Simply being in pain gives your ability to think a hit. The cognitive and pain problems people with fibromyalgia experience appear to be associated with a sluggish autonomic nervous system.  Despite being ‘on’ most of the time the autonomic nervous system  in FM tends to poop out when faced with stress. That’s  unfortunate as reduced ANS functioning  during activity and increased ANS activity when resting are both associated with increased pain. The low blood pressure sometimes found in FM can increase pain levels further.

From sleeping, to concentrating on a task, to simply enjoying ourselves, pain has the ability to affect us in so many ways. The origin, though, of the kind of pain ME/CFS/FM patients experience, is still something of a mystery.

We’ve been looking at the role autonomic nervous system problems play in everything from sleep to fatigue in ME/CFS/FM over  the past month or so.  Now we take a look at two big symptoms – pain and thinking ability – in two fibromyalgia studies and try to figure out what’s causing them.

In the first study Spanish researchers had their FM patients do a math test, assessed their blood pressure, asked them to do a bunch of self report tests and threw everything together…

Eur J Pain. 2012 Mar;16(3):421-9. doi: 10.1002/j.1532-2149.2011.00032.x. Epub 2011 Dec 19. Cognitive impairment in fibromyalgia syndrome: the impact of cardiovascular regulation, pain, emotional disorders and medication. Reyes Del Paso GAPulgar ADuschek SGarrido S.

Slower at the Uptake

learning curve

People with fibromyalgia didn’t learn quite as fast as healthy controls on one test

People with fibromyalgia took longer to do math tests than the healthy controls.  Reduced ‘mental speed’ ‘ may not seem like a big deal  but  it turns out that rapid information processing is critical to carrying out more complex cognitive tasks. In fact, problems in this critical area are assumed , the authors noted, to be a ‘global indicator of neurobiological damage’.

The fact, on the other hand, that the  FM patients were no more error prone than the healthy controls suggested that their particular deficits were in working memory and executive functioning – exactly the same problems found in people with chronic fatigue syndrome (ME/CFS).

‘Learning Potential’ Smacked

Do you have more difficulty learning new tasks? Rather unsettlingly, the tests indicated people with fibromyalgia simply weren’t all that good at learning new tasks.  In the 2-minute arithmetic test most people -as they get acquainted with the test –  do better during the second minute of the test.  The people with FM got a bit better but the healthy controls got alot  better, suggesting. as the authors put  it, that the FM patients had ‘limited adaptivity to new situations’.

Mood  and Anxiety Flame Out (Again) – Pain Scores Big Time

Once again neither anxiety nor depression were associated with cognitive issues. With that horse apparently beaten to death the authors looked around for other causes and found a seemingly obvious one – pain.


Pain was a big contributor to the reduced performance seen on some cognitive tests for people with FM

The degree of pain the FM patients reported was strongly negatively  associated with performance on the cognitive test; the less pain a person was in the better they tended to do and vice-versa. Patients on opiates – presumably because of the pain reducing effects – tended to better on the tests than patients not on opiates.

The fact that  pain can and will reduce concentration and performance on any task has been demonstrated many times. Studies indicating that  pain increases activity in parts of the brain used to carry out tasks (prefrontal cortex, anterior cingulate) suggests what pain sufferers intuitively feel; that people in pain require enormous mental resources  simply to screen out pain enough for them to focus on a task.

High levels of pain  impair working memory and ‘executive functioning in people with fibromyalgia

In this context it’s interesting that a meditation manual I just saw instructed  meditators experiencing severe pain to gather all their mental resources and in effect, stiffen themselves themselves mentally  as they focused on that  overwhelming stimulus; there’s no playing around with severe  pain even for skilled meditators.

The Strange Blood Pressure Connection

Higher blood pressure is usually  associated with reduced cognitive performance but this was not true  for the people with fibromyalgia. It’s possible that the lower blood pressures found in the FM group meant blood pressure levels never got to the point where their cognitive abilities declined.  That would seem to be a plus but it may also point to a problem  in their cardiovascular system that not only causes them more pain but places them at increased risk of cardiovascular disease, as well…

That problem was simply a lack of response…..Not only did the FM patients have slightly lowered blood pressure but  their cardiovascular response to stress was, in a word, sluggish. Blood pressure should increase slightly as we take on tasks and the heart distributes blood to the areas involved  but the FM patients cardiovascular response was sluggish compared to healthy controls, and that, interestingly enough might have everything to do with the pain they feel.

Sluggish Is As Sluggish Does

J Psychosom Res. 2011 Feb;70(2):125-34. doi: 10.1016/j.jpsychores.2010.09.012. Epub 2010 Nov 18. Autonomic cardiovascular control and responses to experimental pain stimulation in fibromyalgia syndrome.Reyes del Paso GAGarrido SPulgar ÁDuschek S.

In the second study these Spanish researchers provoked a pain response and then measured FM patients cardiovascular response to it.

blood pressure

The reduced blood pressure response to stress found in FM is also associated with more pain.

To put it simply the FM patients cardiovascular was underwhelming at best; their stroke volume – the amount of blood pumped out by their hearts,  the amount their hearts contracted, their heart rate variability and their cardiac baroreflex response – which maintains blood pressure…were all significantly inhibited relative to the health controls…Their cardiovascular system basically wimped out.

They displayed a strange pattern  we’ve seen before;  although their sympathetic nervous system was always ‘on’, putting it under stress caused it to poop out. This suggested the ANS is the source of the ‘wired but tired’ problem; it can’t disengage and then flops when it’s asked to respond.

A Central Response System Blunted

A key system controlling FM patients blood pressure appears to be under particular stress in FM.  The baroreflex response keeps our blood pressure under control by controlling our heart rate; if our blood pressure rises too high,  it tells the brain to slow our heart rate down. The brain then tells the autonomic nervous system to do that. If our blood pressure drops too low it  does the opposite.

The cardiovascular systems of people with fibromyalgia responded poorly to ‘stress’

(It does this using receptors called mechanoreceptors (eg baroreceptors) that line our blood vessels. If our blood pressure rises too high the mechanoreceptors stretch and, in doing so, send a signal to the brain to slow our heart rate down.  If they’re not stretched at all (ie if you have ‘loopy’ blood vessels :))  they signal the sympathetic nervous system to become activated).

The FM patients baroreceptor response  (baroreflex sensitivity) was muted. A similar problem seems to be occurring in chronic fatigue syndrome (ME/CFS).   A recent study by the Newton Group indicated systolic blood pressure  was muted when ME/CFS patients stood up. Reaching further back Peckerman found reduced baroreflex sensitivity in  2001 and  2003 in both Gulf War Syndrome and ME/CFS patients.

This study indicates that CFS alters baroreceptor reflex functioning..(and was) accentuated in the patients with severe CFS….Arnold Peckerman (2003).

System Burnout

burnout in ME/CFS

Is the autonomic nervous system too burnt out to respond well to stress? Some studies suggest it is…

Wyller’s finding of reduced systolic blood pressure variability upon standing  in ME/CFS and increased sympathetic nervous system activation suggested to him that  the stress response system was approaching burnout and he proposed that it might  collapse (ie not respond)  under more severe stressors than standing.

(Such as exercise?…Is the ‘collapse’  in the  ability to produce energy some ME/CFS patients demonstrate when they undergo a second-day of exercise testing the result of sympathetic nervous system ‘collapse’ ?)

The Pain of it All

Of all the autonomic measures tested, one – the baroreflex sensitivity (the ability to modulate blood pressure in response to stress) was highly associated with pain in the FM patients. That is, FM patients with more pain were less able to alter their blood pressure in response to stress than were patients with less pain.

As an added bonus, the more ‘adjustments’ ones baroreceptor’s made over time; ie the more active their baroreceptors  were,  the more tolerant of pain  that individual was.  The more sluggish the autonomic nervous system was  the more likely that person was going to be in pain.

 A reduced ability to regulate blood pressure in fibromyalgia appears to be associated with increased pain 

What’s going on here? How could problems in the cardiovascular system be associated with more pain?  In fact the relationship between increased baroreflex sensitivity and reduced pain and between low blood pressure and increased pain is well known. If you have lower blood pressure or if your cardiovascular system just does not respond to stress well, it’s likely you’re going to be in more pain.

It gets worse.  Central sensitization and chronic pain are also associated with increased resting  blood pressure -which can be found in both ME/CFS and fibromyalgia.   If you have the weird combination of increased resting blood pressure/heart rate  but a sluggish blood pressure response to stress; ie if you have the wired but tired syndrome found in ME/CFS/FM you’re on track for more pain…

The significant role the autonomic nervous system plays in pain production in FM/ME/CFS suggests getting it under control could be very helpful.

The Cause?

Nobody knows what’s causing this but some attention has been drawn to the ‘rostroventral medulla’  in the deep brain which controls both hypersensitivity to touch and  temperature and the baroreflex response.  Some researchers believe  constant pain signals from the body  cause neurons to grow that somehow intermix both pain and cardiovascular signals.

Let’s end this on the happy note that lower baroreflex responsiveness is associated with increased risk of cardiovascular events (eg. heart attack and stroke). Several studies suggest people with ME/CFS have indices associated with increased cardiovascular risk.


Simply being in pain gives your ability to think a hit. The cognitive and pain problems people with fibromyalgia experience appear to be associated with a sluggish autonomic nervous system.

Despite being ‘on’ most of the time the autonomic nervous system  in FM tends to poop out when faced with stress. That’s  unfortunate as reduced ANS functioning  during activity and increased ANS activity when resting are both associated with increased pain. The low blood pressure sometimes found in FM can increase pain levels further.

Constant pain signals from the body that cause neurons to mistakenly intermix signals could be contributing to the pain, cognitive and autonomic nervous system problems in ME/CFS/FM.

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