Long Covid patients often have low serotonin levels. So too little of the hormone known for happiness and well-being. But that’s just one function: serotonin is also responsible for regulating body temperature, the sleep-wake rhythm, regulating appetite and constricting blood vessels.
And apparently serotonin plays an important role in Long Covid. In a study published in October in the journal ‘Cell’, American researchers led by Andrea C. Wong showed that serotonin levels in the blood can be used to determine whether a person who has recovered from Corona still has persistent complaints. has. The researchers measured very different metabolic breakdown products and compared Long Covid patients with those who had recovered without symptoms. Only the serotonin level stood out so clearly that it could be seen whether someone belongs to the Long Covid group.
This alone is a remarkable success, because so far there is no easily measured marker in the blood to reliably diagnose Long Covid. It is known that Long Covid patients also have significantly reduced cortisol levels, but it is not entirely certain whether this was not the case before the infection and whether Long Covid preferred this.
At the beginning of November, a new study appeared in the journal ‘Nature’, which also gives hope for drug therapy via the serotonin mechanism: Dutch researchers led by Carla P. Rus showed that two-thirds of a group of 95 ‘Long Covid’ patients got better after receiving serotonin reuptake inhibitors (SSRIs).
Two-thirds showed a good to strong improvement, a quarter showed little improvement and 10 percent reported no effect. These are “promising data” for the disease Long Covid, as Dominique Braun, senior doctor at the Clinic for Infectious Diseases of the University Hospital Zurich and head of the outpatient Long Covid consultation, puts it.
The weak point of the study: it has no control or placebo group. In addition: 61 participants had already started treatment and therefore had to remember their condition before taking the medication – which poses a risk of misjudgment. Braun therefore says: “You should not overestimate this research. The results must now first be repeatable.”
If the effect were confirmed – even to a lesser extent – it would be good news that those affected have been waiting for years. Serotonin reuptake inhibitors are also readily available medications: they are among the most common antidepressants.
But does this mean that Long Covid is a mental illness and not a physical illness? It depends on how you define mental illness. In any case, the mechanism of action is physical: the researchers assume that the serotonin reuptake inhibitors have a biochemical effect on various neurotransmitter systems and on the immune system.
They suspect that the most important pathway is kynurenine metabolism, which works intensively with the immune system. In people with Long Covid, this metabolism is hyperactive and promotes inflammation. This causes a deficiency of the precursor tryptophan. But because serotonin metabolism also needs tryptophan, it is also affected and does not get enough of it.
The researchers suspect that this deficiency occurs during the infection because the spike protein of the coronavirus attacks a receptor in the intestine through which tryptophan is absorbed. The more noticeable such breakdown substances are in the blood, the more serious the cognitive problems of Long Covid patients.
However, drugs containing serotonin reuptake inhibitors make serotonin more available to the neurons, which can compensate for some of the deficiency. And SSRIs reduce oxidative stress. Because the effect of the medication persisted even after six months, the researchers suspect that these antidepressants also address the cause of the problem and dampen the hyperactive kynurenine metabolism in Long Covid. The therapy appears to work less well in the most severe form, chronic fatigue ME/CFS.
A case study by two British researchers this spring had already pointed out that SSRI antidepressants could be useful: one patient recovered after treatment with three different blood thinners, including Sertraline – a serotonin reuptake inhibitor. Sertraline not only has an anti-inflammatory effect, but also helps prevent clotting by binding to the spike protein unit S1.
But the various explanation attempts also show that we do not know exactly how antidepressants affect the brain, immune system, metabolism and blood vessels. The authors of the Dutch study write in their conclusion: “Our hypothesis is that in many Long Covid symptoms the neurotransmitter systems are not damaged – but are disrupted by a tryptophan deficiency and overactive kynurenine metabolism.”
In practice, serotonin reuptake inhibitors are still usually prescribed to Long Covid patients due to accompanying depressive symptoms. Dominique Braun from the Long Covid Consultation says: “We sometimes prescribe them, but not specifically for Long Covid symptoms. We haven’t gotten that far yet, but we are discussing it internally to see if we can offer the therapy systematically.” Because at the moment we don’t really have anything to offer patients at the drug level.
A little further away is Rehab Basel. The head of neurology and Long Covid specialist there, Margret Hund-Georgiadis, says: “This is a very good study, we actually use the drug often, if only because of the depressive development due to the disease, and we also have good experiences.” (aargauerzeitung.ch)
Source: Blick
I am Ross William, a passionate and experienced news writer with more than four years of experience in the writing industry. I have been working as an author for 24 Instant News Reporters covering the Trending section. With a keen eye for detail, I am able to find stories that capture people’s interest and help them stay informed.
