By prolonged COVID, long COVID or post-COVID syndrome, specialists understand the set of symptoms and signs that account for affections in organs that go beyond the respiratory system and that are characteristic of the systemic inflammatory picture that causes SARS-CoV-2 in the body.
Feeling of confusion and bewilderment, difficulty concentrating, slow processing of thoughts, memory problems are some of the symptoms most reported by patients to whom specialists around the world try to explain and understand, in order to give better treatment.
And while at the moment little is known about “mental fog”, a literal translation of English brain fog, which affects a significant part of patients after the COVID-19 picture, the symptoms, according to experts, are not much different from those experienced by those who undergo a chemotherapy treatment to treat a tumor, as well as those suffering from chronic fatigue syndrome, Alzheimer's and other post-viral disorders.
According to research published in the scientific journal Nature, the neurological inflammation underlying these disorders may in fact be a common explanation.
Researchers at Oxford University studied the changes that occurred at the brain level in 785 participants in a large British study, and observed “a greater reduction in gray matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus, greater changes in markers of tissue damage in regions functionally connected to the primary olfactory cortex, and greater reduction in overall brain size. The infected participants also showed, on average, greater cognitive decline between the two time points,” as the researchers reported in the publication.
For the work, which involved people between the ages of 51 and 81, the experts took brain images of patients twice, including 401 cases that tested positive for SARS-CoV-2 infection between their two scans, with 141 days on average separating their diagnosis and the second scan and 384 controls. And they acknowledged the difficulty of not having pre-infection imaging data, which “reduces the likelihood that pre-existing risk factors will be misinterpreted as effects of the disease.”
What happens in other similar inflammatory mechanisms
“To date, the mechanisms that link the virus to the manifestation of cognitive fog are not fully understood. Most of the studies carried out so far are small, that is, they concern a few people, and the data are preliminary: as with everything related to COVID and its long-term consequences, we still have many questions and few answers.” Valentina Di Mattei is a professor at the Faculties of Psychology and Medicine at Vita-Salute San Raffaele University and acknowledged: “We don't know enough to be able to draw definitive conclusions. The truth is that, like this latest study in Nature, other research has now also found similarities between post-COVID brain fog and the symptoms experienced by patients who do chemotherapy for cancer.”
According to experts, similarities were also found with multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease and other postviral syndromes after infections with influenza, Epstein-Barr, HIV or Ebola viruses. “The analogy is based on the analysis of seemingly similar inflammatory processes,” the expert clarified. Also according to the conclusions of Oxford researchers, it could be a neuroinflammation caused by SARS-CoV-2 infection to explain the brain opacity that affects so many people.”
It has now been widely demonstrated that chemotherapy drugs for the treatment of cancer, over time and gradually, have repercussions on patients' cognitive abilities, creating a kind of mental fog, a condition known as chemo-brain. This disorder mainly leads to memory difficulties, reduced concentration, increased difficulty multitasking and slow thinking.
In the words of Di Mattei, “the impact on quality of life can be strong and the problem worries 15-20% of people who undergo chemotherapy. It appears during treatment, but can persist for years. The most recent studies highlight a deterioration of microglia, a set of brain cells that protect the brain from inflammation, just as this new British study in post-COVID patients also seems to emerge. Brain opacity in patients who are infected with SARS-CoV-2 is very similar with difficulties in concentration, logic, problem solving and a drop in memory.”
The outlook for the future
According to specialists, until the mechanisms that cause brain opacity are clear, it is difficult to give answers to the most common questions: how long does the problem last and how is it treated?
It takes time to get indications and it is not yet known whether the damage will resolve itself or give people greater vulnerability. Research recently published in the European Journal of Neurology by researchers from the University of Milan, the ASST Santi Paolo e Carlo and the Italian Auxological Institute indicates, for example, that, after a year, the mental fog of COVID decreases but does not disappear. The study was conducted in a group of 76 patients admitted to the ASST Santi Paolo e Carlo and underwent different oxygen therapies depending on their severity: 63% of patients experienced cognitive deficits five months after hospital discharge and the disorder persisted even after 12 months in 50% of those affected.
Regarding treatments, specialists agree that they must be personalized to the individual, taking into account what disorders they suffer from and what other pharmacological treatments they are following, either due to the physical and mental consequences of the coronavirus or other pathologies.
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