Increasing orthostatic stress impairs neurocognitive functioning in Chronic Fatigue Syndrome with Postural Tachycardia Syndrome – Source: Clinical Science, Sep 15, 2011

[Note: POTS is a dysfunction in automatic adjustment to change in body position, especially on rising from prone to upright position. This causes an abnormally large increase in heart rate (tachycardia) as the body attempts to sustain adequate blood pressure, blood flow to brain, and thus consciousness.]

Chronic Fatigue Syndrome (CFS) is commonly co-morbid with Postural Tachycardia Syndrome (POTS).

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 cerebral blood flow velocity (CBFV). 16 CFS/POTS and 20 control subjects underwent graded tilt table testing (at 0, 15, 30, 45, 60, and 75 degrees) with continuous cardiovascular, cerebrovascular, and respiratory monitoring and neurocognitive testing using a N-back task at each angle.

The N-back task tests working memory, concentration, attention, and information processing. The N-back imposes increasing cognitive challenge with escalating (0, 1, 2, 3, and 4-back) difficulty levels.

• Subject dropout due to orthostatic presyncope [feeling faint] at each angle was similar between groups.

• There were no N-back accuracy or reaction time differences between groups while supine.

• CFS/POTS subjects responded less correctly during the N-back and had greater normalized reaction time at 45, 60, and 75 degrees.

• Further, at 75 degrees, CFS/POTS subjects responded less correctly and had greater normalized reaction time than controls during the 2, 3, and 4 back tests.

• Changes in cerebral blood flow velocity (CBFV) were not different between the groups and were not associated with N-back scores.

Thus, we concluded 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 cerebral blood flow velocity (CBFV).

Individuals with CFS/POTS should be aware that orthostatic stress may impair their neurocognitive abilities.

[Note: This team at New York Medical College’s Center for Pediatric Hypotension is running studies on POTS, CFS-POTS and IBS-POTS. The findings in this report are likely part of their study of “Vascular dysfunction in the chronic fatigue syndrome.” See also a recent report by another research team – “POTS symptoms generally more severe in CFS Patients, Vanderbilt finds”]

Source: Clinical Science (London), Sep 15, 2011. PMID: 21919887, by Ocon AJ, Messer Z, Medow M, Stewart J. Center for Pediatric Hypotension, New York Medical College, Hawthorne, New York, USA. [Email:]

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