The relationship between executive functions and fluid intelligence in multiple sclerosis

Examining the Stability and Predictive Utility of Across- and Within-Domain Intra-Individual Variability in Mild Cognitive Impairment

OBJECTIVE

Dispersion is a form of intra-individual variability across neuropsychological tests that has been shown to predict cognitive decline. However, few studies have investigated the stability and predictive utility of both across- and within-domain dispersion. The current study aims to fill these gaps in the literature by examining multiple indices of dispersion in a longitudinal clinical sample of individuals diagnosed with mild cognitive impairment (MCI) at baseline.

METHOD

Two hundred thirty-eight MCI patients from a cognitive disorders clinic underwent testing at baseline and after approximately 1.5 years. Linear regression was used to examine whether baseline across- and within-domain dispersion predicted cognitive decline in individuals whose diagnostic classification progressed to dementia (i.e., MCI-Decline) and those who retained an MCI diagnosis at follow-up (i.e., MCI-Stable). Cognitive decline was operationalized dichotomously using group status and continuously using standardized regression-based (SRB) z-scores.

RESULTS

Dispersion variables at baseline and follow-up were positively correlated in both groups, with the exception of within-domain executive functioning and language dispersion in the MCI-Decline group. None of the dispersion variables predicted diagnostic conversion to MCI. Using SRB z-scores, greater across-domain dispersion predicted greater overall cognitive decline at follow-up, but this was not the case for within-domain variables with the exception of visuospatial skills.

CONCLUSIONS

Results suggest that across- and within-domain dispersion are relatively stable across time, and that across-domain dispersion is predictive of subtle cognitive decline in patients with MCI. However, these results also highlight that findings may differ based on the tests included in dispersion calculations.

A systematic review and meta-analysis of socio-cognitive impairments in multiple sclerosis

Socio-cognitive impairment is frequent in multiple sclerosis (MS). However, little is known about the relationship between other potentially relevant clinical symptoms (i.e., cognition, depression, fatigue) and the degree of socio-cognitive impairment, and neural mechanisms underlying socio-cognitive deficits in MS. Therefore, we meta-analytically quantified socio-cognitive impairment in MS. A systematic literature search in MEDLINE Ovid, Web of Science Core Collection, CENTRAL, and PsycInfo was conducted until December 2022. Studies investigating affective or cognitive theory of mind (a/cToM), visual perspective taking (VPT) and social decision making (SDM) in MS patients relative to healthy controls were included. Risk-of-bias (RoB) was assessed using the CLARITY group "Tool for Assessing RoB in Cohort Studies". Mediation analysis investigated the contribution of clinical symptoms to socio-cognitive impairment. In total, n = 8534 studies were screened, 58 were included in the systematic review, 27 in the meta-analyses. Most studies were rated with a moderate RoB. Meta-analyses confirmed impairment of both aToM and cToM in MS patients, with larger effect sizes for aToM. Mediation analysis demonstrated that higher levels of fatigue selectively predicted the degree of cToM impairment. There was insufficient data available to quantify impairment in other socio-cognitive domains. Fourteen structural and functional imaging studies were identified and characterized by substantial heterogeneity. Summarized, this study confirmed substantial socio-cognitive impairment in MS and highlights the potential exacerbating role of comorbid clinical symptoms. We identify several evidence gaps that need to be addressed in future large-scale studies using comprehensive and coordinated assessments of socio-cognitive parameters, potential mediators, and neural correlates.Trial registration: The pre-registered review protocol can be assessed at www.crd.york.ac.uk/PROSPERO/ (ID: CRD42020206225).

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.

Language impairments in people with autoimmune neurological diseases: A scoping review

INTRODUCTION

Autoimmune neurological diseases (ANDs) are a specific type of autoimmune disease that affect cells within the central and peripheral nervous system. ANDs trigger various physical/neuropsychiatric symptoms. However, language impairments in people with ANDs are not well characterized. Here we aimed to determine the kinds of language impairment that most commonly emerge in 10 ANDs, the characteristics of the patients (demographic, neurological damage), and the assessment methods used.

METHODS

We followed the PRISMA Extension for Scoping Reviews (PRISMA-ScR). PubMed and Google Scholar were searched. We used a list of search terms containing 10 types of ANDs (e.g., multiple sclerosis, acute disseminated encephalomyelitis) in combination with the terms aphasia, dysphasia, fluency, language, listening, morphology, phonology, pragmatics, reading, semantics, speaking, syntax, writing. The reference lists and citations of the relevant papers were also investigated. The type of AND, patient characteristics, neurological damage and examination technique, language tests administered, and main findings were noted for each study meeting the inclusion criteria.

RESULTS

We found 171 studies meeting our inclusion criteria. These comprised group studies and case studies. Language impairments differed largely among types of ANDs. Neurological findings were mentioned in most of the papers, but specific language tests were rarely used.

CONCLUSIONS

Language symptoms in people with ANDs are commonly reported. These are often not full descriptions or only focus on specific time points in the course of the disease. Future research needs to assess specific language functions in people with ANDs and relate their language impairments to brain damage at different stages of disease evolution.

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.

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.

A promising cognitive screener in multiple sclerosis: The NIH toolbox cognition battery concords with gold standard neuropsychological measures

BACKGROUND

Routine cognitive screening is a priority in MS clinical care. The National Institutes of Health Toolbox (NIHTB) Cognition Battery is a 30-min instrument validated in neurological populations excluding MS.

OBJECTIVES

To assess construct validity of NIHTB tests and compare classification of cognitive impairment with gold-standard tests. To evaluate relationships between fluid cognition and clinical measures.

METHODS

Eighty-seven individuals, aged 30-59 years, completed the NIHTB, Minimal Assessment of Cognitive Function in MS (MACFIMS), Wechsler Adult Intelligence Scale-IV subtests, and measures of disease severity, depression, and fatigue.

RESULTS

The NIHTB showed adequate convergent validity for processing speed, working memory, and episodic memory. Although fluid cognition scores from the NIHTB and MACFIMS classified a similar proportion of participants as cognitively impaired, the two batteries differed in which individuals were classified as impaired versus preserved. NIHTB fluid cognition was inversely correlated with disease severity but not related to depression or fatigue.

CONCLUSIONS

The NIHTB concords with gold-standard measures, and classifies cognitive impairment at similar rates to the MACFIMS. Adjusted NIHTB fluid cognition was negatively associated with disease severity suggesting clinical utility. Psychometric validation of the NIHTB in clinical practice will elucidate its promise as a cognitive screener in MS.

Perspective taking deficits and their relationship with theory of mind abilities in patients with relapsing-remitting multiple sclerosis (RRMS)

Introduction and objectives: In recent years, research has reported that between 45% and 70% of patients with Multiple Sclerosis (MS) have cognitive deficits, the most prominent being those associated with the frontal lobe. Among these deficits, we can find Theory of Mind (ToM), which is the ability to infer feelings and thoughts of others. Although it has been suggested that ToM relies on more basic skills, such as perspective taking (PT), no studies have investigated this association in patients with MS. The aim of this study was to investigate PT abilities in patients with MS and to establish their relationship with ToM deficits. Material and methods: 36 patients with relapsing-remitting multiple sclerosis (RRMS) and 42 healthy controls matched by age, sex and educational level were evaluated. Both groups were tested to estimate premorbid and current intellectual capacity, PT, ToM (Reading the Mind in the Eyes Test -RMET- and Faux Pas) and complementary scales (fatigue, depression and disability). Results: Patients with RRMS presented significant differences from controls in both PT and ToM tests. The PT test showed positive correlation with RMET, one of our ToM tests. Conclusion: The results show that there is a relationship between ToM and PT abilities. Our findings are of clinical and academic relevance to both the assessment and interpretation as well as the rehabilitation of social deficits in MS.

Social cognition in multiple sclerosis and its subtypes: A meta-analysis

BACKGROUND

Multiple sclerosis (MS) is an immune-mediated demyelinating disease that disrupts several social cognitive abilities, including the theory of mind (ToM) and facial emotion recognition (FER). It is unclear how specific ToM subcomponents, including cognitive and affective ToM, are affected in patients with MS and the social cognitive abilities in MS subtypes.

METHODS

A search of PubMed, Web of Science, and Embase databases was conducted until June 2020. Effect sizes were calculated using Hedges g with a random-effects model.

RESULTS

A total of 45 studies were included. Relative to health controls (HCs), patients with MS and its subtypes (including relapsing-remitting MS [RRMS] and progressive MS) exhibited impairments in ToM (g = -0.77, g = -0.70, g = -0.75, respectively), cognitive ToM (g = -0.72, g = -0.83, g = -0.73, respectively), affective ToM (g = -0.84, g = -0.63, g = -0. 50, respectively), and FER (g = -0.62, g = -0.53, g = -1.07, respectively). In addition, there was no difference between progressive primary MS and secondary progressive MS in overall ToM, cognitive ToM, affective ToM, and FER. Compared to patients with RRMS, patients with progressive MS showed no difference in overall ToM, cognitive ToM, and affective ToM but had more serious defects in FER (g = -0.57).

CONCLUSIONS

These quantitative results indicate that patients with MS and its subtypes have a differential impairment of the core aspects of social cognitive processing (including ToM and FER), which may help develop the structured social cognitive interventions in MS.

Empathy and Theory of Mind in Multiple Sclerosis: A Meta-Analysis

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. Studies have shown that MS disrupts several social cognitive abilities [including empathy and theory of mind (ToM)]. Overall ToM deficits in MS are well documented, but how the specific ToM subcomponents and empathic capacity are affected remains unclear. For this meta-analysis, we searched PubMed, Web of Science, and Embase from inception to July 2020. Effect sizes were calculated using Hedges g with a random-effects model. Thirty-three studies were included. Relative to healthy controls (HCs), patients with MS were moderately impaired in overall empathy (g = -0.67), overall ToM (g = -74), cognitive ToM (g = -0.72), and the overlapping domains of cognitive empathy/affective ToM (g = -0.79); no group differences were identified for affective empathy (g = -0.19). Compared with HCs, patients with relapsing-remitting MS (RRMS) and progressive MS were impaired in overall empathy, overall ToM, cognitive ToM, and cognitive empathy/affective ToM, without significant RRMS-progressive MS differences in impairment degree. We conducted the first meta-analytic review investigating the empathy and ToM functioning patterns in patients with MS and examined the overlapping and distinct subcomponents of these constructs. The findings suggest differential impairment of the core aspects of social cognitive processing in patients with MS, which may importantly inform the development of structured social cognitive MS interventions.