- Long COVID affects nearly 40% of those with SARS-CoV-2 infection.
- Symptoms of long COVID include visual disturbances and cognitive impairment.
- Reduced oxygen supply to the cells of the nervous system can “silence” the cells. These “silent neurons” may be responsible for some long COVID symptoms.
- Increasing their oxygen supply using neuromodulation techniques can reactivate silenced cells of the nervous system.
“Long COVID” refers to lingering symptoms after infection with the SARS-CoV-2 virus that causes COVID-19. Generally, people with mild-to-moderate cases of COVID-19 get better within 1–2 weeks, but severe cases can go on for months.
Researchers do not yet fully understand long COVID — also known as long-haul COVID, post-acute COVID, or chronic COVID. Experts worldwide are trying to understand who is most at risk of its short- and long-term health effects.
Some studies have found that nearly 37% of people had long COVID symptoms up to 6 months after the infection, and half of those who did not require admission to the hospital had one or more symptoms of long COVID.
Long COVID Symptoms
The severity of the initial COVID-19 illness has little impact on the risk of having long COVID — even people with mild cases of illness can have symptoms of long COVID.
The most commonly described symptoms include:
- breathlessness and breathing difficulties
- fatigue
- cognitive impairment and brain fog, or difficulty thinking and concentrating
- anxiety and depression
- visual symptoms
Now, a recent study published in Restorative Neurology and Neuroscience has found that increasing blood flow using microcurrents may be an effective way to treat symptoms of cognitive impairment, vision loss, and fatigue in people with long COVID.
The study authors suggest that changes in blood vessel health, specifically small microvessels, reduced blood flow, and lack of oxygen are the main cause of central nervous system symptoms in people with COVID-19. They outline that hypoxia, or lack of oxygen, reduces metabolic activity and silences the neurons, or the cells of the nervous system.
The study
Researchers at the SAVIR-Center in Magdeburg, Germany, treated two females with long COVID symptoms using noninvasive brain stimulation (NIBS) to understand if neuromodulation could enhance blood flow and reverse visual impairment.
Researchers delivered alternating current stimulation of the eyes and brain and completed cognitive assessments before and after treatment.
Participants received 10–13 therapy sessions lasting 30–45 minutes each. The researchers briefly delivered electric currents through electrodes attached to the forehead while participants were sitting. After treatment, the participants rested for 15 minutes.
The study found that noninvasive neuromodulation using NIBS improved visual field loss in under 4 days.
The researchers noted improved blood vessel regulation in peripheral arteries and veins, with “all veins” showing an improved maximum vessel dilation of 113% and peripheral veins showing an average 300% change in vessel dilation after NIBS treatment.
As well as vision problems, the participants had reported serious cognitive defects. Both of these improved after treatment, with one participant also showing a positive 40–60% recovery in the cognitive tests.
How does it work?
The research team believed that vessels affected by COVID-19 in the brain fail to dilate due to swelling in the vessel wall. This reduces the blood flow and deprives the neurons of oxygen. Reduced oxygen slows cell metabolism and stops them from functioning. The cells are too healthy to die but cannot fire signals, so they enter a “hibernation” mode.
Repeated stimulation with electrical current helps the muscles of the vessel walls to relax, which lets the blood flow more freely to the cells. The blood delivers oxygen and nutrients, reactivating the hibernating or silenced neurons and allowing cognitive and vision recovery.
The authors concluded that NIBS improved cognitive and visual complications as a result of reoxygenation of the silent neurons. This was due to increased blood flow, which resulted from restored blood vessel regulation.
Speaking to Medical News Today, Keiland Cooper, Ph.D(c), a neuroscientist at the University of California, Irvine who was not involved in the study, explained, “While evidence of COVID-19 entering the brain is lacking, mounting evidence suggests that a vascular deficit may underlie many of the cognitive long COVID-19 symptoms.”
He went on to suggest the mechanism behind this “may be due to disruption of the target receptor of the virus, ACE2, which is involved in blood pressure regulation.”
Dr. Cooper commented further that “[i]n the present paper, the authors’ attempt to mitigate this deficit via brain stimulation is an interesting one.”
He cautioned, “[T]he small sample size limits the amount of conclusions to be made, however, and future work, such as controlled trials, will be needed to assess the efficacy and safety of stimulation as a possible method to mitigate symptoms.”
Dr. Bernhard Sabel, a professor of medical psychology and lead author of the study, echoes this, writing that “[c]ontrolled clinical trials are now needed to confirm our conclusion.”
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