Discovery and Identification of fatigue-Related Biomarkers in Human Saliva, Xu, 2008.

https://www.europeanreview.org/wp/wp-content/uploads/8519-8536.pdf

See table 1 for protein vs HCs. Brought up as I read a post by @Andy about a possible study on salivary peptide fatigue testing in me/cfs. Could this be useful to find a biomarker in me/cfs?

 

I had not read the full study and struggle with following the biochemical terminology (something I would have had no problem with pre ME), but this seems an interesting early step in developing objective markers related to fatigue. However, it is important to recognise that fatigue is likely to prove to be much more complicated than the ‘normal’ short lived fatigue experienced by a relatively homogenous subject group in relatively narrow circumstances.

As the article indicates fatigue is a potentially very complex phenomenon; we have no idea how ‘normal’ readily reversible fatigue relates to chronic fatigue experienced in so many different pathologies or if fatigue associated with these different pathologies even approaches being a unitary phenomenon. Also, as illustrated by discussion here, it is very difficult to tie down the variety and variation in fatigue as a subjective experience.

For me this technique is less of interest as a biological indicator of normal fatigue, but as a potential tool to indicate the variation in physiological states associated with the subjective experiences of fatigue, variation between different pathologies and variation over time within individual conditions such as ME.

 

There is also the fact that ME is a disease of energy production. The Workwell research has shown that at least a subset of patients with ME have a broken aerobic system so they are forced to rely on emergency energy production for the tasks of daily living to a greater or lesser extent.

Many diseases like MS and RA have a lot of fatigue due to needing extra energy to move damaged limbs - like the difference between carrying a handbag or two packed shopping bags up a hill. They produce energy normally but need more of it.

So while ME patients may well experience that common type of fatigue a lot of what looks like fatigue is actually a different type of damage where there is not enough energy available in the first place.

 

The sensitivity/specify for each of the proteins was fairly weak so I can't conclude much from this study. Yes, we can pool the results together, but until the algorithm is tested on another cohort, we don't actually know how accurate it is.

 

To me it is like the ME/CFS patient being akin to a car having a problem with its engine, or fuel supply etc, so the flow of energy cannot meet what are perfectly normal energy demands.

Whereas the other case is akin to the engine, fuel supply etc being perfectly OK, but the brakes are sticking on, so the engine is having to work much harder to try and meet the much higher than normal energy demands being made upon it.

 

I think of it like a laptop's lithium-ion battery that has degraded. It can charge, but capacity is much reduced and needs to be plugged in frequently (premature reduction in cycle-life). See most any teenager's iPhone / Android.