Olfactory dysfunction in COVID-19: pathology and long-term implications for brain health

Decreased smell function is related to brain health, future mortality, and quality of life. Most people inflicted with the SARS-CoV-2 virus evidence some measurable smell dysfunction during its acute phase, although many are unaware of the loss. Long-term deficits occur in up to 30% of COVID-19 cases, although total anos-mia is relatively rare. This review explores what is presently known about the nature and pathophysiology of olfactory dysfunction due to the SARS-CoV-2 virus, including reversible inflammation within the olfactory cleft, downregulation of olfactory receptor proteins, and long-lasting peripheral and central damage to olfactory structures. It also addresses the question as to whether long-term smell loss might increase the likelihood of future development of cognitive and neuro-logical deficits.

Automated summary

Decreased smell function is associated with brain health, mortality, and quality of life. Most COVID-19 patients experience some degree of smell dysfunction during the acute phase, with many being unaware of the loss. Long-term olfactory deficits occur in up to 30% of cases, but total anosmia is relatively rare. This review examines the nature and pathophysiology of olfactory dysfunction caused by the SARS-CoV-2 virus, including reversible inflammation in the olfactory cleft, downregulation of olfactory receptor proteins, and persistent damage to olfactory structures. It also addresses whether long-term smell loss may increase the risk of future cognitive and neurological deficits.