Neurobehavior and Brain Connectivity in Post COVID-19 Patients

Auditory attention is measured with Digit Span Forward. Participants are asked to repeat numbers in the same order as read aloud by the examiner. Higher scores mean a better outcome.

Working memory is measured with Digit Span Backward. Participants are asked to repeat the numbers in the reverse order of that presented by the examiner. Higher scores mean a better outcome.

Language is measured with the Boston Naming Test. It consists of 60 line drawings of objects of graded difficulty, ranging from very common things to less familiar objects. The total score is the sum of correct answers. Higher scores mean a better outcome.

Verbal memory is measured with the Auditory Verbal Learning Test (AVLT). It is a word-learning test where five presentations of a 15-word list are given, each followed by an attempted recall. This is followed by a second 15-word interference list (list B), followed by recall of list A. Delayed recall and recognition are also tested. Higher scores mean a better outcome.

Visual memory is measured with the Rey-Osterrieth Complex Figure (ROCF) test. The participants are asked to copy complex geometric shapes and then reproduce them from memory. A delayed recall is also tested. Higher scores mean a better outcome.

Processing speed is measured with Coding subtest of WAIS. Participants are asked to use a key to put in the appropriate symbols for a list of numbers. Higher scores mean a better outcome.

Perceptual reasoning is measured with Matrix reasoning subtest of WAIS. Participants are asked to choose which of some possible options the missing picture is from matrix of abstract pictures. Higher scores mean a better outcome.

A composite score is made with the z-scores of phonemic (sum of the three letters) and semantic fluency, Trail Making Test B (time) and STROOP test (color-word interference total items in 120 seconds).

Social cognition is measured with the Reading the Mind in the Eyes Test. Participants are asked to choose the emotional state that best describes the eyes, choosing between one of four possible emotions in the 36 photographs of male and female eyes depicting emotional states. Higher scores mean a better outcome.

Anxiety is measured with the 7-item Generalized Anxiety Disorder Scale (GAD-7), a Likert-type scale with questions ranging from "not at all" (0 points) to "nearly every day" (3 points). The maximum score is 24. Higher scores mean a worse outcome.

Depression is measured with the Patient Health Questionnaire-9 (PHQ-9) which scores each of the 9 DSM-IV criteria as "not at all" (0 points) to "nearly every day" (3 points). Higher scores mean a worse outcome.

Post-Traumatic Stress Disorder is measured with The Post-Traumatic Stress Disorder Checklist (PCL-5), a 20-item questionnaire corresponding to the DSM-5 symptom criteria for PTSD, which scores each criterion as "not at all" (0 points) to "extremely" (4 points). The ratings of items are added together to calculate the total score (range=0-80). Higher scores mean a worse outcome.

Fatigue is measured with the Chalder Fatigue Scale, an 11-item questionnaire measuring the severity of physical and mental fatigue on two separate subscales. Seven items represent physical fatigue (items 1-7) and 4 represent mental fatigue (items 8-11). Each item " less than usual" (0) to " much more than usual" (3). The ratings of items are added together to calculate the total score (range=0-33). High scores represent high levels of fatigue.

Quality of life is measured with a 12-item World Health Organization Disability Assessment Schedule-II (WHODAS-II). Patients are asked to state the level of difficulty experienced, considering how they usually do the activity. The scale scores each item as "none" (1) to "cannot do" (5). The total score is calculated with an SPSS syntax, and the range varies from 0 to 100, with higher scores reflecting more significant disability.

White matter integrity: tractography measured by MRI

Grey and white matter volume measured by MRI

Resting state brain activity using fMRI

The plasma levels of IL-6 are measured with enzyme-linked immunosorbent assay (ELISA) Kit

The plasma levels of NGF are measured with ELISA Kit

The plasma levels of GFAp are measured with ELISA Kit

The plasma levels of malondialdehyde are measured with TBARS assay method

The plasma levels of Ferritin are measured with biochemical assay

The plasma levels of CRP are measured with high sensitivity c-reactive protein ELISA Kit

Smell function is evaluated with the University of Pennsylvania Smell Identification Test (UPSIT), which measures the individual's ability to detect odors at a suprathreshold level. The UPSIT comprises four booklets, each of which contains ten pages. An odorized "scratch & sniff" label is present on each booklet page. The subject scratches the label and then indicates which of the four response alternatives best matches the perceived smell. A score ranging from 6-18 means anosmia, 19-25 means severe microsmia, 26-30 in women and 26-29 in men means moderate microsmia, 31-34 in women and 30-33 in men means mild microsmia and a score of more than 34 in women and 33 in men means normosmia.

Retinal plexuses integrity is measured with Optical Coherence Tomography Angiography (OCTA)