June 11, 2020

Three Stages of Brain Impairment Caused by COVID-19 Identified

Neurologists have published a comprehensive review of the effects of coronavirus disease 2019 (COVID-19) on the nervous system, which classifies brain damage caused by the virus into 3 stages.

The findings of the study, published in The Journal of Alzheimer’s Disease, encourages the adoption of a 3-stage classification, calls for more research on the long-term effects of COVID-19 on the brain, and stresses the need for patients to receive a brain MRI before leaving the hospital.

“We are learning that a significant number of hospitalised patients with COVID-19 have various degrees of brain impairment,” said Majid Fotuhi, MD, NeuroGrow Brain Fitness Center, Greensboro, Virginia. “As a medical community, we need to monitor these patients over time as some of them may develop cognitive decline, attention deficit, brain fog, or Alzheimer’s disease in the future. There is a lot we can do to promote brain healing in patients with COVID-19, but first we must understand the nature and severity of their neurological deficits. At the patient level, getting a baseline MRI before leaving the hospital is imperative so that we have a starting point to evaluate and treat them.”

The paper proposes the adoption of a 3-stage “NeuroCovid” classification scheme to provide a basis from which to build on future hypotheses and investigations regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the nervous system. These stages include:
● NeuroCovid Stage 1: The virus damage is limited to epithelial cells of nose and mouth and the main symptoms include transient loss of smell and taste.
● NeuroCovid Stage 2: The virus triggers a flood of inflammation -- the cytokine storm -- which begins in the lungs and travels in the blood vessels throughout all body organs. This cytokine storm leads to the formation of blood clots which cause small or large strokes in the brain.
● NeuroCovid Stage 3: An explosive level of cytokine storm damages the blood brain barrier, the protective insulation layer in blood vessels of the brain. As a result, blood content, inflammatory markers, and virus particles invade the brain and patients develop seizures, confusion, coma, or encephalopathy.

“This review, while presenting what is currently known about this virus and the related clinical neurology, represents only the base of what will eventually become a separate active field of research,” the authors wrote. “Much work remains to determine a fuller understanding of the underlying neurobiology of COVID-19. These include better characterised COVID-19 cohorts with longitudinal follow ups. Standardised evaluations such as quantitative EEG, fluid biomarkers, cognitive evaluations, and multi-modal neuroimaging can also lend insight to possible long-term neurological sequelae in COVID-19 such as depression, memory loss, mild cognitive impairment, or Alzheimer’s disease.”

Reference: https://content.iospress.com/articles/journal-of-alzheimers-disease/jad200581

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