Paywall, https://www.sciencedirect.com/science/article/abs/pii/S0022399919309055 Scihub, https://sci-hub.se/10.1016/j.jpsychores.2019.109845
The problem with measures of HRV is they are quite non-specific. A lack of fitness in general is a strong predictor of lower HRV. Sleep disruption and other factors can also alter HRV as discussed in the editorial. The findings (across more than a handful of studies I have seen) tend to show lower HF, rather than a reduction in LF influence, which suggests lower parasympathetic activity, rather than increased sympathetic activity which lends further weight to the hypothesis that the HRV findings are primarily due to lower fitness/activity levels. I agree. There have been a small number of studies already that have not found anything specific, likely due to significant within-group variation. Friedburg cites the 'sustained arousal' model, but fails to note that the findings of higher catecholamines has only been found in adolescents by one research group and may reflect the social context of the testing (of ill adolescents), rather than be a generalised finding. Notably, this finding has not been replicated in adults.
Not sure how the editorial is related to the two studies announced here: https://reporter.nih.gov/search/MFkYFqJYG0-YuVKog5mE5Q/projects Some details could be relevant for discussions on research methodology and hint to caveats that apply for ME research in particular. Not able to explain now or link to relevant discussions on other threads, so just leave the links to the study reports here: https://clinicaltrials.gov/ct2/show/NCT02948556?id=NCT02948556&draw=2&rank=1&load=cart https://clinicaltrials.gov/ct2/show/NCT03331419?id=NCT03331419&draw=2&rank=1&load=cart
There may well be something wrong with these systems in ME but this is awfully close to ideas like central sensitisation and other BPS ideas. If the sympathetic nervous system is hyperactive then you are anxious so CBT and mindfulness will cure you. If they are going wrong in ME it is more likely that it is the result of the body being so physically damaged that we are like someone who is in cardiac failure not a healthy body reacting abnormally to the outside world. Researchers need to be aware of the way their research could get abused and make sure they protect us.
Research project with $400,000 of funding in 2016. Led by Fred Friedberg, expected completion date May 2020. No results posted to date. Brief Summary:
Am I misreading this? That sounds like they are prejudging activity levels as good and bad. Specifically, the low actvity counts are predicted to be associated with high symptoms severity. Surely that's inevitable, since sicker patients are by definition less able to be active. It's the last one that bothers me particularly, following on from the severe one: 'a healthier pacing pattern... So they seem to be judging those with moderate activity able to pace and still have some activity levels as showing 'healthier' behaviour than the very sick able to do less. I think hypotheses like this, although they are careful to use association not causation as their word relating activity to symptoms, need to be more careful not to add any value laden hints to their wording and order of examples and order of sentences. Here's what I would prefer as the wording, that includes no value judgements or implied directions of causation: Specific Aim 3: To assess the relation between symptoms and activity patterns. Hypothesis 3: (a) there will be a direct association between activity variability and symptom variability; (b) there will be an inverse association between overall symptom severity level and mean actigraphy count.
This is the inclusion criteria for that study: It's a bit sad when the President of the International Association of CFS/ME is not requiring participants in his ME/CFS research to have PEM.
Too many of these researchers think of CFS even if they now say ME. They have no idea of what our disease does to us. Thinking about it, people with unexplained fatigue must outnumber those who specifically have ME especially as people with ME give up on the medical profession, so the ones they see the most are similar to each other and do not have PEM but more of a post exertional fatigue. PEM is so nonspecific that the 6 months of fatigue could then seem to cover it as the cardinal symptom. I can't see why they do it otherwise.
