Previously unknown corona episode: how an infection can affect the flow of speech

What a new study from Germany shows is quite concerning. The researchers from Augsburg examined the brain function of 372 people who were infected with Corona on average nine months ago and therefore did not have to go to hospital. Several cognitive tests showed: 41 percent suffered from mild memory problems (6 percent of the clear) and 12 percent had mild speech fluency disorders (5 percent of the severe).

This study is one of many studies of the effects of Covid-19 on the brain. It should be taken with caution: In this somewhat older group of study participants (mean age 48), half had at least one pre-existing condition such as high blood pressure, diabetes, depression and more. In addition, brain performance was compared to the known population mean at the appropriate age – not to pre-infection results. The participants were also ill in 2020 and therefore not vaccinated.

One thing is certain: neurologists have more to do since the pandemic. For example, the long Covid consultation hours at Inselspital Bern have seen a significant increase in patients with neurological problems and the waiting time is still four to five weeks.

Clinic director and chief physician of the Inselspital, Claudio Bassetti, is not surprising. He says: “The nervous system is relatively commonly affected by Covid-19 and word-finding disorders are not that rare.” The neurologist has published more than 20 studies on the neurological effects of the pandemic. As president of the European Academy of Neurology, he founded an international neuro-Covid-19 working group.

A Covid-19 infection can rarely cause dementia or “unmask” Alzheimer’s disease, says Bassetti. Some studies have shown a decrease in gray matter in the brain after a corona infection, which could explain these associations.

But usually the symptoms don’t get worse. Bassetti says: “We often see an improvement in neurological disorders, and the mild ones in particular tend to disappear. Most people feel better after three to six months.”

A more recent study, which looked at long-term symptoms after Corona, also shows an improvement in cognitive problems after six to 12 months – albeit less clearly compared to other symptoms such as breathing problems and fatigue. Only smell and taste disorders are more pronounced after six to twelve months.

If you don’t notice any cognitive problems and you feel completely recovered after Corona, you probably are. At least that is the conclusion of a March 2022 review study from England, published in “Frontiers”: The brain performance of those who felt fully recovered was no different from those who were never infected.

In contrast, self-perceived symptoms correlated strongly with poorer performance on memory tests, especially those involving verbal memories. “Specific problems with language and verbal memory are consistent with the frequency of self-reported deficits in these areas of Long Covid – and with the results of gray matter loss in the left hemisphere,” the authors write.

However, in December, a new review study in ‘Frontiers’, which looked only at studies in which the brain was always scanned, concluded that post-Covid-19 lasting memory impairment had not yet been demonstrated and that most symptoms were related to disappearing over time. . The volume of the cerebral cortex also recovered after ten months.

The causes of cognitive problems after a Covid-19 infection are diverse. And especially brain scans are often unremarkable. Direct brain infection by the virus is quite rare. According to Bassetti, the most common cause of post-Covid-19 neurological disease is intense systemic inflammation, which makes the blood-brain barrier more permeable and also has detrimental effects on the nervous system. “These processes can only be assumed in living people, but they have been detected in the brains of deceased patients,” says Bassetti.

Another cause may be so-called megakaryocytes. These are precursors of thrombocytes, ie platelets, which can help the blood to clot. After Covid-19, they could impede blood circulation and thus the oxygen supply in the brain, as elsewhere in the body. English researchers found megakaryocytes in the brains of five deceased patients who had corona – but none in two brains of deceased uninfected people. The researchers speculate that the so-called brain fog with impaired concentration could originate from the megakaryocytes. Strokes and cerebral thrombosis after Corona, on the other hand, are rare.

Incidentally, the research from Augsburg mentioned at the outset showed that people with cognitive problems often also had depression. It is well known that depression is often accompanied by cognitive problems. Both may be related to inflammatory processes in the brain. In the Inselspital in Bern, psychologists are always consulted for neurocognitive problems. “The factors are hard to discern,” says Bassetti, “but even if there are psychological causes, that doesn’t mean nerve damage hasn’t occurred in the brain.” (aargauerzeitung.ch)