The depressed mood or anxiety manifested in COVID-19 patients may perhaps be a sign that the virus affects the central nervous system, according to an international study conducted by a researcher at the University of Cincinnati.
These two psychological symptoms were more closely associated with a loss of smell and taste than with more severe indicators of the new coronavirus such as shortness of breath, cough or fever, according to the study.
“If you had asked me why I should be depressed or anxious when I am positive COVID, I would say it is because my symptoms are severe and I have shortness of breath or I cannot breathe or I have symptoms such as cough or high fever,” said Ahmad Sedaghat, MD , PhD, associate professor and director of rhinology, allergy and surgery of the anterior skull base, at the Department of Otolaryngology-Head and Neck Surgery of UC College of Medicine.
“None of these symptoms that presaged morbidity or mortality was associated with how depressed or anxious these patients were,” said Sedaghat, also a UC Health doctor specializing in nose and sinus diseases.
“The only element of COVID-19 associated with depressed mood and anxiety was the severity of the patients’ loss of smell and taste. This is an unexpected and shocking result, “added Sedaghat.
Sedaghat conducted a prospective and cross-sectional telephone questionnaire study that examined the characteristics and symptoms of 114 patients who were diagnosed with COVID-19 for a six-week period at the Kantonsspital Aarau in Aarau, Switzerland.
The severity of loss of smell or taste, nasal obstruction, excessive mucus production, fever, cough and shortness of breath during COVID-19 were assessed. The study results are available online in The Laryngoscope.
The first author of the study is Marlene M. Speth, MD, and other co-authors include Thirza Singer-Cornelius, MD; Michael Oberle, PhD; Isabelle Gengler, MD; and Steffi Brockmeier, MD.
At the time of enrollment in the study, when participants presented COVID-19, 47.4 percent of participants reported at least several days of depressed mood per week while 21.1 percent reported depressed mood almost every day. In terms of severity, 44.7 percent of participants reported expressing mild anxiety while 10.5 percent reported severe anxiety.
“The unexpected discovery that the potentially least worrying symptoms of COVID-19 may cause the greatest degree of psychological distress could potentially tell us something about the disease,” said Sedaghat.
“We think our results suggest the possibility that psychological distress in the form of depressed mood or anxiety may reflect the penetration of SARS-CoV-2, the virus that causes COVID-19, into the central nervous system,” added Sedaghat.
Sedaghat says researchers have long thought that the olfactory tract could be the primary way that coronaviruses enter the central nervous system. Evidence emerged with SARS, or severe acute respiratory syndrome, a viral disease that first emerged in China in November 2002 and spread through international travel to 29 countries.
Studies conducted using mouse models of that virus have shown that the olfactory tract, or the pathway for communicating odors from the nose to the brain, was a gateway to the central nervous system and brain infection.
“These symptoms of psychological distress, such as depressed mood and anxiety, are symptoms of the central nervous system if they are associated only with how much your sense of smell has decreased,” said Sedaghat.
“This may indicate that the virus is infecting olfactory neurons, decreasing the sense of smell and therefore using the olfactory tract to enter the central nervous symptom,” added Sedaghat.
Rare but serious central nervous system symptoms of COVID-19 have been described as seizures or altered mental status, but depressed mood and anxiety may be the considerably more common but milder central nervous symptom of COVID-19, explains Sedaghat.
“There may be a greater penetration of the virus into the central nervous system than we think based on the prevalence of depressed mood and anxiety associated with the sense of smell and this really opens the door to future investigations to see how the virus could interact with the central nervous system, “Said Sedaghat.