Cognitive Impairments in Two Samples of Individuals with ME/CFS and Long COVID: A Comparative Analysis, 2025, Sirotiak et al.

Cognitive symptoms are one of the required symptoms in many ME/CFS case definitions, so this seems like a circular argument.

 

This is still interesting, as it seems like the combo of ME/CFS + LC gives more cognitive symptoms.

 

I'm wouldn't be automatically sure of that, I don't think it follows directly. Here's my thinking:

I haven't read the study but whether it is interesting or even "true" depends fully on the definition of what ME/CFS with comobird LC is supposed to mean in this study context.

There's 4 scenarios here: You either have ME/CFS with no relation to Covid, you have had ME/CFS and develop Long-Covid on top of that (what that is supposed to mean is rather wishy washy and depends on the context), you have ME/CFS from Covid or you have Long-Covid without having ME/CFS.

The problem is for someone that already has ME/CFS to develop Long-Covid on top of that, means they will have to develop a new symptom or one of their existing symptoms have to worsen, which is the definition of Long-Covid. Since cognitive symptoms fits that bill you'd naturally expect this number to be higher (the same would apply to anosmia etc) without it necessarily being interesting but rather possibly being an artefact of the Long-Covid construct (a bit similar to how more Covid infections automatically means higher chances of Long-Covid purely by chance since you're expanding your timeframe of possibilities rather than anything else). On the other hand if someones cognitive symptoms with ME/CFS don't worsen, there's a lower chance they will be counted in the LC group. None of this would necessarily have much to do with Covid or Long-Covid (think for example that 50% of ME/CFS patients cognitive symptoms might worsen over a given timeframe, whilst for others it wouldn't, but you're setup would somewhat arbitrarily label them to distinct groups).

I'm by no means denying that things might not be as said or that Long-Covid doesn't cause cognitive problems or that cognitive problems might not worsen in ME/CFS following a Covid infection, but to know whether the results are interesting all depends on how rigorously these groups were looked at as part of the study.

 

@EndME good points.

I kind of jumped to a conclusion because brainfog is very common post-covid.

 

Clearly, being a doctor makes people have gone through medical school. Can't explain that.