Increasing orthostatic stress impairs neurocognitive functioning in chronic fatigue syndrome with postural tachycardia syndrome.Alas, the sample size is a bit smallish…
Ocon AJ, Messer ZR, Medow MS, Stewart JM.
CFS (chronic fatigue syndrome) is commonly co-morbid with POTS (postural tachycardia syndrome).
Individuals with CFS/POTS experience unrelenting fatigue, tachycardia during orthostatic stress and ill-defined neurocognitive impairment, often described as 'mental fog'.
We hypothesized that orthostatic stress causes neurocognitive impairment in CFS/POTS related to decreased CBFV (cerebral blood flow velocity).
A total of 16 CFS/POTS and 20 control subjects underwent graded tilt table testing (at 0, 15, 30, 45, 60 and 75°) with continuous cardiovascular, cerebrovascular, and respiratory monitoring and neurocognitive testing using an n-back task at each angle.
The n-back task tests working memory, concentration, attention and information processing.
The n-back task imposes increasing cognitive challenge with escalating (0-, 1-, 2-, 3- and 4-back) difficulty levels.
Subject dropout due to orthostatic presyncope at each angle was similar between groups.
There were no n-back accuracy or RT (reaction time) differences between groups while supine.
CFS/POTS subjects responded less correctly during the n-back task test and had greater nRT (normalized RT) at 45, 60 and 75°.
Furthermore, at 75° CFS/POTS subjects responded less correctly and had greater nRT than controls during the 2-, 3- and 4-back tests.
Changes in CBFV (cerebral blood flow velocity) were not different between the groups and were not associated with n-back task test scores.
Thus we conclude that increasing orthostatic stress combined with a cognitive challenge impairs the neurocognitive abilities of working memory, accuracy and information processing in CFS/POTS, but that this is not related to changes in CBFV.
Individuals with CFS/POTS should be aware that orthostatic stress may impair their neurocognitive abilities.