• Persistent post–COVID-19 smell loss is associated with immune cell infiltration and altered gene expression in olfactory epithelium – “These findings indicate that T cell–mediated inflammation persists in the olfactory epithelium long after SARS-CoV-2 has been eliminated from the tissue, suggesting a mechanism for long-term post–COVID-19 smell loss.”
  • 18F-FDG brain PET hypometabolism in patients with long COVID – “This study demonstrates a profile of brain PET hypometabolism in long COVID patients with biologically confirmed SARS-CoV-2 and persistent functional complaints more than 3 weeks after the initial infection symptoms, involving the olfactory gyrus and connected limbic/paralimbic regions, extended to the brainstem and the cerebellum. These hypometabolisms are associated with patients’ symptoms, with a biomarker value to identify and potentially follow these patients. The hypometabolism of the frontal cluster, which included the olfactory gyrus, seems to be linked to ACE drugs in patients with high blood pressure, with also a better metabolism of this olfactory region in patients using nasal decongestant spray, suggesting a possible role of ACE receptors as an olfactory gateway for this neurotropism.”
  • Long COVID Neuropsychological Deficits after Severe, Moderate, or Mild Infection – “This study demonstrates the presence of long-term neuropsychological sequelae following SARS-CoV-2 infection, regardless of the severity of the respiratory disease in the acute phase. Some of the cognitive deficits could be explained by psychiatric variables, emphasizing the importance of considering a broad range of psychiatric symptoms. However, not all neuropsychological sequelae could be explained by these variables. The presence of correlations between olfaction, emotion recognition, and episodic memory, which share common functional and anatomical substrates, reinforces the hypothesis that the virus targets the CNS (notably the limbic system). Finally, the data support the notion of different clinical phenotypes, paving the way for clinical guidelines and recommendations for the management of long-term neurological impairment following SARS-CoV-2 infection.”