Nonlinear EEG Analysis During Motor and Cognitive Tasks in Patients With Long COVID: A Dynamic Systems Approach.

Introduction. Nonlinear EEG provides information about dynamic properties of the brain. This study aimed to compare nonlinear EEG parameters estimated from patients with Long COVID in different cognitive and motor tasks. Materials and Methods. This 12-month prospective cohort study included 83 patients with Long COVID: 53 symptomatic and 30 asymptomatic. Brain electrical activity was evaluated by EEG in 4 situations: (1) at rest, (2) during the Trail Making Test Part A (TMT-A), (3) during the TMT Part B (TMT-B), and (4) during a coordination task: the Box and Blocks Test (BBT). Nonlinear EEG parameters were estimated in the time domain (activity and complexity). Assessments were made at 0 to 3, 3 to 6, and 6 to 12 months after inclusion. Results. There was a decrease in activity and complexity during the TMT-A and TMT-B, and an increase of these parameters during the BBT in both groups. There was an increase in activity at rest and during the TMT-A in the COVID-19 group at 0 to 3 months compared to the control, an increase in activity in the TMT-B in the COVID-19 group at 3 to 6 months compared to the control, and reduced activity and complexity at rest and during the TMT-A at 6 to 12 months compared to the control. Conclusion. The tasks followed a pattern of increased activity and complexity in cognitive tasks, which decreased during the coordination task. It was also observed that an increase in activity at rest and during cognitive tasks in the early stages, and reduced activity and complexity at rest and during cognitive tasks in the late phases of Long COVID.

Changes in Electrical Brain Activity and Cognitive Functions Following Mild to Moderate COVID-19: A one-Year Prospective Study After Acute Infection.

The coronavirus disease 2019 (COVID-19) can disrupt various brain functions. Over a one-year period, we aimed to assess brain activity and cognitive function in 53 COVID-19 patients and 30 individuals without COVID-19 (or asymptomatic). The Montreal Cognitive Assessment, Trail Making Test Parts A and B (TMT-A and B), and Digit Span Test were used to assess cognitive function. Cognitive variables and electroencephalography (EEG) data (activity, mobility, and complexity) were compared between the groups at rest and during cognitive demand (F3-F7, Fz-F3, Fz-F4, and F4-F8). There was a reduction in F3-F7 activity during the TMT-B in the COVID-19 group at 6-12 months compared to the controls (p = 0.01) at baseline (p = 0.03), a reduction in signal complexity at F3-F7 at rest in the COVID-19 group at baseline and 6-12 months compared to the controls (p < 0.001), and a reduction in Fz-F4 activity at rest from 6-12 months in the post-COVID group compared to baseline (p = 0.02) and 3-6 months (p = 0.04). At 6-12 months, there was a time increase in TMT-A in the COVID-19 group compared to that in the controls (p = 0.04). Some correlations were found between EEG data and cognitive test in both groups. In conclusion, there was a reduction in brain activity at rest in the Fz-F4 areas and during high cognitive demands in the F3-F7 areas. A reduction in signal complexity in F3-F7 at rest was found in the COVID-19 group at 6-12 months after acute infection. Furthermore, individuals with COVID-19 experience long-term changes in cognitive function.

Effect of transcranial direct current stimulation in addition to visuomotor training on choice reaction time and cognition function in amateur soccer players (FAST trial): A randomized control trial.

OBJECTIVES: This study aimed to evaluate the effect of anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) in addition to visuomotor training (VMT) on choice reaction time (CRT) and cognitive function in amateur soccer players. DESIGN: Single-center, randomized, placebo-controlled, double-blind, parallel-group study. SETTING: Neuroscience and Motor Control Laboratory. PARTICIPANTS: Thirty Brazilian male amateur soccer players, aged 18-30 years. MAIN OUTCOME MEASURES: Participants were allocated to the intervention or control groups. Both groups performed VMT, but the intervention group additionally underwent anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC; F3). The cathodal electrode was positioned in the right supraorbital region (Fp2). The tDCS was applied at 2 mA for 20 min for five consecutive sessions (24 h intervals). The VMT protocol was delivered during the application of tDCS and was composed of kicking a ball for 10 min (between the fifth and fifteenth minutes of the 20 min of tDCS application). The primary outcome was assessed based on changes in CRT during reaching (non-trained limb) and kicking (trained limb) tasks. Secondary outcomes were overall cognitive function measured by the Trail Making Test part A (TMT-A) and part B (TMT-B), and Digit Span Test forward (DSF) and backward (DSB) scores. All outcomes were evaluated before and after the intervention. RESULTS: In the primary outcomes, compared with the control group, the anodal tDCS combined with VMT group had greater reduction in CRT for the rectus femoris (p = 0.007) adjusted for age and baseline performance (F (1,26) = 22,23; p < 0,001) and for the triceps (p = 0.039) adjusted for training frequency (days/week) and baseline performance (F (1,26) = 5,70; p = 0,016). No differences were observed in the CRT of other muscles (anterior deltoid [p = 0.181], brachial biceps [p = 0.130], and vastus medialis [p = 0.074]). And, there were no differences between the groups in terms of cognitive function (TMT-A [p = 0.062]; TMT-B [p = 0.320]; DSF [p = 0.102]; DSB [p = 0.345]). CONCLUSION: Anodal tDCS over the left DLPFC in addition to visuomotor training of a functional task can be an efficient tool for athletes to decrease the CRT of the rectus femoris (trained limb) and triceps (non-trained limb); however, there were no differences between the groups in the others muscles (anterior deltoid, brachial biceps, and vastus medialis), and in terms of cognitive function.

Virtual Reality Immersion in Healthy Individuals: Ellipse Sway Area of an Electrical Shuttle Balance.

To assess indirectly the effects of virtual reality (VR) immersion on postural sway in thirteen healthy individuals. The ellipse sway area was recorded with an accelerometer coupled to an electrical shuttle balance under six conditions, varying Romberg and single leg stance (SLS) position with eyes open and eyes closed. The length of the ellipse traveled over 10 s was measured and Romberg and single leg stance (SLS) ratios were calculated. Ellipse sway area was reduced in all positions after VR intervention. Statistical differences were observed in the left SLS ratio 24 hr after comparison to the baseline. A single VR session could reduce ellipse sway area and decrease the visual dependency of posture control indicating increased ability to maintain stable body sway over the shuttle.

Impact of unilateral spatial neglect on chronic patient's post-stroke quality of life.

BACKGROUND: Unilateral spatial neglect (USN) is the prevalent feature in patients with right-sided stroke. It is diagnosed through the behavior inattention test (BIT) and has a negative impact on patients affecting both their functional capacity and quality of life. OBJECTIVE: Here, we aimed to evaluate the impact of USN on the quality of life of patients in the chronic phase of stroke. METHODS: This is a cross-sectional study with stroke patients with USN. After confirming the presence of stroke through neuroimaging examinations and of USN through the BIT, patients' quality of life was evaluated by using the EUROQOL scale. Spearman's correlation was used to validate the correlation between patients' USN and quality of life, with a p < .05 representing significant results. RESULTS: Eighteen individuals were included. When correlating the value of each domain of the EUROQOL scale with the results of the BIT, we observed a negative correlation between mobility (r = -0.97; p = .000), self-care (r = -0.82; p = .013), usual activities (r = -0.87; p = .005); pain or discomfort (r = -0.88; p = .004), anxiety or depression (r = -0.97; p = .000), and EUROQOL total score (r = -0.97, p = .000). CONCLUSION: After a correlation between the overall EUROQOL and BIT scores, we suggest that the higher the USN degree is in stroke patients, the worse their perceived quality of life tends to be.

Crossed Leg Sign Is Associated With Severity of Unilateral Spatial Neglect After Stroke.

BACKGROUND: The crossed leg sign in patients with right hemisphere stroke is thought to be associated with perceptual disorders, such as unilateral spatial neglect (USN). The aim of this study was to compare the crossed leg sign with the severity of USN during the acute phase of stroke. EXPERIMENTAL PROCEDURES: This was an observational and prospective clinical study of individuals with a diagnosis of right parietal stroke, as confirmed by neuroimaging. The occurrence of the crossed leg sign, the time at which this occurred after the stroke, and a clinical diagnosis of USN were measured and recorded. The patients' age, sex, and lesion severity, as determined by the National Institutes of Health Stroke Scale and Glasgow coma scale, were included in the analyses as confounding variables. The outcome of interest was the degree of USN, as measured by the cancellation and bisection tests. Binary logistic regression was used to analyze the effect of crossed leg syndrome on the severity of USN. In the adjusted multiple regression model, a p-value of <0.05 was considered statistically significant. RESULTS: Overall, 60 patients were included in this study. There were no associations between patient demographics and the presence of the crossed leg sign. There was, however, an association between the crossed leg sign and the absolute value of the deviation in the line bisection test (B = -0.234; p = 0.039). The crossed leg sign was not associated with other measures of USN. CONCLUSION: Based on the results of our study, we can conclude that a crossed leg sign in the acute phase of stroke is associated with USN severity, specifically the misinterpretation of the midline.