Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe ME/CFS patients, 2020, Van Campen, Rowe, Visser

Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

https://www.mdpi.com/2227-9032/8/4/394

 

That 10 of 90 patients self-reported no significant orthostatic intolerance despite being classified as severe ME/CFS and also had no significant reduction in cerebral blood flow during the test, could be an elegant demonstration that deconditioning is insufficient to explain the reduction in cerebral blood flow or severe ME/CFS.

It also suggests that orthostatic intolerance is not required to have ME/CFS (or that there is one subtype of ME/CFS that doesn't come with OI).

 

So blood pressure and heart rate did not change between being supine and sitting in either group, but the initial blood pressure was higher in the ME/CFS group (though not significantly so).

Is the implication that low blood volume in ME/CFS patients is behind the decreased cerebral blood flow? That is, when lying down, low blood volume still produces sufficient cerebral blood flow, but it is insufficient when sitting up? Shouldn't blood pressure and heart rate try to compensate for low cerebral blood flow? Maybe that only kicks in when things become more severe. i.e. when one is standing with low blood volume.

ETA:
If you have low blood volume but also have normal blood pressure could that be the result of constriction of your blood vessels. In other words might the constriction of your blood vessel be sufficient to maintain normal (or here, slightly higher) blood pressure while sitting, but, once you stand up, the blood vessels can't constrict anymore and you get low blood pressure and even lower cerebral blood flow?

 

People that exercise less would have less elasticity in their vessels and thus less perfusion. So you'd have vascular narrowing and low blood volume - not a good combination. For further reading:

Alosco ML, Spitznagel MB, Cohen R, et al. Decreased physical activity predicts cognitive dysfunction and reduced cerebral blood flow in heart failure. J Neurol Sci. 2014;339(1-2):169-175. doi:10.1016/j.jns.2014.02.008

And now the editorial:

In order to correctly perform this study, you would exclude healthy controls and replace them with sedentary controls and, of course, blind the doppler technician to the disease status of the patients, and you would probably want a dropout rate of about 20% instead of like 97,5% of them.

All patients using opiates (opioids induce cerebral vasoconstriction and decrease cerebral blood flow) should be excluded from the cohort. Benzodiazepines and other GABA-modifiers reduce cerebral blood flow, too. Instead, more than 75% of the patients included were on these items.