received 9 December 2011. Accepted
9 December 2011.
Abstract
Neurocognition is impaired in Chronic Fatigue Syndrome (CFS). We
propose that impairment relates to postural cerebral hemodynamics. 25
CFS and 20 control subjects underwent incremental upright tilt at 0=B0,
15=B0, 30=B0, 45=B0, 60=B0, and 75=B0 with continuous measurement of arteri=
al
blood pressure and cerebral blood flow velocity (CBFv). We used an
N-back task with N ranging from 0 to 4 (increased N=3D increased task
difficulty) to test working memory and information processing. We
measured N-back outcomes by the number of correct answers and by
reaction time. We measured CBFv, critical closing pressure (CCP), and
CBFv altered by neuronal activity (activated CBFv) during each N and
every tilt angle using transcranial Doppler ultrasound. N-Back outcome
in controls decreased with N but was independent of tilt angle. N-Back
outcome in CFS decreased with N but deteriorated as orthostasis
progressed. Absolute mean CBFv was slightly less than control in CFS
at each angle. Activated CBFv in controls was independent of tilt
angle and increased with N. In contrast, activated CBFv averaged 0 in
CFS, decreased with angle and was less than control. CCP was increased
in CFS suggesting increased vasomotor tone and decreased metabolic
control of CBFv. CCP did not change with orthostasis in CFS, but
decreased monotonically in control subjects, consistent with
vasodilation as compensation for the orthostatic reduction of cerebral
perfusion pressure. Increasing orthostatic stress impairs
neurocognition in CFS. CBFv activation, normally tightly linked to
cognitive neuronal activity, is unrelated to cognitive performance in
CFS; increased CCP and vasomotor tone may indicate uncoupling of the
neurovascular unit during orthostasis.
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