PEM - What do physical and mental exertion have in common?

[CFS_for_19_years]

At 8 minutes in, there's a slide showing that emotional stress activates the immune system and HPA axis. Then later, she shows how pacing reduces gene expression, so conversely, one could assume that the stress of mental exertion affects gene expression and causes PEM.

 

[Kati]

Here is my reasonning. Physical and mental exertion requires more oxygenation and blood flow to the tissus. For physical exertion, the muscles need increased blood flow. For mental tasks, the brain requires increased blood flow. We seem to lack that 'switch' to accomodate these needs.

 

[beaker]

Here is my reasonning. Physical and mental exertion requires more oxygenation and blood flow to the tissus. For physical exertion, the muscles need increased blood flow. For mental tasks, the brain requires increased blood flow. We seem to lack that 'switch' to accomodate these needs.

We also have low blood flow to the brain and low blood volume in general to begin with.

 

[Marco]

My banged together theory is that we could use our brains all day in 'default network mode' http://en.wikipedia.org/wiki/Default_mode_network, daydreaming or 'mind wandering' mode.

It's 'mind focused' mode or task positive mode that causes problems for me. http://en.wikipedia.org/wiki/Task-positive_network . There seem to be more energy drain when I am trying to focus or achieve a task.
And I can't dissociate task driven focus from some form of stress in our brain, however little, which I think kicks off part of our HPA axis which feeds into our whole me/cfs conundrum of dodgy cortisol and cytokine release, (subsequent microglial activation in the brain).

Complex tasks which I learnt pre-me/cfs/lyme are easy enough to do by old habit. But If I had to learn something complex and new I am absolutely screwed.

I would tend to suggest the opposite. I agree that task focussed activities cause more problems - I'm pretty OK when 'pottering' but I'd also add that my symptoms are less noticeable (or noticed) when I'm engaged in something which is pretty much true for everyone healthy or not.

But I think the siutation with ME/CFS may be analagous to findings in fibromyalgia and other chronic pain conditions. Even when in default network mode (which they suggest should be 'down-time' - reflective and calming) they are reflecting (or ruminating to use a perjorative term) on their symptoms via the amygdala.

Perhaps even the time we spend in this supposed restful and recuperative mode continues to be stressful which makes task oriented states more demanding?

http://www.medpagetoday.com/clinical-context/Fibromyalgia/33547

.

 

[Marco]

Here is my reasonning. Physical and mental exertion requires more oxygenation and blood flow to the tissus. For physical exertion, the muscles need increased blood flow. For mental tasks, the brain requires increased blood flow. We seem to lack that 'switch' to accomodate these needs.

Sounds plausible. To add to this the autonomic pattern apparently found in ME/CFS (reduced parasympathetic/increased sympathetic, reduced heart rate variability) may mean that we fail to produce the required sympathetc response to 'effort' that should result in increased blood flow to the affected muscles or brain (the crying wolf principle?).

 

[beaverfury]

But I think the siutation with ME/CFS may be analagous to findings in fibromyalgia and other chronic pain conditions. Even when in default network mode (which they suggest should be 'down-time' - reflective and calming) they are reflecting (or ruminating to use a perjorative term) on their symptoms via the amygdala.

Perhaps even the time we spend in this supposed restful and recuperative mode continues to be stressful which makes task oriented states more demanding?

http://www.medpagetoday.com/clinical-context/Fibromyalgia/33547

Hm. I don't really know. I wish my brain worked better so I could get further into this.

This article shows the connection between ruminating in default mode and pain in fibromyalgia. I can believe the connection.

But if we are talking about PENE, getting exhausted after mental exertion in me/cfs, I wonder if the error detection that is part of focused task positive thinking subtly sets off the flight/flight response and exhausts us.

The anterior cingulate cortex and amygdala seem to have close communication.

'A typical task that activates the ACC involves eliciting some form of conflict within the participant that can potentially result in an error.'
'... the ACC is connected with amygdala, nucleus accumbens, hypothalamus, and anteriorinsula, and is involved in assessing the salience of emotion and motivational information. The ACC seems to be especially involved when effort is needed to carry out a task such as in early learning and problem-solving.[6] wiki

The ACC exhibits activity when it perceives a context where error could occur. These same contexts can also set of hypoperfusion and orthostatic intolerance in me. I had an embarrassing incident in the bank yesterday where I had to slump in their sofa for five minutes to gather myself. I was stepping up to the counter to sort out a very small issue.
The old me wouldn't have seen the contexts as stressful, but below the level of conciousness the brain is still detecting and judging. In a me/cfs compromised brain the smallest trigger may set off the HPA axis.

The biopsychosocial school may have made one keen observation involving me/cfs and effort perception, at least as concerns my illness. When I perceive, consciously or unconsciously, that a situation is going to be too much for me I already set off that stress response. My brain knows I don't have the energy backup to do tasks so maybe it shuts me down for a good reason.

 

[beaverfury]

I would like to know how @alex3619 , @Hip , @Snow Leopard brains operate in these regards .

 

[Marco]

Hm. I don't really know. I wish my brain worked better so I could get further into this.

Seems to be working fine to me. I'll have think a little about your post and get back to you.

The biopsychosocial school may have made one keen observation involving me/cfs and effort perception, at least as concerns my illness. When I perceive, consciously or unconsciously, that a situation is going to be too much for me I already set off that stress response. My brain knows I don't have the energy backup to do tasks so maybe it shuts me down for a good reason.

One of the older names for the various syndromes like neuraesthenia/soldier's heart etc was effort syndrome which at first might seem demeaning or patronising but it does (for me) neatly encapsulate the subjective experience.

 

[taniaaust1]

I think emotional stress gives me worse PEM than mental effort. Thinking effort is more just either possible or not possible.

This could be because emotion involves more whole-body stuff? Adrenals, heart, skeletal muscle, gut, etc.?

Emotional stress impacts me less then physical stressors and thinking/mental effort stressors.

I do think its very interesting thou that both mental and physical stress can do similar things to me eg too much and I get a sore throat, feel feverish or actually go feverish etc.

 

[taniaaust1]

I would like to know how @alex3619 , @Hip , @Snow Leopard brains operate in these regards .

? Why them, are their brains ME superior specimins.. lol Im only kidding.

If its any interest to you, my brain issues are like you described.

 

[adreno]

@beaverfury

The anterior insula (AI) and ACC are the main components of what is known as the salience network (SN). The SN is involved with the detection of salient stimuli (both external and internal) as well as the engaging/disengaging of appropriate neurocognitive network resources. It acts as a switch between the task positive network (also known as the central executive network, or CEN) and the default mode network (DMN). When the SN is dysfunctional, the DMN is not correctly disengaged during tasks, and at the same time the CEN is not correctly engaged (and vice versa).

 

[beaverfury]

? Why them, are their brains ME superior specimins.. lol Im only kidding

If its any interest to you, my brain issues are like you described.

Nah! I just plucked them out at random

Actually , Hip has already dealt with this, here - http://forums.phoenixrising.me/inde...-get-togethers-with-family-and-friends.32814/

 

[Valentijn]

I've been trying to identify postural patterns. It's odd that your calves hurt when sitting. Mine get weaker when I sit a lot.

It's very very common for ME patients to get weaker as a result of doing more. We don't really seem capable of building up muscle stamina properly, and our muscles wear out very quickly.

When I've been forced to bed rest due to very low blood pressure, after it passes some weeks later I'm actually significantly stronger than I was prior to starting the bed rest. My muscles have then rested up and have some energy reserves which seem to keep them functioning for longer.

More bed rest might be quite useful generally, but it's far too boring and painful to do it unless I don't have any choice.

 

[alex3619]

I suspect, and its only hypothetical, that mental exertion in us is very multidimensional. Some mental efforts can wipe me out in five seconds, but on a good day I can do others for many hours. Different parts of my brain respond differently. Serious math ... seconds. Light reading ... some time. Heavy reading ... minutes. Watching boring dvds ... not long but its the boredom that gets me. Watching good dvds ... hours on a good day, twenty minutes on a poor day, and zero on a bad day. I do not write many blogs these days as the mental gymnastics are currently beyond me most of the time. However I can write posts like this.

One thing I do want to comment on. I play a lot of computer games, and have been playing them since the 80s. These days there is a lot of online gaming, some of it can be done with other people. The pace they choose to play at wipes me out in minutes. However I find I can play with another ME patient for hours online, as we both pace ourselves to our capacities. Indeed I did some online gaming with an ME friend of mine earlier today, though we did both get a bit wiped out at the end.

Physical exertion is more straightforward .. you have the energy, coordination and strength or you don't. Mental demands are much more varied and subtle.

 

[Snow Leopard]

@Snow Leopard brains operate in these regards .

I believe I have much greater mental endurance than most people (it might be genetic, my father is an ultramarathon runner). I had a very long attention span before I first became ill. I can push quite hard mentally (learning how to concentrate with ME is very difficult...) or physically. Naturally there are consequences. I can push up to a point, dealing with the extra pain, but pushing too hard and my ability drops off a cliff walking becomes difficult, or I literally cannot solve anything requiring intelligence (is a real problem after two hours of a science exam), or I feel dizzy, about to pass out and.

But while mental expenditure sets me back days in terms of mental fatigue, it does not seem to increase the fatiguability of the rest of my body (example: after a uni exam). On the other hand, exercise does increase my mental fatigue. Since I experience a headache 24/7, for over a decade, I kind of use the severity of my headache and (in)ability to concentrate as a gauge for my level of mental fatigue.

Other experiences, like trying to read a book in 4 days (Pratchett's "long war") has led to more than 4 days of extremely sore eyes and increased mental fatigue.

As far as effects of emotional exertion, anxiety, go, the experience may to some feel like fatigue, for there is a sort of 'dull' or 'numb' feeling, reduced concentration and increased drowsiness. Maybe this is a dysthymic feeling, I don't know, but it feels quite different to the day to day fatigue.

 

[Valentijn]

But while mental expenditure sets me back days in terms of mental fatigue, it does not seem to increase the fatiguability of the rest of my body (example: after a uni exam). On the other hand, exercise does increase my mental fatigue.

Same for me. Physically-induced PEM affects body and mind. But a cognitively-induced crash doesn't affect my body, just my ability to think straight, plus likely headache.

 

[Marco]

I'd still like to identify one or more 'signals' that could be common to physical and mental exertion.

In the meantime I'm going to suggest a possible mechanism for PEM and for the purposes of this I'll assume both mental and physical exertion produce signals through pathways such as those proposed by the Lights.

Second assumption is that we have a state of miscroglial priming which we have at least preliminary evidence of.

Third assumption is that microglial activation has compromised/dysregulated frontal cortex function (grey matter volume and white matter connectivity findings plus impaired executive function might support this assumption). The frontal lobe plays an inhibitory role on the autonomic nervous system and impaired function (as I understand it) can result in reduced vagal tone (parasympathetic) and reduced heart rate variability.

During physical or mental exertion signals of pain and/or fatigue are processed through the nervous system where they are determined to be salient (sustained not by false illness beliefs but experience) and avtivate primed microglia releasing a cascade of pro-inflammatory cytokines (not good).

The normal response to this stress would be to activate sympathetic nervous system vasodilation to improve blood flow to skeletal muscle and the brain. But impaired frontal cortex function has maintained the ANS in an ongoing 'sympathetic dominant' state with the effect that vasodilation doesn't happen (due to habituation). Increased blood flow doesn't happen, you may get ischemia and metabolites are not cleared as they should be with obvious effects.

So we have signals that effort is causing stress but the expected reponse of increased blood flow isn't happening. From an abstract perspective what would we then expect to happen in a system capable of feedback? I would suggest that if a signal doesn't appear to have been received you would either re-send the signal and/or boost the level of the signal. Could this be what the Lights found when exercise triggered a massive increase in gene expression of receptors in pathways dealing with pain and fatigue?

This has all the makings of a positive feedback loop. The failure to respond appropriately to initial stress signals by increasing blood flow results in a ramping up of the signals all of which are hitting primed and activated microglia. Only complete cessation of activity would stop this loop spiralling ever upwards and who knows – it might even contnues on this trajectory for a while afterwards perhaps explaining delayed PEM (not to mention that microglial activation could persist over a longer timescale).

Too simplistic?

 

[MeSci]

I'd still like to identify one or more 'signals' that could be common to physical and mental exertion.

In the meantime I'm going to suggest a possible mechanism for PEM and for the purposes of this I'll assume both mental and physical exertion produce signals through pathways such as those proposed by the Lights.

Second assumption is that we have a state of miscroglial priming which we have at least preliminary evidence of.

Third assumption is that microglial activation has compromised/dysregulated frontal cortex function (grey matter volume and white matter connectivity findings plus impaired executive function might support this assumption). The frontal lobe plays an inhibitory role on the autonomic nervous system and impaired function (as I understand it) can result in reduced vagal tone (parasympathetic) and reduced heart rate variability.

Do we have reduced heart rate variability? Mine seems to vary quite normally with exertion.

 

[Marco]

Do we have reduced heart rate variability? Mine seems to vary quite normally with exertion.

As far as I know its a repeated finding but relates more to the natural variation in inter-beat intervals of resting heart rate. Think of it like a modern jet fighter that is so unstable that it can only be flown with the help of computers - but this gives it enhanced agility and responsiveness. The heart needs to be the same. Reduced heart rate variability means reduced ability to respond appropriately to demands.

 

[Marco]

@MeSci

I'd have to dig out the refs but I did have this to hand :

"Electrocardiograph (ECG) measurement of heart RR (beat to beat) intervals (Wikipedia – Heart Rate Variability) is intended to measure the ratio between the sympathetic and parasympathetic sides of the nervous system, with the low frequency component (LFC) reflecting the sympathetic and the high frequency component (HFC) the parasympathetic system."

"As with other findings CCFS patients, as a group, showed evidence of autonomic dysfunction. (Freeman and Komaroff, 1997; Newton et al., 2007; Beaumont et al., 2012). CCFS patients had low parasympathetic function, or in other words, sympathetic dominance which reflected a sustained response from the ‘fight and flight’ side of the autonomic nervous system."

Read more: Japanese Sensory Gating Study Reveals Profound Cognitive Deficits Present in Chronic Fatigue Syndrome http://www.cortjohnson.org/blog/201...deficits-present-in-chronic-fatigue-syndrome/

OK - I'm quoting myself