18 young, previously healthy people. Mild COVID, nobody hospitalized. Six months later, they're still dealing with brain fog, worse sleep, anxiety, low mood. On a test of inhibitory control they did just as well as controls.
But their EEG told a different story about how their brains got there🧵
Neurocognitive Indices of Long COVID: Dysregulated Engagement of Inhibitory Control and Oscillatory Slowing
🚨Even after mild COVID, LongC0VID can leave a measurable brain signature.
Interesting small USA study that needs your attention:
➡️~6 months later, young, otherwise healthy adults with PASC reported more brain fog, anxiety, depression and sleep problems,
➡️On an inhibitory Go/NoGo task their performance looked intact, but EEG did not,
➡️Neural indices showed altered cognitive-control engagement on both correct and error trials, less efficient responding, and a trend toward dysregulated co-oscillatory synchrony during errors,
➡️Altered neural indices of inhibitory control marginally correlated with spontaneous oscillatory slowing, potentially suggesting shared basic mechanisms,
➡️“The overall pattern of PASC symptoms, altered neural activity during inhibitory control, and oscillatory slowing, is indicative of the core neural dysfunction characterizing PASC”.
‼️So, LongC0VID here is not symptoms without a signal. It is a core neural dysfunction that behavioral tests miss and EEG detects.
‼️In layman terms: After even a mild COVID infection, some people keep the fog, the bad sleep, and the low mood. Everyday tests may say nothing is wrong. The brain however can be working less efficiently, especially when it has to stop itself, stay on task, or recover from a mistake, and to be honest, I'm seeing a lot of this around me!
#AvoidSars2 #AvoidReinfections
mdpi.com/2673-4087/7/5/105
mdpi.com/2673-4087/7/5/105/p…
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18 people with long COVID (average age 25) vs 20 controls who never had COVID. The main task was Go/NoGo - press a button when the letters alternate, hold back when one repeats. Plus five minutes of resting EEG.
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In many ways this is the mildest cohort you could pick. Participants rated the overall impact on their lives as moderate, but functional limitation in daily activities came out at 0.8 out of 4, essentially none. These are the people who typically get told there's nothing wrong with them.
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On the task itself, no difference between groups, in accuracy or in reaction time. By any behavioral measure, they look fine. A standard workup would stop right here.
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First. When you engage cognitive control, theta activity (4-7 Hz) rises over the frontal and central scalp. It's a well-established index of how hard the brain is recruiting control. In long COVID it was lower on correct inhibitions, on correct responses, and most strongly at the moment of an error. After multiple correction.
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In the LC group, lower theta went hand in hand with slower responses (r −0.5). In controls, that link was essentially zero. Within the LC group, reduced engagement of control shows up in how fast people respond.
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The second finding is from resting EEG. Alpha peak frequency, the frequency where the alpha rhythm is strongest, was lower in long COVID, and more power sat in slow alpha (8-10 Hz) than in fast alpha.
Brain activity at rest had shifted toward slower frequencies.
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The picture fits a wider body of work. Other TMS studies found reduced cortical inhibition in long COVID, and other EEG cohorts have reported the same shift toward slower frequencies. The same lab previously measured lower GABA, the brain's main inhibitory neurotransmitter, that's their own research program.
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Small sample, one site. Controls were recorded just before the pandemic, the long COVID group from 2022 on. No group that had COVID without developing LC, so the effect of infection can't be separated from the effect of long COVID. A group level signal, not a test for individuals.
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HIV has a similar category. The mildest tier of HIV-associated neurocognitive disorder (ANI) means abnormal test results with no impact on daily life, and for a long time it was treated as marginal. Then longitudinal data showed a higher risk of progressing to the symptomatic form.
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Here we're one floor lower still - the test shows nothing, the neurophysiology does. That's a parallel in category, not mechanism.
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White at al., Neurocognitive Indices of Long COVID: Dysregulated Engagement of Inhibitory Control and Oscillatory Slowing. mdpi.com/2673-4087/7/5/105
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What this means at work/school is something the study doesn't measure. If the brain has less control in reserve - performance drifts over the day, more small slips, a slower return to pace after an error or interruption.
In healthy people, weaker brain responses to errors predicted more everyday self-control failures, Krönke 2018 - the authors cite it in the discussion.
@szupraha @ZdravkoOnline @VZPtweetuje
Sep 27, 2026 · 5:13 PM UTC
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