- Usually associated with the brain, 95% of serotonin is produced in the gut
- Researchers from Pennsylvania believe that less serotonin may explain memory problems
- READ MORE: The risks of long Covid-19 are ‘greatly exaggerated’, research shows
Scientists think they have finally discovered the real cause of the long Covid-19.
Researchers from the University of Pennsylvania found that patients with the persistent condition have two things in common.
They have remnants of the virus in their intestines and lower levels of the ‘feel good’ hormone serotonin.
Although serotonin is often thought of in the context of the brain, 95 percent of the body’s serotonin is actually produced in the gut.
And beyond mood, it plays a crucial role in sleep, digestion, nausea, wound healing, bone health, blood clotting and libido – all of which have been affected in some way in long Covid patients.
Researchers from the University of Pennsylvania based their new statement on their previous findings that serotonin levels were lower in people with the complex condition
The scientists studied the blood of 58 patients suffering from long Covid-19, up to 22 months after their infection.
They compared this with the blood of 30 people who had no symptoms after their infection and 60 people in the early, most severe stages of Covid.
Maayan Levy, one of the lead authors of the study, told the New York Times that the amount of serotonin and other substances in the body changed immediately after infection with Covid, which also happens immediately after other viral infections.
In the long Covid group, serotonin was the only major molecule that did not return to pre-infection levels.
The researchers also examined stool samples from some of the long Covid patients and found that these contained residual particles of the virus.
Viral ‘residues’ cause the immune system to release infection-fighting proteins known as interferons.
These cause inflammation that reduces the body’s ability to absorb tryptophan, an amino acid that helps generate serotonin in the intestines.
Additionally, blood clots can form after a coronavirus infection, which can hinder how well the body can circulate serotonin.
Subnormal serotonin levels wreak havoc on the vagus nerve system, which sends signals between the brain and the body.
Serotonin also plays a role in short-term memory, so the researchers hypothesized that reduced serotonin could cause memory problems that occur with long Covid-19.
The research was published in the journal on Monday Cell.
Long Covid is defined by the World Health Organization as the development of new virus-related symptoms three months after the first Covid infection.
These symptoms can last for months to years, with doctors often wondering what causes them.
The condition includes a wide range of symptoms, such as shortness of breath, brain fog and fatigue, and depression.
The Centers for Disease Control and Prevention (CDC) estimates that one in thirteen American adultsor 7.5 percent, have long Covid.
But there is still serious debate about its true extent and severity. Several studies indicate that most people who develop the condition would suffer from the common symptoms regardless of whether they had Covid.