Working memory profiles of patients with multiple sclerosis: Where does the impairment lie?

Executive functions in relapsing-remitting multiple sclerosis

Some studies suggest that patients with relapsing-remitting multiple sclerosis have problems in the functioning of working memory, and more specifically in executive functions, but the available results are still inconsistent. The aim of the present study was to examine executive functioning in multiple sclerosis using classical and representative tasks for divided attention, updating, attentional shifting, and inhibition. The sample was composed of 48 participants aged between 18 and 59 years (24 persons living with multiple sclerosis and 24 healthy participants matched in age and education level). The executive functions of divided attention, updating, attentional shifting, and inhibition were analyzed through the Dual-Task Paradigm, the N-Back task, the Trail Making Test (TMT), and the Stroop test, respectively. The analyses of the data showed that the functioning of working memory was impaired in multiple sclerosis in the executive functions of divided attention and updating when the group of persons living with MS and the control group were compared. In addition, the performance in the four executive functions analyzed did not show the same profile across the persons living with MS in the sample, as no deficit in attentional shifting or inhibition was observed. It can be concluded that the presence of deficits was observed only in the executive functions of divided attention and updating under the condition of greater cognitive demand. The clinical implications of these results are underlined due to their impact on daily life.

Cognitive impairment in multiple sclerosis: "classic" knowledge and recent acquisitions

Multiple sclerosis (MS) is a central nervous system (CNS) disease characterized by inflammation, axonal demyelination, and neurodegeneration, which can have a strong impact on all aspects of the life of the patient. Multiple sclerosis causes motor, sensory, cerebellar, and autonomic dysfunctions, as well as cognitive and psychoemotional impairment. The most frequently compromised cognitive domains are complex attention/information processing, memory, executive and visuospatial functions. Recently, alterations have also been evidenced in complex cognitive functions, such as social cognition, moral judgment, and decision-making. Cognitive impairment is characterized by high variability and can affect work skills, social interactions, coping strategies and more generally the quality of life of patients and their families. With the use of sensitive and easy-to-administer test batteries, an increasingly accurate and early diagnosis is feasible: this allows to determine the effectiveness of possible preventive measures, to predict the future progression of the disease and to improve the quality of life of patients. There is currently limited evidence regarding the efficacy, on cognitive impairment, of disease-modifying therapies. The most promising approach, which has received strong empirical support, is cognitive rehabilitation.

Are sex differences in self-estimated intelligence an elusive phenomenon? Exploring the role of working memory, creativity, and other psychological correlates in young and older adults

BACKGROUND

Although there is research examining the demographic predictors of self-estimated intelligence (SEI) in young adults, so far SEI in old age is little investigated. This study aims to examine the influence of additional variables such as self-estimated emotional intelligence (SEEQ), physical attractiveness, health, general optimism, religiousness, and working memory (WM) on SEI both in young and older adults.

METHODS

A total of 159 young (90 women, M_age  = 28.77, SD = 8.83) and 152 older adults (93 women, M_age  = 71.92, SD = 6.84) completed a measure of SEI as well as questions regarding the abovementioned variables. Given that WM is considered a very strong predictor of intelligence, neuropsychological assessment included the measurement of WM and phonologically cued semantic retrieval-verbal storage and processing in WM, as assessed by the Digit Span Forward and Verbal Fluency Task. The visual storage in WM was assessed with a variation of the Visual Patterns Test, and the visual storage and processing in WM with the Corsi blocks task (backward). Positive and Negative Affect Schedule (PANAS-X) was also administered as a possible influence on cognitive performance and SEI.

RESULTS

Young males rated their intelligence quotient (IQ) and emotional quotient (EQ) higher than young females. This was not confirmed for older adults, for which surprisingly the reversed pattern was found. Older women reported higher IQ and EQ than older men. Correlations showed for all participants that the higher they rated their IQ, the higher their ratings of EQ, physical attractiveness, health, and religiousness. No significant correlations between objective tests regarding WM and SEI were found, supporting SEI overestimations. Age, sex, physical attractiveness, and SEEQ were significant predictors of SEI.

DISCUSSION

For the first time, a reverse sex difference across age groups in SEI is found. Implications for individuals and healthcare professionals involved in assessment are suggested.

Working memory dysfunction differs between secondary progressive and relapsing multiple sclerosis: Effects of clinical phenotype, age, disease duration, and disability

BACKGROUND

Cognitive dysfunction is relatively common in patients with multiple sclerosis (MS). Although it occurs in all stages and all phenotypes of MS, it is more prevalent in secondary progressive MS (SPMS) compared to relapsing MS (RMS). It is unclear whether the higher frequency of cognitive impairment in SPMS is linked to the progressive phenotype or other clinical factors. In this study, we compared working memory in patients with RMS, SPMS, and healthy subjects. We also investigated the effects of age, disease duration, and disability on working memory performance.

METHODS

This case-control study enrolled 134 MS patients, 69 patients were diagnosed with RMS and 65 patients with SPMS, and 77 healthy control subjects. We designed two working memory tasks with different sets of stimuli (face vs. checkerboard) and different instructions (same or different vs. which one is the same).

RESULTS

Accuracy was significantly more impaired in SPMS patients than in RMS patients and both groups were worse than healthy subjects. This finding was similar between both tasks. Age and overall cognitive functions (measured with MoCA) also affected accuracy, but disease duration and disability only affected accuracy in working memory task with checkerboard stimuli.

CONCLUSION

MS patients are impaired in keeping the information in the visual working memory for a few seconds. Progressive phenotype significantly affected working memory accuracy, and this effect did not explain out with other demographic or clinical factors. Future studies are needed to reveal underlying mechanisms of working memory dysfunction in SPMS and working memory dysfunction as a biomarker of disease progression.

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.

Working Memory Deficits in Multiple Sclerosis: An Overview of the Findings

Although working memory (WM) and information processing speed (IPS) impairments in multiple sclerosis (MS) have been widely investigated, several questions, regarding the nature of these impairments and their relationship, remain unclear. The aim of this short communication article is to present an overview of our recent research findings regarding (a) the characteristics of WM impairment in MS patients and, more precisely, the degree of impairment observed in each WM's component, i.e., phonological loop, visuospatial sketchpad, central executive, and episodic buffer and (b) the relationship between IPS and each of the four WM components, in an attempt to expand the existing rather narrow understanding of the interconnection between reduced IPS and WM impairment. Two studies of our research team are presented here and their findings are briefly discussed, highlighting the importance of further research on a specific component, namely the episodic buffer component among MS patients.

Motor Imagery of Walking in People Living with and without Multiple Sclerosis: A Cross-Sectional Comparison of Mental Chronometry

Motor imagery represents the ability to simulate anticipated movements mentally prior to their actual execution and has been proposed as a tool to assess both individuals’ perception of task difficulty as well as their perception of their own abilities. People with multiple sclerosis (pwMS) often present with motor and cognitive dysfunction, which may negatively affect motor imagery. In this cross-sectional study, we explored differences in motor imagery of walking performance between pwMS (n = 20, age = 57.1 (SD = 8.6) years, 55% female) and age- and sex-matched healthy controls (n = 20, age = 58.1 (SD = 7.0) years, 60% female). Participants underwent mental chronometry assessments, a subset of motor imagery, which evaluated the difference between imagined and actual walking times across four walking tasks of increasing difficulty (i.e., large/narrow-width walkway with/without obstacles). Raw and absolute mental chronometry (A-MC) measures were recorded in single- (ST) and dual-task (DT) conditions. In ST conditions, pwMS had higher A-MC scores across all walking conditions (p ≤ 0.031, η² ≥ 0.119), indicating lower motor imagery ability compared to healthy controls. During DT, all participants tended to underestimate their walking ability (3.38 ± 6.72 to 5.63 ± 9.17 s). However, after physical practice, pwMS were less able to adjust their imagined walking performance compared to healthy controls. In pwMS, A-MC scores were correlated with measures of balance confidence (ρ = −0.629, p < 0.01) and the self-reported expanded disability status scale (ρ = 0.747, p < 0.01). While the current study revealed that pwMS have lower motor imagery of walking performance compared to healthy individuals, further work is necessary to examine how the disassociation between mental chronometry and actual performance relates to quality of life and well-being.

ADGRL3, FGF1 and DRD4: Linkage and Association with Working Memory and Perceptual Organization Candidate Endophenotypes in ADHD

Attention deficit hyperactivity disorder (ADHD) is a highly heritable neurobehavioral disorder that affects children worldwide, with detrimental long-term consequences in affected individuals. ADHD-affected patients display visual-motor and visuospatial abilities and skills that depart from those exhibited by non-affected individuals and struggle with perceptual organization, which might partially explain impulsive responses. Endophenotypes (quantifiable or dimensional constructs that are closely related to the root cause of the disease) might provide a more powerful and objective framework for dissecting the underlying neurobiology of ADHD than that of categories offered by the syndromic classification. In here, we explore the potential presence of the linkage and association of single-nucleotide polymorphisms (SNPs), harbored in genes implicated in the etiology of ADHD (ADGRL3, DRD4, and FGF1), with cognitive endophenotypes related to working memory and perceptual organization in 113 nuclear families. These families were ascertained from a geographical area of the Caribbean coast, in the north of Colombia, where the community is characterized by its ethnic diversity and differential gene pool. We found a significant association and linkage of markers ADGRL3-rs1565902, DRD4-rs916457 and FGF1-rs2282794 to neuropsychological tasks outlining working memory and perceptual organization such as performance in the digits forward and backward, arithmetic, similarities, the completion of figures and the assembly of objects. Our results provide strong support to understand ADHD as a combination of working memory and perceptual organization deficits and highlight the importance of the genetic background shaping the neurobiology, clinical complexity, and physiopathology of ADHD. Further, this study supplements new information regarding an ethnically diverse community with a vast African American contribution, where ADHD studies are scarce.

Evaluating the relationship between working memory and information processing speed in multiple sclerosis

The aim of the present study was to evaluate the effect of information processing speed on the functioning of specific working memory components, i.e. phonological loop, visuospatial sketchpad, central executive and episodic buffer. Cognitive tasks that assess working memory ("word lists recall" for the phonological loop, "block recall" for the spatial component of visuospatial sketchpad, "listening recall" for the central executive and "immediate story recall" for the episodic buffer) and information processing speed (symbol digit modalities test- oral form) were administered to 38 patients with multiple sclerosis. Results showed that the central executive and episodic buffer components were significantly related to information processing speed. However, when age was included in the regression model, information processing speed significantly predicted only the episodic buffer scores. Further research on the relationship between the episodic buffer and information processing speed is recommended.