Among the long-term consequences of Covid, structural alterations in the brain were observed after anosmia. The most common are more impulsive behaviors in decision-making.
Research into the long-term consequences of Covid reveals that people who lost their sense of smell during the acute phase of the infection now suffer from structural alterations in the brain, which is particularly evident in a specific behaviour: being more prone to impulses when making decisions.
Since the beginning of the SARS-CoV-2 pandemic, evidence has accumulated that some recovered patients show cognitive impairment and brain alterations. Studies have found that even months after recovery, some people continue to experience neurological, psychiatric and cognitive effects. Other studies suggest that vaccination remains a weapon to cushion these consequences.
“Despite the growing body of evidence, specific clinical factors associated with brain alterations remain elusive, presenting challenges in identifying populations at risk of developing long-term brain and cognitive impairment after SARS-CoV-2 infection,” says a paper published in the journal Scientific Report, which has taken a step forward in this regard.
The work, whose evidence is based on a “laboratory game” in which participants had to make a series of choices under certain premises, was carried out by researchers from the Center for Studies in Human Neuroscience and Neuropsychology at the Diego Portales University in Chile, and published in Nature.
“The severity of acute infection is the most studied clinical factor leading to brain and cognitive impairment. A longitudinal cohort study has revealed that the severity of the acute episode correlates with cognitive impairment in long-term follow-up,” the research adds.
Patients who experienced a severe episode and exhibited neurological symptoms during the infection showed cognitive impairment and brain changes one year after infection. Even patients with mild Covid also show subtle brain changes, experts say.
Consequences of loss of smell
Regarding the loss of smell, the researchers note that “anosmia is a commonly reported symptom in patients with Covid-19 that frequently occurs early in the course of the disease and may persist as a long-term symptom. It has been suggested that SARS-CoV-2 infection causes the death of supporting cells in the olfactory epithelium, with consequences for neuronal function. This mechanism aligns with the rapid onset of anosmia in Covid-19 and its rapid recovery after regeneration of supporting cells.”
“Our findings indicated that both hospitalization and anosmia had differential impacts on behavior in a cognitive flexibility task. However, only anosmia was consistently correlated with alterations in brain function across several parameters, including functional activity, cortical thickness, and white matter integrity (fibers of neurons that connect and transmit impulses to others), alterations associated with mood changes, more impulsive behaviors, and decision-making deficits.”
“While no differences were observed in our cognitive screening assessment, intriguing patterns emerged in performance on the behavioral task. All participants displayed adaptive behavior during the game. In particular, the distinctive decision-making strategy observed in patients with anosmia was characterized by more impulsive option switches,” they concluded.
Neurologist Conrado Estol, consulted on the subject, framed this picture within what is called long Covid or “Long Covid”: “Long Covid is a great challenge for the world, for human health, for health systems and the global economy. There are about 400 million people affected in the world and the cost of treating these people would be one trillion dollars (1% of the global economy). These patients can have any organ in the body affected. We are still far from having a biomarker. Several have been evaluated and none define who specifically has this form of long Covid and there is no approved treatment either, although there are several under evaluation.”
He then focused on the object of study of the published work: “The brain is one of the most affected organs. The mechanism is complex because inflammatory cells and substances are activated that alter the function of brain tissue and produce damage with inflammation of the neurons and activation of the cells that are located between the neurons and that harms the neurons. In addition, a relationship is activated between the adrenal gland and the cortisol generated by that gland, with an effect on the brain.”
In the research, they observed that patients who had loss of smell during Covid “have altered responses and this is manifested by impulsiveness and difficulty in decision-making, functions that belong to the frontal lobe in what is called executive function, which is what allows us to organize and carry out actions,” Estol explained.
Finally, the expert added that “patients, whether they had moderate or severe disease, when they presented loss of smell – confirming that the virus had entered the brain and affected this sense – evidently when conducting more sensitive cognitive studies, the researchers detected that they had not only lost their sense of smell, but that they had altered behaviors, which reflects that the brain damage had been more extensive.”
(Clarion)
