Cognitive dysfunction characteristics of multiple sclerosis with aging.

BACKGROUND: We aimed to investigate the characteristics of cognitive impairment in older people with multiple sclerosis (MS). METHODS: Cross-sectional study that included participants that were examined with a common and comprehensive neuropsychological protocol. The subjects were matched by sociodemographic variables and the following groups were generated for comparisons: young MS versus healthy controls (HC) (n = 246), old MS versus HC (n = 198), young MS vs old MS (n = 226), MS vs Alzheimer's disease (AD)(n = 70), and MS vs Parkinson's disease (PD) (n = 62). The ICCoDiMS criteria were used to define cognitive impairment in MS. RESULTS: Cognitive impairment was more frequent in young than old patients (70.8 % vs 52.2 %). Attention and speed processing is the most frequent cognitive domain impaired in MS (54.9 % of young MS vs 32.7 % of old MS). The frequency of impairment in attention/processing speed (54.9 % vs 32.7 %) and episodic memory (27.9 % vs 14.3) was higher in the young group than in the old group. There were no statistically significant differences in the distribution of impairment in executive function (46.0 % vs 35.3 %), visuospatial (17.9 % vs 9.5 %), and language (12.4 % vs 17.7 %). In those patients meeting the criteria for cognitive impairment, young MS patients showed lower performance in attention/processing speed tests. Conversely, old MS patients showed lower performance in episodic memory, verbal fluency, and planning. There were no differences in the correlations between SDMT and other neuropsychological tests in young and old patients, which suggests similar cognitive processes underlying SDMT performance in both groups. There were differences between old MS and prodromal AD, especially in episodic memory, while the cognitive profile of old MS was largely shared with PD. CONCLUSIONS: Our study found that the cognitive profile of MS is defined by a characteristic impairment in attention and processing speed, which is present during the lifespan. The impairment in processing speed is less prominent in old age, whereas the impairment of other cognitive functions becomes more relevant. These findings suggest potential differences in the pathophysiological processes associated with cognitive impairment between young and old ages that warrant further investigation.

Cognitive profile in multiple sclerosis and post-COVID condition: a comparative study using a unified taxonomy.

Post-COVID condition (PCC) and multiple sclerosis (MS) share some clinical and demographic features, including cognitive symptoms and fatigue. Some pathophysiological mechanisms well-known in MS, such as autoimmunity, neuroinflammation and myelin damage, have also been implicated in PCC. In this study, we aimed to compare the cognitive phenotypes of two large cohorts of patients with PCC and MS, and to evaluate the relationship between fatigue and cognitive performance. Cross-sectional study including 218 patients with PCC and 218 with MS matched by age, sex, and years of education. Patients were evaluated with a comprehensive neuropsychological protocol and were categorized according to the International Classification of Cognitive Disorders system. Fatigue and depression were also assessed. Cognitive profiles of PCC and MS largely overlapped, with a greater impairment in episodic memory in MS, but with small effect sizes. The most salient deficits in both disorders were in attention and processing speed. The severity of fatigue was greater in patients with PCC. Still, the correlations between fatigue severity and neuropsychological tests were more prominent in the case of MS. There were no differences in the severity of depression among groups. Our study found similar cognitive profiles in PCC and MS. Fatigue was more severe in PCC, but was more associated with cognitive performance in MS. Further comparative studies addressing the mechanisms related to cognitive dysfunction and fatigue may be of interest to advance the knowledge of these disorders and develop new therapies.

A data-driven approach to complement the A/T/(N) classification system using CSF biomarkers.

AIMS: The AT(N) classification system not only improved the biological characterization of Alzheimer's disease (AD) but also raised challenges for its clinical application. Unbiased, data-driven techniques such as clustering may help optimize it, rendering informative categories on biomarkers' values. METHODS: We compared the diagnostic and prognostic abilities of CSF biomarkers clustering results against their AT(N) classification. We studied clinical (patients from our center) and research (Alzheimer's Disease Neuroimaging Initiative) cohorts. The studied CSF biomarkers included Aß(1-42), Aß(1-42)/Aß(1-40) ratio, tTau, and pTau. RESULTS: The optimal solution yielded three clusters in both cohorts, significantly different in diagnosis, AT(N) classification, values distribution, and survival. We defined these three CSF groups as (i) non-defined or unrelated to AD, (ii) early stages and/or more delayed risk of conversion to dementia, and (iii) more severe cognitive impairment subjects with faster progression to dementia. CONCLUSION: We propose this data-driven three-group classification as a meaningful and straightforward approach to evaluating the risk of conversion to dementia, complementary to the AT(N) system classification.

Normative Data in Cross-Cultural Neuropsychological Instruments in Spaniards and Colombians Living in Spain.

BACKGROUND: Cross-Cultural Dementia Screening (CCD), Rowland Universal Dementia Assessment Scale (RUDAS), and European Cross-cultural Neuropsychological Test Battery (CNTB) are three novel neuropsychological instruments developed from a cross-cultural perspective to reduce the impact of culture in cognitive assessment and improve the assessment in diverse populations. OBJECTIVE: We aimed to collect and present normative data on these tests in a majority population sample (Spaniards living in Spain) and in a minority population sample (Colombians living in Spain). METHODS: CCD, RUDAS, and CNTB were administered to a group of 300 cognitively healthy participants (150 Spaniards and 150 Colombians). Linear regression modeling strategy was used to provide adjusted norms for demographic factors and to explore the influence of these factors on test performance. RESULTS: Most of the CCD and CNTB scores were predicted by age and years of education, with some tests only predicted by age or showing a ceiling effect. The comparison of normative data between the two samples confirmed the favorable cross-cultural properties of these instruments, with only some differences in processing speed and executive functioning scores. CONCLUSIONS: Our study finds a comparable influence of demographic factors in both populations on the performance of CCD, RUDAS, and CNTB, confirming their adequate cross-cultural properties. We provide normative data for these tests in Spaniards and Colombians living in Spain.

FDG-PET-based neural correlates of Addenbrooke's cognitive examination III scores in Alzheimer's disease and frontotemporal degeneration.

Introduction: The Addenbrooke's Cognitive Examination III (ACE-III) is a brief test useful for neuropsychological assessment. Several studies have validated the test for the diagnosis of Alzheimer's disease (AD) and frontotemporal dementia (FTD). In this study, we aimed to examine the metabolic correlates associated with the performance of ACE-III in AD and behavioral variant FTD. Methods: We enrolled 300 participants in a cross-sectional study, including 180 patients with AD, 60 with behavioral FTD (bvFTD), and 60 controls. An 18F-Fluorodeoxyglucose positron emission tomography study was performed in all cases. Correlation between the ACE-III and its domains (attention, memory, fluency, language, and visuospatial) with the brain metabolism was estimated. Results: The ACE-III showed distinct neural correlates in bvFTD and AD, effectively capturing the most relevant regions involved in these disorders. Neural correlates differed for each domain, especially in the case of bvFTD. Lower ACE-III scores were associated with more advanced stages in both disorders. The ACE-III exhibited high discrimination between bvFTD vs. HC, and between AD vs. HC. Additionally, it was sensitive to detect hypometabolism in brain regions associated with bvFTD and AD. Conclusion: Our study contributes to the knowledge of the brain regions associated with ACE-III, thereby facilitating its interpretation, and highlighting its suitability for screening and monitoring. This study provides further validation of ACE-III in the context of AD and FTD.

Abnormal functional connectivity in radiologically isolated syndrome: A resting-state fMRI study.

BACKGROUND: Radiologically isolated syndrome (RIS) patients might have psychiatric and cognitive deficits, which suggests an involvement of major resting-state functional networks. Notwithstanding, very little is known about the neural networks involved in RIS. OBJECTIVE: To examine functional connectivity differences between RIS and healthy controls using resting-state functional magnetic resonance imaging (fMRI). METHODS: Resting-state fMRI data in 25 RIS patients and 28 healthy controls were analyzed using an independent component analysis; in addition, seed-based correlation analysis was used to obtain more information about specific differences in the functional connectivity of resting-state networks. Participants also underwent neuropsychological testing. RESULTS: RIS patients did not differ from the healthy controls regarding age, sex, and years of education. However, in memory (verbal and visuospatial) and executive functions, RIS patients' cognitive performance was significantly worse than the healthy controls. In addition, fluid intelligence was also affected. Twelve out of 25 (48%) RIS patients failed at least one cognitive test, and six (24.0%) had cognitive impairment. Compared to healthy controls, RIS patients showed higher functional connectivity between the default mode network and the right middle and superior frontal gyri and between the central executive network and the right thalamus (pFDR < 0.05; corrected). In addition, the seed-based correlation analysis revealed that RIS patients presented higher functional connectivity between the posterior cingulate cortex, an important hub in neural networks, and the right precuneus. CONCLUSION: RIS patients had abnormal brain connectivity in major resting-state neural networks and worse performance in neurocognitive tests. This entity should be considered not an "incidental finding" but an exclusively non-motor (neurocognitive) variant of multiple sclerosis.

Medications Modulating the Acid Sphingomyelinase/Ceramide System and 28-Day Mortality among Patients with SARS-CoV-2: An Observational Study.

Prior evidence indicates the potential central role of the acid sphingomyelinase (ASM)/ceramide system in the infection of cells with SARS-CoV-2. We conducted a multicenter retrospective observational study including 72,105 adult patients with laboratory-confirmed SARS-CoV-2 infection who were admitted to 36 AP-HP (Assistance Publique-Hôpitaux de Paris) hospitals from 2 May 2020 to 31 August 2022. We examined the association between the ongoing use of medications functionally inhibiting acid sphingomyelinase (FIASMA), which reduces the infection of cells with SARS-CoV-2 in vitro, upon hospital admission with 28-day all-cause mortality in a 1:1 ratio matched analytic sample based on clinical characteristics, disease severity and other medications (N = 9714). The univariate Cox regression model of the matched analytic sample showed that FIASMA medication use at admission was associated with significantly lower risks of 28-day mortality (HR = 0.80; 95% CI = 0.72-0.88; p < 0.001). In this multicenter observational study, the use of FIASMA medications was significantly and substantially associated with reduced 28-day mortality among adult patients hospitalized with COVID-19. These findings support the continuation of these medications during the treatment of SARS-CoV-2 infections. Randomized clinical trials (RCTs) are needed to confirm these results, starting with the molecules with the greatest effect size in the study, e.g., fluoxetine, escitalopram, and amlodipine.

Comorbidity patterns and mortality among hospitalized patients with psychiatric disorders and COVID-19

Objectives: To examine the association between psychiatric and non-psychiatric comorbidity and 28-day mortality among patients with psychiatric disorders and COVID-19. Methods: Multicenter observational retrospective cohort study of adult patients with psychiatric disorders hospitalized with laboratory-confirmed COVID-19 at 36 Greater Paris university hospitals (January 2020-May 2021) (n=3,768). First, we searched for different subgroups of patients according to their psychiatric and non-psychiatric comorbidities through cluster analysis. Next, we compared 28-day all-cause mortality rates across the identified clusters, while taking into account sex, age, and the number of medical conditions. Results: We found five clusters of patients with distinct psychiatric and non-psychiatric comorbidity patterns. Twenty-eight-day mortality in the cluster of patients with mood disorders was significantly lower than in other clusters. There were no significant differences in mortality across other clusters. Conclusion: All psychiatric and non-psychiatric conditions may be associated with increased mortality in patients with psychiatric disorders and COVID-19. The lower risk of death among patients with mood disorders might be in line with the potential beneficial effect of certain antidepressants in COVID-19, but requires further research. These findings may help identify at-risk patients with psychiatric disorders who should benefit from vaccine booster prioritization and other prevention measures.

Comorbidity Patterns and Mortality Among Hospitalized Patients with Psychiatric Disorders and COVID-19.

OBJECTIVE: To examine the association between psychiatric and non-psychiatric comorbidity and 28-day mortality among patients with psychiatric disorders and COVID-19. METHODS: We performed a multicenter observational retrospective cohort study of adult patients with psychiatric disorders hospitalized with laboratory-confirmed COVID-19 at 36 Greater Paris University hospitals (January 2020-May 2021) (N=3,768). First, we searched for different subgroups of patients according to their psychiatric and non-psychiatric comorbidities through cluster analysis. Next, we compared 28-day all-cause mortality rates across the identified clusters, while taking into account sex, age, and the number of medical conditions. RESULTS: We found 5 clusters of patients with distinct psychiatric and non-psychiatric comorbidity patterns. Twenty-eight-day mortality in the cluster of patients with mood disorders was significantly lower than in other clusters. There were no significant differences in mortality across other clusters. CONCLUSIONS: All psychiatric and non-psychiatric conditions may be associated with increased mortality in patients with psychiatric disorders and COVID-19. The lower risk of death among patients with mood disorders might be in line with the potential beneficial effect of certain antidepressants in COVID-19, but requires further research. These findings help identify at-risk patients with psychiatric disorders who should benefit from vaccine booster prioritization and other prevention measures.

Validation of the European Cross-Cultural Neuropsychological Test Battery (CNTB) for the assessment of mild cognitive impairment due to Alzheimer's disease and Parkinson's disease.

Background: The Cross-Cultural Neuropsychological Test Battery (CNTB) is a novel test battery specifically designed to reduce the impact of multiculturality in cognitive assessment. Objective: We aimed to validate the CNTB in Spaniards in patients with Alzheimer's disease (AD), including patients at mild cognitive impairment (MCI) and mild dementia stages, and Parkinson's disease with MCI (PD-MCI). Methods: Thirty patients with AD-MCI, 30 with AD-dementia (AD-D), and 30 with PD-MCI were recruited. Each clinical group was compared against a healthy control group (HC) with no differences in sex, age, or years of education. Intergroup comparisons, ROC analysis, and cut-off scores were calculated. Results: AD-MCI scored lower than HC in those subtests associated with episodic memory and verbal fluency. AD-D also showed lower scores in executive functions and visuospatial tests. Effect sizes for all the subtests were large. PD-MCI showed lower performance than HC in memory and executive functions, particularly on error scores, with large effect sizes. Comparing AD-MCI and PD-MCI, AD-MCI had lower memory scores, while PD-MCI showed the worst performance in executive functions. CNTB showed appropriate convergent validity with standardized neuropsychological tests measuring the same cognitive domains. We obtained similar cut-off scores to previous studies performed in other populations. Conclusions: The CNTB showed appropriate diagnostic properties in AD and PD, including those stages with mild cognitive impairment. This supports the utility of the CNTB for the early detection of cognitive impairment in AD and PD.

Transcranial direct current stimulation for post-COVID fatigue: a randomized, double-blind, controlled pilot study.

Fatigue is one of the most frequent and disabling symptoms of the post-COVID syndrome. In this study, we aimed to assess the effects of transcranial direct current stimulation on fatigue severity in a group of patients with post-COVID syndrome and chronic fatigue. We conducted a double-blind, parallel-group, sham-controlled study to evaluate the short-term effects of anodal transcranial direct current stimulation (2 mA, 20 min/day) on the left dorsolateral prefrontal cortex. The modified fatigue impact scale score was used as the primary endpoint. Secondary endpoints included cognition (Stroop test), depressive symptoms (Beck depression inventory) and quality of life (EuroQol-5D). Patients received eight sessions of transcranial direct current stimulation and were evaluated at baseline, immediately after the last session, and one month later. Forty-seven patients were enrolled (23 in the active treatment group and 24 in the sham treatment group); the mean age was 45.66 ± 9.49 years, and 37 (78.72%) were women. The mean progression time since the acute infection was 20.68 ± 6.34 months. Active transcranial direct current stimulation was associated with a statistically significant improvement in physical fatigue at the end of treatment and 1 month as compared with sham stimulation. No significant effect was detected for cognitive fatigue. In terms of secondary outcomes, active transcranial direct current stimulation was associated with an improvement in depressive symptoms at the end of treatment. The treatment had no effects on the quality of life. All the adverse events reported were mild and transient, with no differences between the active stimulation and sham stimulation groups. In conclusion, our results suggest that transcranial direct current stimulation on the dorsolateral prefrontal cortex may improve physical fatigue. Further studies are needed to confirm these findings and optimize stimulation protocols.

Multi-Disease Validation of the RUDAS for Cognitive Screening in Alzheimer's Disease, Parkinson's Disease, and Multiple Sclerosis.

BACKGROUND: The Rowland Universal Dementia Assessment Scale (RUDAS) is a cognitive test with favorable diagnostic properties for detecting dementia and a low influence of education and cultural biases. OBJECTIVE: We aimed to validate the RUDAS in people with Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). METHODS: We enrolled one hundred and fifty participants (60 with AD, 30 with PD, 60 with MS, and 120 healthy controls (HC)). All clinical groups completed a comprehensive neuropsychological battery, RUDAS, and standard cognitive tests of each disorder: MMSE, SCOPA-COG, and Symbol Digit Modalities Test. Intergroup comparisons between clinical groups and HC and ROC curves were estimated. Random Forest algorithms were trained and validated to detect cognitive impairment using RUDAS and rank the most relevant scores. RESULTS: The RUDAS scores were lower in patients with AD, and patients with PD and MS showed cognitive impairment compared to healthy controls. Effect sizes were generally large. The total score was the most discriminative, followed by the memory score. Correlations with standardized neuropsychological tests were moderate to high. Random Forest algorithms obtained accuracies over 80-90% using the RUDAS for diagnosing AD and cognitive impairment associated with PD and MS. CONCLUSION: Our results suggest the RUDAS is a valid test candidate for multi-disease cognitive screening tool in AD, PD, and MS.

Coronary microvascular dysfunction is associated with impaired cognitive function: the Cerebral-Coronary Connection study (C3 study).

BACKGROUND: It remains unknown whether the presence of coronary microcirculatory dysfunction (CMD) correlates with its equivalent condition in the brain, cerebral small vessel disease (CSVD). The cerebral-coronary connection (C3), a prospective blinded study, investigated the prevalence of CMD in patients with coronary artery disease (CAD) and its association with CSVD and cognitive function. METHODS AND RESULTS: Patients with documented CAD fulfilling inclusion criteria underwent physiological assessment of epicardial vessels and the microcirculation using intracoronary pressure and Doppler. Coronary microcirculation-related indices included coronary flow reserve (CFR) and hyperaemic microvascular resistance. Brain magnetic resonance imaging, transcranial Doppler (TCD), and neurocognitive examination were performed. Overall, 67 patients were included in the study (mean age 66 years, 73% female). Patients with abnormal CFR (<2.0) (55.2%) showed higher burden of white-matter hyperintensities: 43.2 vs. 20.0% (P = 0.044). After statistical adjustment, low CFR was associated with lower grey matter volume (P = 0.024) and with parameters of white-matter microstructural damage in diffusion-tensor imaging (lower fractional anisotropy and higher mean diffusivity, P = 0.029 and P = 0.032, respectively). Low CFR was associated with higher resistive (P = 0.027) and pulsatility (P = 0.043) values on TCD, and worse neurocognitive test scores (lower mini mental state examination, P = 0.025, and slower Trail Making Test A, P = 0.034). CONCLUSIONS: Coronary microcirculatory dysfunction is frequent in patients with CAD and correlates with CSVD, abnormal cerebral flow haemodynamics, and significant cognitive impairment. These findings support the hypothesis that microvascular dysfunction in the heart and the brain are part of a single pathological process affecting microcirculation in patients with CAD. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT04131075.

Neuropsychological, Metabolic, and Connectivity Underpinnings of Semantic Interference Deficits Using the LASSI-L.

BACKGROUND: LASSI-L is a novel neuropsychological test specifically designed for the early diagnosis of Alzheimer's disease (AD) based on semantic interference. OBJECTIVE: To examine the cognitive and neural underpinnings of the failure to recover from proactive semantic and retroactive semantic interference. METHODS: One hundred and fifty-five patients consulting for memory loss were included. Patients underwent neuropsychological assessment, including the LASSI-L, and FDG-PET imaging. They were categorized as subjective memory complaints (SMC) (n=32), pre-mild cognitive impairment (MCI) due to AD (Pre-MCI) (n=39), MCI due to AD (MCI-AD) (n=71), and MCI without evidence of neurodegeneration (MCI-NN) (n=13). Voxel-based brain mapping and metabolic network connectivity analyses were conducted. RESULTS: A significant group effect was found for all the LASSI-L scores. LASSI-L scores measuring failure to recover from proactive semantic interference and retroactive semantic interference were predicted by other neuropsychological tests with a precision of 64.1 and 44.8%. The LASSI-L scores were associated with brain metabolism in the bilateral precuneus, superior, middle and inferior temporal gyri, fusiform, angular, superior and inferior parietal lobule, superior, middle and inferior occipital gyri, lingual gyrus, and posterior cingulate. Connectivity analysis revealed a decrease of node degree and centrality in posterior cingulate in patients showing frPSI. CONCLUSION: Episodic memory dysfunction and the involvement of the medial temporal lobe, precuneus and posterior cingulate constitute the basis of the failure to recover from proactive semantic interference and retroactive semantic interference. These findings support the role of the LASSI-L in the detection, monitoring and outcome prediction during the early stages of AD.

Fatigue and Cognitive Dysfunction Are Associated with Occupational Status in Post-COVID Syndrome.

Post-COVID syndrome (PCS) is a medical condition characterized by the persistence of a wide range of symptoms after acute infection by SARS-CoV-2. The work capacity consequences of this disorder have scarcely been studied. We aimed to analyze the factors associated with occupational status in patients with PCS. This cross-sectional study involved 77 patients with PCS on active work before SARS-CoV-2 infection. Patients were evaluated 20.71 ± 6.50 months after clinical onset. We conducted a survey on occupational activity and cognitive and clinical symptoms. The association between occupational activity and fatigue, depression, anxiety, sleep quality, and cognitive testing was analyzed. Thirty-eight (49.4%) patients were working, and thirty-nine (50.6%) patients were not. Of those not working at the moment of the assessment, 36 (92.3%) patients were on sick leave. In 63 patients (81.8% of the sample), sick leave was needed at some point due to PCS. The mean duration of sick leave was 12.07 ± 8.07 months. According to the patient's perspective, the most disabling symptoms were cognitive complaints (46.8%) and fatigue (31.2%). Not working at the moment of the assessment was associated with higher levels of fatigue and lower cognitive performance in the Stroop test. No association was found between occupational status with depression and anxiety questionnaires. Our study found an influence of PCS on work capacity. Fatigue and cognitive issues were the most frequent symptoms associated with loss of work capacity.

Neural basis of visuospatial tests in behavioral variant frontotemporal dementia.

Background: Recent models of visuospatial functioning suggest the existence of three main circuits emerging from the dorsal ("where") route: parieto-prefrontal pathway, parieto-premotor, and parieto-medial temporal. Neural underpinnings of visuospatial task performance and the sparing of visuospatial functioning in bvFTD are unclear. We hypothesized different neural and cognitive mechanisms in visuospatial tasks performance in bvFTD and AD. Methods: Two hundred and sixteen participants were enrolled for this study: 72 patients with bvFTD dementia and 144 patients with AD. Visual Object and Space Perception Battery Position Discrimination and Number Location (VOSP-PD and VOSP-NL) and Rey-Osterrieth Complex Figure (ROCF) were administered to examine visuospatial functioning, together with a comprehensive neuropsychological battery. FDG-PET was acquired to evaluate brain metabolism. Voxel-based brain mapping analyses were conducted to evaluate the brain regions associated with visuospatial function in bvFTD and AD. Results: Patients with AD performed worst in visuospatial tasks in mild dementia, but not at prodromal stage. Attention and executive functioning tests showed higher correlations in bvFTD than AD with ROCF, but not VOSP subtests. Visuospatial performance in patients with bvFTD was associated with bilateral frontal regions, including the superior and medial frontal gyri, supplementary motor area, insula and middle cingulate gyrus. Conclusion: These findings support the role of prefrontal and premotor regions in visuospatial processing through the connection with the posterior parietal cortex and other posterior cortical regions. Visuospatial deficits should be interpreted with caution in patients with bvFTD, and should not be regarded as hallmarks of posterior cortical dysfunction.

Validation of a brief cross-cultural cognitive screening test in Multiple Sclerosis.

BACKGROUND: Several batteries have been developed for the cognitive assessment of people with multiple sclerosis (MS). However, all these tests have some limitations in general clinical practice and from a cross-cultural perspective. In this study, we aimed to validate a novel cognitive screening test, the Cross-Cultural Dementia screening test (CCD), in pwMS. METHODS: Seventy-five participants with relapsing-remitting MS and 75 healthy controls were enrolled and completed a comprehensive neuropsychological battery and the CCD. Intergroup comparisons, effect sizes, and correlations with previously validated tests were calculated for a majority and a pilot study of a minority sample. ROC curves were estimated, and random forest classification models were developed. RESULTS: There were statistically significant differences between cognitively impaired MS (MS-CI) group and healthy controls, and between MS-CI and non-cognitively impaired MS group in all subtests of CCD with medium to large effect sizes. Correlations with standardized neuropsychological tests were moderate to high, supporting concurrent validity. These results were replicated in the minority sample. The random forest models showed a very accurate classification using the CCD. This test showed good psychometric properties compared with SDMT. CONCLUSIONS: Our study validates the CCD for cognitive impairment screening in MS, showing advantages over other routinely used cognitive tests.

Neuropsychological Predictors of Fatigue in Post-COVID Syndrome.

Fatigue is one of the most disabling symptoms in several neurological disorders and has an important cognitive component. However, the relationship between self-reported cognitive fatigue and objective cognitive assessment results remains elusive. Patients with post-COVID syndrome often report fatigue and cognitive issues several months after the acute infection. We aimed to develop predictive models of fatigue using neuropsychological assessments to evaluate the relationship between cognitive fatigue and objective neuropsychological assessment results. We conducted a cross-sectional study of 113 patients with post-COVID syndrome, assessing them with the Modified Fatigue Impact Scale (MFIS) and a comprehensive neuropsychological battery including standardized and computerized cognitive tests. Several machine learning algorithms were developed to predict MFIS scores (total score and cognitive fatigue score) based on neuropsychological test scores. MFIS showed moderate correlations only with the Stroop Color-Word Interference Test. Classification models obtained modest F1-scores for classification between fatigue and non-fatigued or between 3 or 4 degrees of fatigue severity. Regression models to estimate the MFIS score did not achieve adequate R2 metrics. Our study did not find reliable neuropsychological predictors of cognitive fatigue in the post-COVID syndrome. This has important implications for the interpretation of fatigue and cognitive assessment. Specifically, MFIS cognitive domain could not properly capture actual cognitive fatigue. In addition, our findings suggest different pathophysiological mechanisms of fatigue and cognitive dysfunction in post-COVID syndrome.

Validation of two new scales for the assessment of fatigue in Multiple Sclerosis: F-2-MS and FACIT-F.

BACKGROUND: Fatigue is one of the most common symptoms in neurology, especially in MS patients with a prevalence of 65%. It is described as the most disabling symptom by 40% of MS patients. This study aimed to validate the Functional Assessment of Chronic Illness Therapy fatigue version (FACIT-F) and the F-2-MS scale, a new tool to distinguish between fatigue and fatigability. METHODS: One hundred and fifteen patients with relapsing-remitting MS were enrolled. All patients completed a comprehensive neuropsychological battery, previously validated in MS. Fatigue was evaluated using the Fatigue Severity Scale (FSS), the Modified version of the Fatigue Impact Scale (MFIS), the Functional Assessment of Chronic Illness Therapy measure system (fatigue version) (FCIT-F), and a new tool for the assessment of fatigue and fatigability: the F-2-MS scale. Internal consistency was estimated with Cronbach's Alpha. For intergroup comparisons, Student's t-test and Pearson's chi-squared test were used. Pearson's correlation test was calculated for quantitative variables. Cohen's d was calculated to evaluate the effect size. Binary logistic regression was performed, considering the presence of fatigue as a criterion variable, and the FACIT-F and F-2-MS scores were added as predictor variables. ROC curves were also estimated. We conducted a confirmatory factor analysis for the F-2-MS scale, considering two latent factors. RESULTS: FACIT-F and F-2-MS showed high internal consistency. Both scales were highly correlated with MFIS and FSS, and showed a low correlation with Symbol Digit Modalities Test. There were significant differences between fatigued and non-fatigued patients on FACIT-F and F-2-MS scores with large effect sizes. Both scales showed AUC > 0.90 and achieved a correct classification >87%. Confirmatory factor analysis showed moderate evidence of two dimensions on the F-2-MS scale. CONCLUSIONS: The FACIT-F and F-2-MS scales showed appropriated psychometric properties to be used as fatigue measures in clinical and research settings, allowing a correct distinction between patients with and without fatigue, and contributing to the understanding of the complexities of fatigue in MS.