Rapid serial processing in patients with multiple sclerosis: the role of peripheral deficits

Women in the field of multiple sclerosis: How they contributed to paradigm shifts

History is full of women who made enormous contributions to science. While there is little to no imbalance at the early career stage, a decreasing proportion of women is found as seniority increases. In the multiple sclerosis (MS) field, 44% of first authors and only 35% of senior authors were female. So, in this review, we highlight ground-breaking research done by women in the field of MS, focusing mostly on their work as principal investigators. MS is an autoimmune disorder of the central nervous system (CNS), with evident paradigm shifts in the understating of its pathophysiology. It is known that the immune system becomes overactivated and attacks myelin sheath surrounding axons. The resulting demyelination disrupts the communication signals to and from the CNS, which causes unpredictable symptoms, depending on the neurons that are affected. Classically, MS was reported to cause mostly physical and motor disabilities. However, it is now recognized that cognitive impairment affects more than 50% of the MS patients. Another shifting paradigm was the involvement of gray matter in MS pathology, formerly considered to be a white matter disease. Additionally, the identification of different T cell immune subsets and the mechanisms underlying the involvement of B cells and peripheral macrophages provided a better understanding of the immunopathophysiological processes present in MS. Relevantly, the gut-brain axis, recognized as a bi-directional communication system between the CNS and the gut, was found to be crucial in MS. Indeed, gut microbiota influences not only different susceptibilities to MS pathology, but it can also be modulated in order to positively act in MS course. Also, after the identification of the first microRNA in 1993, the role of microRNAs has been investigated in MS, either as potential biomarkers or therapeutic agents. Finally, concerning MS therapeutical approaches, remyelination-based studies have arisen on the spotlight aiming to repair myelin loss/neuronal connectivity. Altogether, here we emphasize the new insights of remarkable women that have voiced the impact of cognitive impairment, white and gray matter pathology, immune response, and that of the CNS-peripheral interplay on MS diagnosis, progression, and/or therapy efficacy, leading to huge breakthroughs in the MS field.

Cognition in older patients with multiple sclerosis compared to patients with amnestic mild cognitive impairment and healthy older adults

OBJECTIVE

Progress in the treatment of multiple sclerosis (MS) has resulted in larger numbers of patients living to an advanced age, but little is known about the cognitive status of these individuals. The primary purpose of this study was to identify differences in the cognitive performance between elderly individuals with MS and those with amnestic mild cognitive impairment (aMCI).

METHOD

Three groups ranging in age from 60 to 80 were compared: patients with MS (n = 64), patients with aMCI (n = 58), and healthy adults (n = 70). All participants completed a standard neuropsychological test battery that evaluated domains of attention, processing speed, executive function, memory, language, and visual spatial function.

RESULTS

Compared to age- and gender-matched healthy controls, elderly MS patients exhibited a pattern of cognitive impairment centering on information processing speed and memory that was consistent with the deficits observed in other studies of MS patients regardless of age. Compared to aMCI patients, the MS patients exhibited worse performance on measures of processing speed, but better performance on a measure of memory under cued conditions (Selective Reminding Test), a nonspeeded measure of language (Boston Naming Test), and measures of executive function with processing speed statistically controlled (Trail Making Test, Stroop Test).

CONCLUSIONS

Differences on neuropsychological measures can serve to distinguish aMCI from MS-related cognitive impairment in older patients, but it is essential that these measures control for the deficit in processing speed that is such a primary feature of MS. (PsycINFO Database Record

Information processing speed in multiple sclerosis: Past, present, and future

BACKGROUND

Information processing speed (IPS) is a prevalent cognitive impairment in multiple sclerosis (MS).

OBJECTIVES

This review aims to summarize the methods applied to assess IPS in MS and its theoretical conceptualization. A PubMed search was performed to select articles published between 1 January 2004 and 31 December 2013, resulting in 157 articles included.

RESULTS

The majority (54%) of studies assessed IPS with heterogeneous samples (several disease courses). Studies often report controlling for presence of other neurological disorders (60.5%), age (58.6%), education (51.6%), alcohol history (47.8%), or use of steroids (39.5%). Potential confounding variables, such as recent relapses (50.3%), history of developmental disorders (19.1%), and visual problems (29.9%), were often neglected. Assessments used to study IPS were heterogeneous (ranging from simple to complex tasks) among the studies under review, with 62 different tasks used. Only 9.6% of articles defined the construct of IPS and 22.3% discussed IPS in relation to a theoretical model.

FUTURE DIRECTIONS

The challenges for the upcoming decade include clarification of the definition of IPS as well as its theoretical conceptualization and a consensus on assessment. Based on the results obtained, we propose a new theoretical model, the tri-factor model of IPS.

Normative data for the Stroop color word test for a North American population

BACKGROUND

Cognitive impairment in multiple sclerosis (MS) often involves attentional deficits. The Stroop colour word test, a measure of attention, lacks current normative data for an english-speaking North american MS population. Further some authors suggest the Stroop actually measures processing speed.

OBJECTIVE

To generate normative data for the Stroop colour word test that can be used for a Canadian or North american MS population and to examine the relationship between processing speed tests--the Paced auditory Serial addition Test (PASAT) and Symbol Digit Modalities Test (SDMT)--and the Stroop.

RESULTS

Data from 146 healthy subjects aged 18-56 was collected. age was significantly although weakly correlated with general intelligence (r=0.168, p=0.043) assessed with the North american adult Reading Test (NAART), and education (r=-0.313, p<0.001). No demographic variables were associated with SDMT or PASAT. age had a low-moderate negative correlation (r=-0.403, p<0.001) with Stroop scores. The mean (±standard deviation, SD) Stroop score was 45.4(10.4). The z-score can thus be calculated as [(X-45.4)/10.4]. if adjusted for age, Xadj = [X-(-0.47)(age-37.5)] and is substituted for X. in a comparison MS population consisting of 75 randomly selected patients from the MS Cognitive clinic, Stroop and PASAT performance were not related. a relationship existed between Stroop and SDMT scores but only 12.2% of the Stroop score variance was explained by the SDMT. Therefore, the Stroop measures selective attention independently of processing speed.

CONCLUSION

This data can be used to determine impaired attention in MS patients.

Données normatives pour le test mot-couleur de Stroop chez une population nord-américaine.

Reaction time and rapid serial processing measures of information processing speed in multiple sclerosis: complexity, compounding, and augmentation

Information processing speed is frequently cited as the primary cognitive domain impacted by multiple sclerosis (MS) and is usually evaluated with reaction time (RT) or rapid serial processing (RSP) measures. The present study compared the efficacy of RT and RSP measures to distinguish between patients with MS (N = 42) and healthy controls (N = 40). The RT measure was patterned after the Computerized Tests of Information Processing and included measures of simple, choice, and semantic RT. The RSP measures consisted of the Symbol Digit Modalities Test (SDMT) and the Stroop Test. Substantial differences in information processing speed between patients and controls were found on all tests, with slightly larger effect sizes for RSP measures than RT measures and for the SDMT than the Stroop Test. Binary logistic regression analyses showed RSP measures performed better than RT measures at distinguishing patients from controls, and likewise, the SDMT score performed better than the scores derived from the Stroop Test. Results are discussed in the context of three effects associated with common measures of processing speed: complexity, compounding, and augmentation.

Global processing speed in children with low reading ability and in children and adults with typical reading ability: exploratory factor analytic models

PURPOSE

To investigate processing speed as a latent dimension in children with dyslexia and children and adults with typical reading skills.

METHOD

Exploratory factor analysis (FA) was based on a sample of multigenerational families, each ascertained through a child with dyslexia. Eleven measures--6 of them timed--represented verbal and nonverbal processes, alphabet writing, and motor sequencing in the hand and oral motor system. FA was conducted in 4 cohorts (all children, a subset of children with low reading scores, a subset of children with typical reading scores, and adults with typical reading scores; total N = 829).

RESULTS

Processing speed formed the first factor in all cohorts. Both measures of motor sequencing speed loaded on the speed factor with the other timed variables. Children with poor reading scores showed lower speed factor scores than did typical peers. The speed factor was negatively correlated with age in the adults.

CONCLUSIONS

The speed dimension was observed independently of participant cohort, gender, and reading ability. Results are consistent with a unified theory of processing speed as a quadratic function of age in typical development and with slowed processing in poor readers.

The impact of multiple sclerosis on patients' performance on the Stroop Test: processing speed versus interference

Deficits in multiple sclerosis (MS) patients' performance on the Stroop Test have been attributed to problems with processing speed and selective attention. Data for 248 MS patients and 178 controls on all three trials of the Stroop were combined using various scoring formulas proposed for assessing processing speed, color difficulty, and interference. The greatest differences between patients and controls involved processing speed. Formulas purporting to measure interference yielded highly inconsistent results: Significant differences between groups were found on two of the most common measures but were in opposite directions. This contradiction stems from the failure of both measures to effectively control for processing speed when assessing interference. Three alternative measures, using relative, ratio, and residualized scores, offer much better indices of interference. When assessed with these alternative measures, interference increased with age, but no differences between patients and controls were found. Difficulties that MS patients have with the Stroop Test are confined to processing speed.