Researchers have been working hard to better understand Long COVID’s risk factors, causes, and symptoms in order to more effectively target treatments. Two new European studies have shed more light on Long COVID symptoms.*

What the researchers did

In one study, published in Open Forum Infectious Diseases, researchers at Norway’s University of Oslo aimed to learn more about the effects of severe COVID-19 on brain function.

• Cognitive function was assessed in 75 COVID-19 patients, 13 months after they had been hospitalized (in June 2020).
• Patients’ average age was roughly 56 years, and they were assessed for such cognitive abilities as:
  • Short-term memory, 
  • Learning,  
  • Attention,  and 
  • Executive function (working memory, nimbleness of thought, and self-control).

In a second study, published in Nature Medicine, U.K. researchers at the University of Birmingham analyzed a primary care database of outpatients with any of 115 Long COVID symptoms lasting longer than three  months. They also looked at risk factors for persistent symptoms.

• Over 486,000 adult COVID-19 survivors and nearly 2 million uninfected control participants were matched for comparison by possible influencing factors (e.g., smoking status and underlying conditions).
• 4.5% of COVID survivors and 4.7% of controls had received at least one COVID-19 vaccine dose before being diagnosed.

What they found

In the first study, 53% of participants showed cognitive impairment on at least one test, particularly in areas like short-term memory, learning, attention, and executive functioning.

The researchers found that severe COVID-19, in which supplemental oxygen was received, was linked to greater odds of:

• Impaired short-term memory, 
• Learning,  
• Attention, and 
• Visuo-spatial processing (knowing where objects are in space). 

Risk was slightly lower after adjusting for underlying conditions, but the significance of the results remained unchanged.

In the second study, the researchers found 62 symptoms significantly associated with Long COVID. Symptoms with the greatest propensity for Long COVID were (from greatest propensity to least):

• Loss of smell (anosmia)
• Hair loss
• Sneezing
• Difficulty ejaculating
• Diminished libido

Long COVID risk factors were:

• Being female
• Younger age
• Non-White race/ethnicity
• Low socioeconomic status 
• Being a smoker
• Being obese
• Having various underlying conditions

Underlying conditions most associated with Long COVID were (from greatest association to least):

• Chronic obstructive pulmonary disease
• An enlarged prostate
• Fibromyalgia
• Anxiety
• Erectile dysfunction
• Depression
• Migraines
• Multiple sclerosis
• Celiac disease
• A learning disability

Symptoms most commonly found were:

• Loss of smell
• Breathlessness
• Chest discomfort
• Fever
• Amnesia
• Apraxia 
• Bowel incontinence
• Erectile dysfunction
• Hallucinations 
• Swelling in arms or legs

What it means

Regarding the first study, the researchers say other causes may be responsible for the cognitive decline besides COVID-19, such as pre-existing conditions or psychological stress, and that their findings need validating in larger studies with longer follow-up periods.

Concerning the second study, senior author Shamil Haroon, MBChB, Ph.D. said that the team’s findings validate patients’ experiences, and indicate that the breadth of Long COVID symptoms can’t be fully explained by lifestyle risk factors, chronic health conditions, and other variables. 

“The symptoms we identified should help clinicians and clinical guideline developers to improve the assessment of patients with long-term effects from COVID-19,” he said, “and to subsequently consider how this symptom burden can be best managed.”

They would like to see further research on:

• Long COVID’s disease course,
• Persistent symptom clusters, and
• Disease outcomes.

They’d also like to see more research on Long COVID’s health and social impacts in order to better support patients and create targeted treatments.

*Van Beusekom, M. (2022, July 27). Persistent hair loss, brain fog highlighted in long-COVID studies. Center for Infectious Disease Research and Policy. https://www.cidrap.umn.edu/news-perspective/2022/07/persistent-brain-fog-hair-loss-highlighted-long-covid-studies