Coffee can cause brain fog

SARS-CoV-2 causes "brain fog"

Autopsies and animal experiments show: brain cells and nerves can be affected directly - Corona uses the neuronal cell machinery to replicate

For some time now, there has been increasing evidence that SARS-CoV-2 is also a problem for the brain. Neurological symptoms were found in Covid 19 patients early in the year. A US actress who was infected with Covid-19 in the spring reported last week that she was still struggling with chronic fatigue and a strange "brain fog". Such consequences are often reported by patients in whom "classic" Covid 19 symptoms were only mildly pronounced.

A research team led by Eric Liotta from the University of Chicago speaks of a high proportion (82.3 percent) of patients who show neurological symptoms in the course of their disease. According to her observations, it tended to affect younger people. However, according to the caveat, it could be that the medical attention of older patients may have been on other problems so that neurological symptoms have been overlooked.

The German Society for Neurology (DGN) confirms the basic assumption of the last few months:

Over the past few months, we have learned that Covid-19 is not just a pulmonary disease, but that the virus attacks various organs, and in particular the brain and nervous system.

Prof. Peter Berlit, Secretary General of the German Society for Neurology

Cross reactivity

Researchers from the German Center for Neurodegenerative Diseases (DZNE) provide information that was found, among other things, in tests with mice. As a result, some antibodies bind not only to the virus, but also to the body's own structures (cross-reactivity); some of the rather immature, as yet unspecific antibodies apparently react with brain tissue. In any case, the cause for a threatening part of the after-effects of Covid-19 could lie hidden here, for example when "recovered" reports of "brain fog" months later.

In experiments with human mini-brains, so-called organoids, which are formed from neural stem cells, it was possible to determine how the coronavirus works: It also uses the ACE2 receptor for the invasion in the brain. The virus penetrates brain cells, multiplies and kills large areas of neurons. This was also shown by studies on the brains of autopsied Covid 19 patients.

The researchers describe the consequences of the neuronal infection as drastic: the human neurons in the brain organoid died off in rows. The more cells in an area were infected, the greater the rate of cell death. The surprising thing: It was not the self-infected cells that were most affected, but their immediate neighbors. The coronavirus apparently changes the environment of the infected cells and thus also triggers changes in cell metabolism in the vicinity and ultimately cell death. One of the causes: local lack of oxygen.

The proven cross-reactivity is also of concern with the subject of "vaccination". Among other things, it depends on avoiding complications and exploring possible side effects. In future vaccinations, the possible cross-reactivity with the body's own structures is therefore of great importance.

Smell disorders, a dangerous early stage?

Reports of the chemosensory disorders of the sense of smell and taste gave early indications that the nervous system could also be involved. And the numbers are high here too: According to a study published in the summer, over 85 percent of Covid 19 patients with mild to moderate symptoms from twelve European clinics reported disorders of the sense of smell and taste; In more than 10 percent of the cases, the olfactory disorders occurred in the very early stages, i.e. before any other symptoms.

Peter Berlit has therefore already called such smell and taste disorders "key symptoms (...) of infection". In animal experiments, according to Berlit, the neural path of infection - for example in MERS - has already been proven: "(...) from the nasal mucosa via free nerve endings to the brain". The viruses would presumably be passed on via synapses. "An indication that not only the olfactory nerve, but also the olfactory brain is affected, are olfactory hallucinations after the disease has subsided, which (...) German patients also report," said Berlit after a statement in the summer.

According to an early analysis from Wuhan, where the pandemic started, patients also experienced states of confusion and agitation, ataxia and clouded consciousness in addition to dizziness and headaches. A French case series also lists neurological symptoms in people with COVID-19. Of 58 patients from two Strasbourg intensive care units - patients suffering from ARDS (Acute Respiratory Distress Syndrome) as a result of COVID-19 - 49 also showed neurological symptoms.

Neuroinvasive Potential and the "Hidden Carriers"

In the current discussion about the upcoming winter, the term black box is occasionally used, which means: More or less everyone is in the dark when it comes to the number of undetected infected people ("hidden carriers") who often do not know anything about their infection themselves knowledge. Often they only have mild symptoms, which are also suppressed or glossed over.

The British ENT society already highlighted this group in a paper in spring 2020 ("Loss of sense of smell as marker of COVID-19 infection"). "I think," said one of the authors, "that these patients could be among the previously hidden carriers that have facilitated the rapid spread of COVID-19."

The good news: a disturbed sense of smell could be a recognized marker to a much greater extent to identify carriers of the virus or to induce them to be more cautious or even to self-isolate. Then, according to the British study authors, sensory disturbance would be a suitable screening tool to identify otherwise asymptomatic patients.

One would like to add: Assuming their common sense and cooperation. Because the described complications can, as described, occur in otherwise mild Covid-19 cases or even in asymptomatic infections. If you ignore the early sensory warnings and then have bad luck, the olfactory disorders do not stop there, but can lead to - even serious - long-term consequences: brain inflammation, inflammatory nerve damage and even stroke.

A conclusion: Anyone who perceives odor or taste disorders should not take the matter lightly. The upcoming season (autumn / winter 2020/21) can only benefit from everyone's prudence. (Arno Kleinebeckel)

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