Long Covid could be due to after-effects on various organs or to neurological damage to the brain.
- A new study explains that long Covid could be due to the after-effects caused by the virus on various organs.
- Other work suggests that it is damage to the brain, more precisely to the neurons regulating reproductive functions, which explains long Covid.
- In France, two million patients are still suffering from long-term Covid more than three months after infection.
The more research progresses, the more researchers understand why some patients have long Covid and not others. Recently, two new studies were published that provide new information about this disease. For one, the causes of long Covid come from organic after-effects and for the other, neurological ones.
After-effects on various organs
The first study, published in the journal Lancet Respiratory Medicine, shows that long Covid is due to the after-effects suffered by different organs after infection with the virus. There is “concrete evidence that different organs undergo changes”, explains Christopher Brightling, co-author of this work.
To reach this conclusion, scientists analyzed the MRIs of 259 patients who were hospitalized due to Covid-19 in 2020 and 2021. By comparing them to MRIs of people who were not infected with the virus, the researchers observed that almost a third of the patients had after-effects on various organs several months after the infection and their discharge from the hospital.
The organs affected include the lungs, kidneys, heart and liver. Scientists also observed that the white matter of the brain was sometimes affected, which could be linked to a slight cognitive decline in the patient. According to the researchers, the causes of long Covid could therefore come from these lesions on different organs rather than from a single lesion.
Neurological lesions in the brain involved
Another research team focused on the brain. Their work, published in the journal eBiomedicine, highlight a new cause of long Covid. The disease damages certain neurons regulating reproductive functions.
Patients whose neurons were affected experienced a drop in testosterone (a sex hormone) and reported more problems with memory, attention, and difficulty concentrating than others. These results, “suggest that the infection can lead to the death of these neurons and be the cause of certain symptoms that persist over time”explains a press release from the National Institute of Health and Medical Research (Inserm).
In France, 30% of people who had a SARS-CoV-2 infection more than three months previously – or two million patients – would still suffer from one or more symptoms of long Covid, according to a study carried out by Public health France. The most common are cough, shortness of breath, fatigue, loss of taste or smell, fever, etc.