Reduced Cardiac Vagal Modulation Impacts on Cognitive Performance in Chronic Fatigue Syndrome

Cognitive difficulties and autonomic dysfunction have been reported separately in patients with chronic fatigue syndrome (CFS). A role for heart rate variability (HRV) in cognitive flexibility has been demonstrated in healthy individuals, but this relationship has not as yet been examined in CFS. The objective of this study was to examine the relationship between HRV and cognitive performance in patients with CFS.

Patients with CFS showed no deficits in performance accuracy, but were significantly slower than healthy controls. CFS was further characterized by low and unresponsive HRV; greater heart rate (HR) reactivity and prolonged HR-recovery after cognitive challenge. Fatigue levels, perceived effort and distress did not affect cognitive performance. HRV was consistently associated with performance indices and significantly predicted variance in cognitive outcomes.

These findings reveal for the first time an association between reduced cardiac vagal tone and cognitive impairment in CFS and confirm previous reports of diminished vagal activity.

I gathered from your reference to parathyroid surgery that you probably had something going on along those lines. However, please realize that doesn’t make you somehow magically CFS-immune. And it doesn’t make CFS any less legitimate.

Perhaps I misinterpreted your comments viewing those with CFS as people who can’t sleep and summing up with, “You believe this crap, Jane?”

It probably just hit me wrong.

“But... Doesn’t this study show strong evidence that it *is* all in the mind?”

Insufficient blood flow to the brain caused by failure of the brain, heard and autonomic nervous system to regulate blood pressure when the body and/or brain are subjected to a stressor. For those with severe CFS, going from a supine to sitting or standing posture is sufficient to cause loss of blood to the brain in a relatively short time. This has nothing to do with lack of sleep as a primary cause.

http://cfids.org/

Thanks for the ping, Nully.

Please don’t minimize the varied and severe effects of CFS/CFIDS on the individual and the people who are loved by the victim.

It is NOT cut and dried, and while it certainly could explain to some extent the sleeping (or not) of a PWC, it my no means explains anything else.

With around 40 symptoms, the best the researchers can come up with is “we don’t know what causes it so we can’t find a cure.” And there are still many, in all walks of life, who still maintain it is a psychosomatic illness.

One should hope that no one you know should suffer with this.

“Another thing, of course, the endocrine system is forgotten about.”

IIUC, whenever the article discusses the sympathetic nervous system, it involves the endocrine system (part of the feedback loop that is defective in CFS):

http://en.wikipedia.org/wiki/Sympathetic_nervous_system

“The sympathetic nervous system is responsible for up- and down-regulating many homeostatic mechanisms in living organisms. Fibers from the SNS innervate tissues in almost every organ system, providing at least some regulatory function to things as diverse as pupil diameter, gut motility, and urinary output. It is perhaps best known for mediating the neuronal and hormonal stress response commonly known as the fight-or-flight response. This response is also known as sympatho-adrenal response of the body, as the preganglionic sympathetic fibers that end in the adrenal medulla (but also all other sympathetic fibers) secrete acetylcholine, which activates the great secretion of adrenaline (epinephrine) and to a lesser extent noradrenaline (norepinephrine) from it. Therefore, this response that acts primarily on the cardiovascular system is mediated directly via impulses transmitted through the sympathetic nervous system and indirectly via catecholamines secreted from the adrenal medulla.”

“I notice that throughout most of my worknight: when I get up from a crouch, more often than not I feel lightheaded.”

When you go from sitting to standing there is a blood flow from your upper body into your legs and abdomen and away from your brain. Your autonomic nervous system detects this and hormones are near-instantly secreted in the brain that cause increase in heart rate and constriction of blood vessels to force blood out of the legs and abdomen and maintain blood pressure in the brain.

The vagus nerve handles the part of the process of increasing heart rate.

As we get older or are compromised by illness or disease, this feedback loop is not fully effective and blood loss to the brain results. In some persons the loss is very quick while in others it may take minutes or hours for the blood flow to the brain to fall and even produce feinting if the person doesn’t lie down. Lying down eliminates the symptoms.

Another name for the CFS-associated symptom in this article is orthostatic intolerance.

In my case I cannot tolerate standing still for more than a few minutes and I can only tolerate sitting for two hours at a time, even with my legs elevated. Then I must lie down for at least a half hour to restore my ability to sit for another two hours. This is how I go through me day. There is NO fully effective medical treatment for this, yet.

(Midodrine and fludrocortisone are not effective for me for those thinking of that)

Lack of sleep has nothing to do with the defect in this mechanism. I use CPAP both at night and during my four lie-down naps during the day that restore my ability to sit up.

If I try to push past about two hours of sitting up, I experience increasingly uncomfortable “pre-syncope” a pre-feinting syndrome that eventually becomes painful and results in me passing out if I don’t lie down. This has been experimentally proved on me and thousands of other CFS patients in HUTT testing (Heads Up Tilt Table). They strap you to a table (so you can’t bend your knees to pump blood to your head) Then they elevate you to 70 to 90 degrees an wait to see if you pass out in agony and measure how long it takes. My last test was 15 minutes. Although there are false positive for some folks, most healthy people can last a half-hour during HUTT testing without ever getting stressed or passing out.

Its about Heart Rate Variability (HRV) and mental performance of CFS patients. The heart of a CFS patient doesn’t respond either soon enough or strong enough to mental and physical stress to maintain adequate blood flow to the brain. So CFS sufferers report “brain fog” or reduced mental clarity, particularly mental speed compared to normal folks (controls in the study).

In my experience (as can be seen in my comments in this thread) the lack of blood flow to the brain in CFS is often partly due to “blood pooling” in the abdomen and legs when the person sits up (from lying down) or stands up from either sitting or lying.

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