Mechanism behind loss of smell with COVID-19 revealed
Feb 2022, phys.org
- For more than 12 percent of COVID-19 patients, olfactory dysfunction persists
- SARS-CoV-2, indirectly dials down the action of olfactory receptors
- The new study may also shed light on the effects of COVID-19 on other types of brain cells, and on other lingering neurological effects of COVID-19 like "brain fog," headaches, and depression
- Presence of the virus near nerve cells in olfactory tissue brought an inrushing of immune cells, microglia, T cells, and cytokines that changed the genetic activity of olfactory nerve cells
- They used infected golden hamsters and olfactory tissue from 23 human autopsies [hamsters are more susceptible to nasal cavity infections]
Reminder of why it's such a big deal when you start messing with smell:
"Other work posted by these authors suggests that olfactory neurons are wired into sensitive brain regions, and that ongoing immune cell reactions in the nasal cavity could influence emotions, and the ability to think clearly (cognition), consistent with long COVID."
The talk on gene behavior and downregulation of receptor building is lost on me (not a geneticist, not a neurologist), but one of the main points I am reminded of when reading this is -- for those who experienced a change in taste or smell, for any reason, but especially after a COVID infection, long-term brain damage is possibly ongoing, but it's the kind to go undetected for another 20-30 years, depending on how old you are, of course.
They also seem to suggest that this is an explanation for why people experience brain fog, and even emotional disturbance, all of which makes a lot of sense, because your sense of smell is connected to the all those brain areas -- the hippocampus for memory and the amygdala for emotion, both integral parts of the limbic system.
via NYU Langone Health Department of Microbiology, NYU Grossman School of Medicine and Columbia University: Marianna Zazhytska et al, Non-cell autonomous disruption of nuclear architecture as a potential cause of COVID-19 induced anosmia, Cell (2022). DOI: 10.1016/j.cell.2022.01.024
WHERE CAN I GET MORE INFORMATION ON SMELL LOSS?
Monell Anosmia Project - US Organization studying smell and taste
AbScent - UK Organization raising public awareness of smell loss
National Institute on Deafness and Other Communicable Disorders (NIDC) - Smell Disorders
ENT UK - Loss of Smell as Marker of Covid-19 Infection
- How Covid-19 can damage the brain - BBC Future, June 2020. https://www.bbc.com/future/article/20200622-the-long-term-effects-of-covid-19-infection
- Trying to Make Sense of Long COVID Syndrome, Dr. Francis Collins. NIH Director's Blog, January 19th, 2021. https://directorsblog.nih.gov/
- What Makes a Better Smeller? Asifa Majid, Laura Speed, Ilja Croijmans, et al. Sage Pub., Jan 2017, volume 46 issue pp 406-430. https://doi.org/10.1177/0301006616688224
- Monell Center Scientists Find that Insulin is Necessary for Repairing Olfactory Neurons: Findings Point to Possible Treatment for Smell Loss, May 2021. https://monell.org/monell-center-scientists-find-that-insulin-is-necessary-for-repairing-olfactory-neurons-findings-point-to-possible-treatment-for-smell-loss/
- via Children's Hospital Boston: Laura Montefusco et al, Acute and long-term disruption of glycometabolic control after SARS-CoV-2 infection, Nature Metabolism (2021). DOI: 10.1038/s42255-021-00407-6. http://dx.doi.org/10.1038/s42255-021-00407-6