Today in JAMA Network Open, a survey of 14,767 people shows that 57% of those with post–COVID-19 condition—or long COVID—said they experienced symptoms of a cognitive (thinking) deficit daily at least 2 months following infection, as well as symptoms of depression.
Only 27% with prior SARS-CoV-2 infection who did not develop post–COVID-19 condition said they experienced cognitive symptoms as frequently.
Also today, researchers publishing in Emerging Infectious Diseases demonstrate that people who have had COVID-19 are at four times greater risk of developing chronic fatigue compared with these who did not have COVID.
Younger age, depression associated with cognitive symptoms
The first study was based on a web-based survey conducted from December 22, 2022, to May 5, 2023. Among other questions on symptoms, participants were asked to rate on a 5-point scale how often they experienced the following over the previous week: slowed thinking, trouble concentrating, having to work hard to pay attention to avoid making mistakes, trouble getting started, trouble remembering (such as taking medicine or buying something), difficulty multitasking, and trouble making decisions.
Participants were also asked to assess their mood and daily functioning, as well as to provide sociodemographic information.
The survey included 1,683 people (11.4% of all respondents) who met the definition of post–COVID-19 condition (new or persistent symptoms at least 8 weeks following infection). Of those, 955 (56.7%) reported at least one cognitive symptom daily, including trouble concentrating (38.1%) and trouble with decision-making (25.3%).
"Features associated with a greater number of daily symptoms included younger age and lower income," the authors said. The greatest number of cognitive symptoms were seen among those 18 to 24 years and 45 to 54 years. Those 65 years and older were least likely to report daily cognitive symptoms.
Features associated with a greater number of daily symptoms included younger age and lower income.
Daily cognitive symptoms were associated with moderate interference with everyday functioning (adjusted odds ratio [AOR] 1.27; 95% confidence interval [CI], 1.21 to 1.33) and between cognitive symptoms and lower odds of full-time employment (AOR, 0.92).
The number of cognitive symptoms reported at least daily was also associated with greater severity of depressive symptoms (adjusted coefficient, 1.27; 95% CI, 1.17 to 1.38).
The authors warned however, that the association between depression and long COVID was complex.
"Individuals with post–COVID-19 condition, particularly in the pandemic, may have initially been diagnosed with depression or anxiety, before post–COVID-19 condition as a syndrome was recognized," they wrote. "Our observation of the overlap between cognition and mood in post–COVID-19 condition does not in any way suggest any causal relationship."
COVID-19 infection linked to fatigue
In the second study, researchers from the US Centers for Disease Control and Prevention (CDC) and the University of Washington assessed the risk of fatigue and long-term (chronic) fatigue among those who did and did not have COVID.
The study was based on electronic health records of 4,589 patients with confirmed COVID-19 between February 2020 and February 2021 who were assessed for an average of 11.4 months. Outcomes were compared with 9,022 matched non–COVID-19 controls.
Among those with COVID, 15% required hospitalization. The incidence rate of fatigue among those with COVID was 10.2 per 100 person-years, and the rate of chronic fatigue was 1.8 per 100 person-years.
When compared to the controls, the hazard ratios were 1.68 (95% CI, 1.48 to 1.92) for fatigue and 4.32 (95% CI, 2.90 to 6.43) for chronic fatigue. Women were 39% more likely have an fatigue diagnosis than men were.
"We noted no strong evidence of a racial or ethnic difference in incidence of fatigue, except a slightly lower incidence among Black patients. Persons with more comorbidities experienced higher incidence rates than did persons without comorbidities," the authors wrote.
