However, a caveat: many such proteins have also been found to be elevated in patients with psychological conditions.
Always nice to see you Dr Yes.
I think we should be cautious when we start worrying about such connections with 'psychological' conditions. Perhaps when we do so and regard them as clearly distinct from our own illness - which we emphasise is physical, not psychological - we are applying the same 'insult' to those people that we resent so much ourselves. I do have this suspicion that as this all unravels and we find the mechanisms behind ME/CFS, there may well turn out to be biological revelations and connections made that relate to some 'mental' illnesses as well.
Of course we are accustomed to wanting to draw a sharp line between ME/CFS - a physical illness - and 'psychological' illnesses...but it's worth bearing in mind that in the field of 'mental illness' we really know almost nothing about what causes 'bipolar disorder', 'schizophrenia', etc etc. We don't even have them well enough categorised to clearly distinguish one from another and know what distinct types of 'mental illness' there really are. Viruses are now being found in relation to those conditions as well...so it could turn out that what we see as the unfair labelling of ME/CFS as a 'psychiatric' or 'psychological' condition is equally the case for these other 'mental illnesses': they too may have viral, retroviral, or similar pathophysiology; they too are ultimately physical illnesses and not 'psychological'.
So we could tie ourselves in knots if we start worrying that the results apply also to, say, bipolar disorder, or even depressive illness, and start saying that may mean the cohort wasn't properly characterised, or worrying that a particular study might be used to suggest that we have a 'mental' illness after all and getting all flustered about that. We know that ME is a neurological condition: it affects the brain and nervous system; the cognitive impairments we all experience are part of that. Why wouldn't the type of disease processes involved be similar to disease processes involved in 'mental illnesses' that are also likely to have a physical cause located in the brain?
Wouldn't it be great if the big breakthroughs for us turned out to be just part of a wider breakthrough in the understanding of 'mental illness' in general? The important thing is to continue to emphasise the physical basis of what's observed. I do suspect that's what's going on here: the beginnings of a better understanding of neurological disease in general...and those psychological approaches to these illnesses could be consigned to the dustbin right across the board, one day. So if we find the same sort of proteins in relation to a variety of 'mental illnesses' as well, then I would be excited for all the people locked away in asylums, rather than worried that this is going to mean people say we have a 'psychological' condition after all.
(They probably will continue to say that...but that will become increasingly irrelevant, is my guess).
Of course, none of that is to say that we shouldn't also be demanding well-characterised cohorts, whatever is being studied...mixing everything up together isn't a good approach to studying something, as we know all too well...