Have your competent? doctors and hospital get research going on biomarkers of post stroke fatigue, so we can get protocols created that remove that fatigue! My idiot of a doctor just said I needed more cardiovascular fitness, i.e. more exercise. He never tested my fitness level which was at the kevel of an athlete.
3 years post stroke at a physical I had a resting heart rate of 54 at age 53, level of an athlete. My doctor asked what exercises I was doing; 'I've done no exercises for the past 3 years'. And now 20 years past the stroke my fitness has declined a bit, ALL BECAUSE MY STROKE MEDICAL 'PROFESSIONALS' COMPLETELY FAILED AT GETTING ME 100% RECOVERED! Still managed to get to Tiger's Nest in Bhutan at 10,240 feet in 2023
Researchers identify biomarker of cognitive fatigue in multiple sclerosis and long Covid
For many people with post-Covid-19 syndrome, also known as 'long Covid', the mental exhaustion, difficulties with concentrating, and impaired cognitive performance that characterise cognitive fatigue can be some of the most disabling symptoms. Cognitive fatigue is also commonly reported by people suffering from other post-viral conditions, as well as conditions such as multiple sclerosis (MS).
However, the underlying causes of this kind of fatigue remain elusive, write Stefanie Linnhoff at Otto-von-Guericke University, Germany, and colleagues in a recent paper in Psychological Medicine. That's largely down to its "subjective and often invisible nature", along with a lack of objective diagnostic markers, they write. In their paper, though, they describe what they believe to be a marker — one that they think could be used to monitor cognitive fatigue in people with a range of different disorders.
Linnhoff and her colleagues recruited 119 participants for their study. Of these, 36 were healthy controls, 33 had 'long Covid-related fatigue', and 50 had MS. All completed a questionnaire that asked about cognitive fatigue, and this led the team to identify 23 of the MS group as being fatigued, and the rest as non-fatigued. The team then used EEG to monitor activity in the participants' brains while they spent three minutes at rest with their eyes closed.
When the researchers analysed the EEG data, they were on the look-out for something called 'aperiodic activity' — irregular electrical signals that were once dismissed as a kind of background noise in the brain, but are now recognised as representing the overall balance between excitation and inhibition in neural networks.
Two neurotransmitters are crucial for this balance; the neurotransmitter glutamate increases excitation (meaning signals are more likely to pass between neurons), while GABA does the opposite. Having the right 'excitation/inhibition (E/I) balance' is important for healthy brain function, and, as the team notes, disruptions to this balance have been linked to various neurological and psychiatric disorders, including MS.
When the team compared the subjective fatigue scores from the participants with the EEG recordings, they found that higher fatigue was associated with lower, flatter, aperiodic values, reflecting a shift towards excitatory activity, in the frontal region of the brain. The long Covid and the fatigued — but not the non-fatigued — MS participants had similar aperiodic activity.
This type of activity in one area of the frontal region, in particular, seemed to be especially tied to fatigue scores. This was the left dorsolateral prefrontal cortex, an area that is important for a number of cognitive functions, including sustained attention and cognitive control. The team writes: "This… points to the dlPFC as a potential common hub of vulnerability in fatigue, possibly reflecting a final common pathway of disrupted cognitive control due to impaired E/I balance."
Further work would be needed to explore whether changes to the E/I balance cause cognitive fatigue, or whether the opposite is true and fatigue drives changes in this balance — as well as to explore whether, as the team suspects, these findings will be replicated in people with cognitive fatigue associated with other conditions. Teams elsewhere are also investigating other potential brain markers of cognitive fatigue; in a recent study of groups of people with myalgic encephalomyelitis and long Covid, for example, Maira Inderyas at Griffith University in Australia and her colleagues reported finding reduced connectivity between various brain regions, which they linked to blunted motivation as well as cognition.
Linnhoff and her colleagues now hope that their findings will pave the way for new, objective ways of assessing cognitive fatigue in patients, as well as for evaluating the effectiveness of treatments.
Read the paper in full:
Linnhoff, S., Kadosh, R. C., & Tino Zaehle. (2026). EEG-based frontal excitation/inhibition balance as an objective biomarker for cognitive fatigue across multiple sclerosis and Long COVID. Psychological Medicine, 56, e21–e21. https://doi.org/10.1017/s0033291725103024
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