For a long time now we have been accustomed to hearing about COVID-19 every day (and rightly so), about the respiratory problems it can cause, up to the infamous deaths.
Although the most common problems mainly concern fever, cough and difficulty in breathing, there is one aspect that is little mentioned but for which there is a lot of research: cognitive deficits.
The presence, in fact, of anosmia (loss of smell) and ageusia (loss of taste) has focused attention on possibility that the disease directly or indirectly affects the central nervous system as well.
Given, as already mentioned, theimportant presence of studies that have evaluated the presence of cognitive deficits in people affected by COVID-19, a group of scholars conducted a review of the current literature on the subject to summarize the most salient data currently available.
What has emerged?
Although with many limitations linked to the heterogeneity of the research conducted so far (for example, differences in the cognitive tests used, diversity of samples for clinical characteristics ...), in the aforementioned review interesting data are reported:
- The percentage of patients with impairments also on the cognitive level would be very consistent, with a percentage that varies (based on the studies carried out) from a minimum of 15% to a maximum of 80%.
- The most frequent deficits would concern the attentional-executive domain but there are also researches in which the possible presence of mnemonic, linguistic and visual-spatial deficits emerges.
- In line with pre-existing literature data, for the purposes of a global cognitive screening, even for patients with COVID-19 the MoCA would be more sensitive than the MMSE.
- In the presence of COVID-19 (even with mild symptoms), the likelihood of also having cognitive deficits would increase by 18 times.
- Even after 6 months of healing from COVID-19, about 21% of patients would continue to show cognitive deficits.
But how are all these deficits possible?
In the study just summarized, the researchers list four possible mechanisms:
- The virus can reach the CNS indirectly through the blood-brain barrier and / or directly by axonal transmission through olfactory neurons; this would lead to neuronal damage and encephalitis
- Damage to brain blood vessels and coagulopathies that cause ischemic or hemorrhagic strokes
- Excessive systemic inflammatory responses, "cytokine storm" and peripheral organ dysfunction affecting the brain
- Global ischemia secondary to respiratory failure, respiratory treatment and so-called acute respiratory distress syndrome
COVID-19 should be taken seriously also for the possible cognitive deficits it can cause, above all because these appear very frequent and would also affect people who have had forms of the disease with mild symptoms, also bearing in mind the high persistence of the previously mentioned neuropsychological compromises.
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- Ciesielska, N., Sokołowski, R., Mazur, E., Podhorecka, M., Polak-Szabela, A., & Kędziora-Kornatowska, K. (2016). Is the Montreal Cognitive Assessment (MoCA) test better suited than the Mini-Mental State Examination (MMSE) in mild cognitive impairment (MCI) detection among people aged over 60? Meta-analysis. Psychiatr Pol, 50
- Daroische, R., Hemminghyth, MS, Eilertsen, TH, Breitve, MH, & Chwiszczuk, LJ (2021). Cognitive impairment after COVID-19-a review on objective test data. Frontiers in Neurology, 12, 1238.