Improving Cognitive Health in COVID-19 Survivors

Change in cognitive function in the experimental group vs. controls, measured by score on the Digit Symbol Matching Task, a timed measure of attention and processing speed. Participants are asked to correctly match pairs of shapes and numbers. Scores exceeding the normative mean number correct (mean = 65.79) reflect better task performance and scores below the normative mean reflect poorer performance.

Change in scores on the NeuroQOL Cognitive Function scale in the experimental group vs. controls. The NeuroQOL Cognitive Function scale is a 28-item self-report measure of daily functioning. Higher scores, defined as those exceeding the population mean (mean (SD) = 50.09 (10.23)), reflect better self-reported daily cognitive abilities, while lower scores, defined as those falling below the population mean, reflect poorer self-reported daily cognitive abilities.

Change in scores on the Multiple Object Tracking task in the experimental group vs. controls This task measures sustained attention, cognitive control, and working memory, and requires participants to remember and track a set of target circles as they move around the screen, among a larger set of identical distractor circles. The outcome measure is the proportion of dots that a participant was able to track and identify successfully (on a scale of 0 to 1, with 0 being no dots and 1 being all of the dots). Higher proportion reflects better performance, while lower proportions reflect poorer task performance.

Change in scores on the Test My Brain (TMT) Digit Span Backwards task in the experimental group vs. controls. This task measures sustained attention and working memory. Participants are shown a series of numbers and asked to reproduce them in reverse order. Higher digit spans, defined as those exceeding the population mean (M = 5.98) reflect better performance, while lower digit spans reflect poorer task performance.

Change in scores on the Simple Reaction Time task in the experimental group vs. controls This task measures simple reaction time and psychomotor speed, and requires participants to press a key whenever a green square appears. Faster response times indicate better performance than slower response times.

Change in scores on the Choice Reaction Time task in the experimental group vs. controls This task measures processing speed and cognitive control, and requires participants to indicate the direction of an arrow that is a different color from the rest. Faster response times indicate better performance than slower response times.

This task measures sustained attention and set-shifting, and requires participants to switch between responses to letters and numbers. The outcome measure is proportion of correct switch trials, indicating that participants successfully switched from a letter response to a number response, or vice versa (on a scale of 0 to 1, with 0 being no correct switches and 1 being correct switches on all switch trials). Higher proportion correct for switch trials indicates better set-shifting performance, while lower proportion correct indicates worse set-shifting performance.

This task measures sustained attention and response inhibition, and requires participants to respond to target stimuli and ignore distractors. Performance is measured by d-prime, a measure of memory sensitivity and discrimination. D-prime is based on the calculation of hits (i.e., responding to a target when a target is present), misses (i.e., not responding when a target is present), false alarms (i.e., responding to a target when a distractor is present), and correct rejections (i.e., not responding when a distractor is present). D-prime scores range from 0 (chance) to 4.65 (based on hit rate of 0.99 and false alarm rate of 0.01). Greater d-prime scores reflect better performance than lower d-prime scores.

Change in scores on the Visual Paired Associates Task in the experimental group vs. controls. This task measures visual memory, and requires participants to learn and identify image pairs. The outcome measure is proportion of image pairs successfully recalled (on a scale of 0 to 1, with 0 being no image pairs and 1 being all of the image pairs). A higher proportion of correct image pairs reflects better performance than a lower proportion of correct image pairs.

Change in total score on the 36-item WHODAS in the experimental group vs. controls. The WHODAS 2.0 assesses the following domains of functioning: cognition, mobility, getting along, self-care, participation, and life activities. Scores range from 0 (no disability) to 100 (maximum disability), with higher scores reflecting a greater degree of overall functional disability.