A study points out that coronavirus infection can cause neuroinflammation and lead to progressive degenerative pictures; for specialists, this is one of the worst sequelae of the disease.
More than a year and a half after the first registration of the Covid-19 in China, scientists are making progress in discovering the effects of coronavirus infection, such as an increased propensity for episodes of thrombosis, stroke, kidney and heart failure, and pulmonary fibrosis. Now, a new concern joins the list of possible sequelae: the neurological effects of the disease, with the development of dementias, especially in critically ill patients. A study by the academic medical center Cleveland Clinic, in the United States, published in the medical journal “Alzheimer’s Research & Therapy”, points out that Sars-CoV-2 is capable of causing neuroinflammations similar to those caused by Alzheimer. To reach this conclusion, the research genetically evaluated individuals who have the disease and were not infected by the coronavirus, as well as people who do not have dementia and tested positive for Covid-19. From this, it was possible to identify the proximity between the genes/proteins of the coronavirus and those associated with several neurological diseases, as well as to establish the similarities between both diseases. “These findings indicate that the virus can impact several genes or pathways involved in neuroinflammation and microvascular brain damage, which can lead to cognitive impairment similar to Alzheimer’s disease,” said Feixiong Cheng, lead author of the study and member of the Institute of Genomic Medicine of the Cleveland Clinic.
In addition to highlighting the relationship between the proximity of coronavirus genes/proteins and neurological diseases, the Cleveland Clinic study also shows that proteins present in Sars-CoV-2 allow the virus to cross the blood-brain barrier (a structure that blocks the entry of substances from the blood to the central nervous system), leading to the emergence of neurological complications. However, neurosurgeon Márcio Rassi points out that several factors also influence the development of dementia, and Covid-19 is not an isolated factor to trigger it. “Older patient, long ICU stay, use of sedatives because he was intubated, mechanical ventilation, all of this, associated with the risk caused by Covid-19, contributes for him to develop a post-infection cognitive or neuropsychiatric disorder. And the opposite is also true: patients with dementia are at greater risk of developing more severe cases of Covid”, highlights Rassi, who is secretary of the skull base department of the Brazilian Society of Neurology.
The neurosurgeon points out that, in addition to causing dementia similar to Alzheimer’s, Covid-19 can also lead to the emergence of other neurological effects, such as loss of smell — one of the most common sequelae —, mental confusion, headache persistent e memory loss. However, it is possible to say that dementia is among the worst effects of the disease, as it is irreversible. “Dementia is a progressive degenerative disease that, in the long term, decreases a person’s cognitive function. That is, memory, reasoning and even language. The person deteriorates, but we cannot cure it. We managed to hold the progression of some symptoms with medication, but not reverse it”, points out the doctor, noting that a dementia such as Alzheimer’s affects other people besides the patient. “Since the disease is progressive, the person needs more and more from others. In the beginning, help with food, a purchase… Then, to change, go to the bathroom, for basic care. This is getting worse and demanding from everyone around. It is a disease that affects a large number of people. So, dementia ends up being one of the worst sequels of Covid-19”, he adds.
Márcio Rassi clarifies, however, that it is necessary to know how to differentiate which symptoms can represent the beginning of a degenerative disease and which ones are caused by other factors, such as the pandemic context itself. “Many people arrive at the office and say: ‘I’m too forgetful.’ But forgetting is going to the kitchen and not remembering what I was going to do. This is normal, it’s overload. Forgetting the name of an acquaintance you haven’t seen for a long time is normal, but finding a relative you’re familiar with and not remembering the name is something that draws attention. Thinking about Alzheimer’s, the initial change is in recent memory, that’s why people who have the disease think that deceased acquaintances are alive, but they don’t recognize their grandchildren. Recent memory is impaired, but old memory is retained. This is characteristic of Alzheimer’s disease. If you notice any kind of unusual behavioral change it can be a warning sign.”
In addition to demonstrating that Covid-19 may be related to the onset of dementias, the Cleveland Clinic research also pointed out that individuals with the AD APOE E4/E4 risk allele, a genetic trait that determines the propensity for Alzheimer’s, have lower antiviral defenses, which suggests a higher risk of infection with coronavirus. An analysis of data from 236,379 patients, published in the scientific journal “The Lancet Psychiatry”, also revealed that 1 in 3 infected with Covid-19 received a diagnosis of neurological effect six months after the infection. Among the incidences presented are cases of intracranial hemorrhage, Parkinson’s, anxiety disorder and psychotic disorder, as well as dementia. Other studies mentioned by the researchers indicate that cases of neurological sequelae are not limited to Sars-CoV-2. According to the study, 20% of people who had Severe Acute Respiratory Syndrome (Sars-CoV-1) in 2002 and Middle East Respiratory Syndrome (MERS) in 2012 had ongoing impairment of memory, with effects neurocognitive.