Evidence of impaired processing speed and cognitive control in recovered COVID-19 patients: The role of cognitive slowing in long COVID memory impairment

Cognitive impairment is among the most reported symptoms in post-acute sequelae of SARS-CoV-2 infection. These impairments, often termed "brain fog" include difficulties in memory, attention, executive function, and processing speed, significantly impacting individuals' quality of life and daily functioning. This study investigates the hypothesis that survivors may exhibit impaired processing speed (PS) and cognitive control (CC), crucial components of cognitive functioning that potentially underlie learning and memory disturbances. An observational study was conducted with 61 participants (mean age: 35.7 ± 8.7 years, 53% female, 47% male), categorized into three groups: control (CTL), COVID symptomatic (COV-S), and hospitalized (COV-H). Participants were recruited through a sociodemographic and screening questionnaire and assessed using various cognitive and psychological evaluation tools, including the Five-Digit Test (FDT) and Rey Auditory Verbal Learning Test (RAVLT). Results indicate that declines in processing speed and cognitive control are related to the clinical condition of COVID-19, with greater severity observed in hospitalized individuals. The study provides robust evidence that COVID-19 affects processing speed and cognitive control, directly leading to slowed learning stages and impairments in the RAVLT encoding stage, due to increased interference during memory formation, affecting episodic-semantic memory tasks.