Information Processing Speed Assessed with Letter Digit Substitution Test in Croatian Sample of Multiple Sclerosis Patients

Systematic review of cognitive reserve in multiple sclerosis: Accounting for physical disability, fatigue, depression, and anxiety

BACKGROUND

Cognitive reserve (CR) describes an individual's ability to adapt cognitive processes in response to brain atrophy, and has been reported to explain some of the discrepancy between brain atrophy and cognitive functioning outcomes in multiple sclerosis (MS). CR in MS is typically investigated by assessing an individual's pre- and/or post-diagnosis enrichment, which includes premorbid intellectual abilities, educational level, occupational attainment, and engagement in cognitively enriching leisure activities. Common MS symptoms (e.g., physical disability, fatigue, depression, anxiety) may impact an individual's ability to engage in various CR-enhancing activities post-diagnosis. It is unknown to what extent these MS symptoms have been taken into account in MS research on CR. As such, we identified whether studies assessed CR using measures of premorbid or continuous (including post-diagnosis) enrichment. For studies investigating continuous enrichment, we identified whether studies accounted for MS-impact, which MS symptoms were accounted for, and how, and whether studies acknowledged MS symptoms as potential CR-confounds.

METHODS

Three electronic databases (PsycINFO, PubMed, Scopus) were searched. Eligible studies investigated CR proxies (e.g., estimated premorbid intellectual abilities, vocabulary knowledge, educational level, occupational attainment, cognitively enriching leisure activities, or a combination thereof) in relation to cognitive, brain atrophy or connectivity, or daily functioning outcomes in adult participants with MS. We extracted data on methods and measures used, including any MS symptoms taken into account. Objectives were addressed using frequency analyses and narrative synthesis.

RESULTS

115 studies were included in this review. 47.8% of all studies investigated continuous enrichment. Approximately half of the studies investigating continuous enrichment accounted for potential MS-impact in their analyses, with only 31.0% clearly identifying that they treated MS symptoms as potential confounds for CR-enhancement. A narrative synthesis of studies which investigated CR with and without controlling statistically for MS-impact indicated that accounting for MS symptoms may impact findings concerning the protective nature of CR.

CONCLUSION

Fewer than half of the studies investigating CR proxies in MS involved continuous enrichment. Just over half of these studies accounted for potential MS-impact in their analyses. To achieve a more complete and accurate understanding of CR in MS, future research should investigate both pre-MS and continuous enrichment. In doing so, MS symptoms and their potential impact should be considered. Establishing greater consistency and rigour across CR research in MS will be crucial to produce an evidence base for the development of interventions aimed at improving quality of care and life for pwMS.

Symptom-Level Disability Status Assessed with an Electronic Unsupervised Patient-Reported Expanded Disability Status Scale (ePR-EDSS) in Multiple Sclerosis Patients-The Example of Croatia

The present study aimed to apply an electronic, unsupervised patient-reported Expanded Disability Status Scale (ePR-EDSS) to investigate disability severity in people with multiple sclerosis (pwMS) as a case study in Croatia in 2021, including demographic and comorbidity characteristics and multiple sclerosis (MS) disease-related factors. The cross-sectional study was conducted as an online survey from 4 October 2021 to 31 December 2021. Symptom-level disability status was assessed with ePR-EDSS for MS capturing MS-related disability across the spectrum of severity.The study enrolled 147 pwMS patients, of which 84% were women. The mean age ± standard deviation in the sample was 41.1 ± 11.3, and the mean disease duration was 8.5 ± 7.4 years, with a median EDSS score of 3.0 (range, 0−8). The distribution of the participants according to clinical forms of MS was as follows: 71% had relapsing-remitting MS, 13% had primary progressive MS, 4% had secondary progressive PMS, and 12% did not provide information on their MS type. Twenty-nine point two percent (29.2%) of the participants had comorbidities in addition to MS. EDSS scores indicate significant differences with regard to age (t = −3.51, p < 0.001), gender (χ2 = 8.04, p < 0.01), and immunomodulatory drug use (χ2 = 5.89, p < 0.05). An ePR-EDSS analysis of disability symptoms showed a significant difference in symptoms with regard to strength, sensation, coordination, vision, fatigue, mobility, and overall wellness among MS types. Participants with PPMS and SPMS were older on average, had higher EDSS, and had more pronounced symptoms of disability measured with ePR-EDSS compared to those with RRMS. Application of ePR-EDSS shows it to be a reliable eHealth tool for clinical assessment of pwMS disability status, and future studies should correlate it with standard self-report scales capturing MS symptoms such as fatigue, depression, anxiety, and stress.

Working Memory Phenotypes in Early Multiple Sclerosis: Appraisal of Phenotype Frequency, Progression and Test Sensitivity

Working memory (WM) impairments are common and debilitating symptoms of multiple sclerosis (MS), often emerging early in the disease. Predominantly, WM impairments are considered in a binary manner, with patients considered either impaired or not based on a single test. However, WM is comprised of different activated subcomponents depending upon the type of information (auditory, visual) and integration requirements. As such, unique WM impairment phenotypes occur. We aimed to determine the most frequent WM phenotypes in early MS, how they progress and which WM test(s) provide the best measure of WM impairment. A total of 88 participants (63 early relapsing–remitting MS: RRMS, 25 healthy controls) completed five WM tests (visual–spatial, auditory, episodic, executive) as well as the symbol digit modalities test as a measure of processing speed. RRMS patients were followed-up for two years. Factors affecting WM (age/gender/intelligence/mood) and MS factors (disease duration/disability) were also evaluated. Some 61.9% of RRMS patients were impaired on at least one WM subcomponent. The most subcomponents impaired were visual,–spatial and auditory WM. The most common WM phenotypes were; (1) visual–spatial sketchpad + episodic buffer + phonological loop + central executive, (2) visual–spatial sketchpad + central executive. The test of visual–spatial WM provided the best diagnostic accuracy for detecting WM impairment and progression. The SDMT did not achieve diagnostic accuracy greater than chance. Although this may be unsurprising, given that the SDMT is a measure of cognitive processing speed in MS, this does highlight the limitation of the SDMT as a general screening tool for cognitive impairment in early MS.

Psychometric Properties of the Pittsburgh Sleep Quality Index (PSQI) in Patients with Multiple Sclerosis: Factor Structure, Reliability, Correlates, and Discrimination

Sleep disturbances and poor sleep are a common complaint in the population with multiple sclerosis (MS) disease. The most commonly reported scale is the Pittsburgh Sleep Quality Index (PSQI), measuring seven components of sleep quality. Yet, till today, the PSQI instrument has not been validated in people with multiple sclerosis (pwMS). The objective of our study was to add precision in sleep quality assessment by investigating the psychometric properties of PSQI (factor structure, reliability, validity based on relations with other variables, cut-off scores) in pwMS. The cross-sectional study included data on a total of 87 patients with MS and 216 control subjects. Demographic information, education level, and MS-related variables were ascertained. Psychometric properties were examined by estimating the validity, including factor structure, metric invariance, and relations with other MS- and non-MS-related variables, reliability, and discrimination ability of the PSQI. The Croatian version of the PSQI had a two-factor structure which demonstrated loading and partial intercept invariance between pwMS and the control group. The global score and both subscales had high internal consistencies (McDonald's omega and Cronbach's alpha coefficients) in pwMS and showed expected relations with demographic and MS-related variables. PwMS differed significantly in the PSQI global score from the control groups, although receiver operating characteristics (ROC) curve analysis did not indicate a clear cut-off point. The PSQI is a reliable and valid scale and can be applied in clinical settings for assessing sleep quality in pwMS.