Century of Data shows COVID-19 likely to affect the brain in the long run

The international consortium funded by the Alzheimer’s Association will study the effects.

An article published this month in alzheimer & Dementia: The Journal of the Alzheimer’s Association cites decades of published scientific evidence to provide a convincing argument SARS-CoV-2Expected long-term effects on the brain and nervous system.

Researchers in dementia at the University of Texas Health Science Center in San Antonio (UT Health San Antonio) are the first and leading authors of the report and are joined by co-authors from the Alzheimer’s Association and the universities of Nottingham and Leicester in England.

“Since the influenza pandemic of 1917 and 1918, many similar diseases have been associated with brain disorders,” said lead author Gabriel A. de Erausquin, MD, PhD, MSc, professor of neurology in Joe R. and Teresa Lozano. Long School of Medicine at UT Health San Antonio. “These respiratory viruses included H1N1 and SARS-CoV. The virus that causes SARS-CoV-2 COVID-19, is also known to have an impact on the brain and nervous system. ”

Gabriel de Erausquin

Gabriel de Erausquin, MD, PhD, MSc, is a researcher in dementia at the University of Texas Health Science Center in San Antonio. He is a researcher at the Glenn Biggs Institute of the University for Alzheimer’s and Neurodegenerative Diseases. Dr. de Erausquin is the lead author in a historical perspective that shows that decades of research indicate the association of flulike respiratory viruses such as COVID-19 with effects on the brain and nervous system. Credit: UT Health San Antonio

Dr. de Erausquin, an investigator at the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases at UT Health San Antonio, said it is clear that the damage caused by the pandemic will not be limited to acute effects, such as hospital delirium, but will have chronic consequences that affect the quality of life and independence of many individuals.

The question is to what extent and in what form. Even mild COVID-19 infections can have long-term negative effects on the brain, said Dr. De Erausquin.

“As the article Alzheimer’s and Dementia points out, the under-recognized medical history of these viruses in the last century suggests a strong link to brain diseases that affect memory and behavior,” said Maria C. Carrillo, PhD, head of Alzheimer’s Association Science and a co-author on paper. “At this difficult time, we can create a ‘silver lining’ by leveraging the Alzheimer’s Association’s global coverage and reputation to bring the research community together to illuminate the long-term impact of COVID-19 on the brain.”

International emergency study

The Alzheimer’s Association funds the initial work of a consortium of experts from more than 30 countries to understand how COVID-19 increases the risk, severity, rhythm and progression of neurodegenerative diseases such as Alzheimer’s and psychiatric diseases, including depression. Consortium members will enroll selected study participants from a group of millions of confirmed cases of COVID-19 documented in hospitals around the world. A second group of entrants will consist of people participating in existing international research studies. Participants will be evaluated in a series of measures at their initial appointment and again at six, nine and 18 months. These measures include knowledge, behavior and, where possible, brain volumes measured by magnetic resonance imaging.

Infiltration into the brain

It is known that coronavirus enters cells through receptors called ACE2. The highest concentration of ACE2 receptors is in the olfactory bulb, the structure of the brain involved in the sense of smell.

“The basic idea of ​​our study is that some of the respiratory viruses have an affinity for nervous system cells,” said lead author Sudha Seshadri, MD, a professor of neurology at UT Health San Antonio’s Long School of Medicine and director of the Glenn Biggs Institute. . Olfactory cells are very susceptible to viral invasion and are particularly targeted by SARS-CoV-2, and therefore one of the prominent symptoms of COVID-19 is odor loss.

The olfactory bulb connects to the hippocampus, a brain structure primarily responsible for short-term memory.

“Traces of the virus, when they invade the brain, lead almost directly to the hippocampus,” said Dr. De Erausquin. “It is believed that this is one of the sources of cognitive impairment observed in patients with COVID-19. We suspect that it could also be part of the reason why there will be an accelerated cognitive decline over time in susceptible individuals. ”

The authors point out that:

  • Intranasal administration of SARS-CoV-2 to mice results in rapid brain invasion.
  • Headache, hypogeusia (reduced ability to taste) and anosmia (loss of odor) appear to precede the onset of respiratory symptoms in most affected patients.
  • SARS-CoV-2 can be found in the post-mortem brain.
  • Abnormal brain imaging that can be characterized by the appearance of lesions in different regions of the brain – and the appearance of other abnormal changes in the brain that can influence the clinical presentation – has emerged as a major feature of COVID-19 in all parts of the world.
  • Abnormal imaging was observed in an individual whose only symptom was loss of smell.

The study will collect information over the next two to three years. Initial results are expected in early 2022 for the first set of evaluations. The consortium is assisted by technical guidance from the World Health Organization.

Reference: “Chronic Neuropsychiatric Sequelae of COVID – 19: The Need for a Prospective Study of Viral Impact on Brain Function” by Gabriel A. de Erausquin, Heather Snyder, María Carrillo, Akram A. Hosseini, Traolach S. Brugha, Sudha Seshadri and the CNS consortium SARS – CoV – 2, 5 January 2021, Alzheimer’s and dementia: Journal of the Alzheimer’s Association.
DOI: 10.1002 / alz.12255