The PASAT performance among patients with multiple sclerosis: analyses of responding patterns using different scoring methods

Temporal Pattern of Cortical Hypoxia in Multiple Sclerosis and Its Significance on Neuropsychological and Clinical Measures of Disability

OBJECTIVE

Multiple sclerosis (MS) is a degenerative disease of the central nervous system (CNS) characterized by inflammation, demyelination, and axonal damage. It has been hypothesized that hypoxia plays a role in the pathogenesis of MS. This study was undertaken to investigate the reproducibility of non-invasively measured cortical microvascular hemoglobin oxygenation (St O2 ) using frequency domain near-infrared spectroscopy (fdNIRS), investigate its temporal pattern of hypoxia in people with MS (pwMS), and its relationship with neurocognitive function and mood.

METHODS

We investigated the reproducibility of fdNIRS measurements. We measured cortical hypoxia in pwMS, and the relationships between St O2 , neurocognitive function, fatigue, and measures of physical disability. Furthermore, we cataloged the temporal pattern of St O2 measured at 1-week intervals for 4 weeks, and at 8 weeks and ~1 year.

RESULTS

We show that fdNIRS parameters were highly reproducible in 7 healthy control participants measured over 6 days (p > 0.05). There was low variability between and within subjects. In line with our previous findings, we show that 33% of pwMS (n = 88) have cortical microvascular hypoxia. Over 8 weeks and at ~1 year, St O2 values for normoxic and hypoxic groups did not change significantly. There was no significant association between cognitive function and St O2 . This conclusion should be revisited as only a small proportion of the relapsing-remitting MS group (21%) was cognitively impaired.

INTERPRETATION

The fdNIRS parameters have high reproducibility and repeatability, and we have demonstrated that hypoxia in MS is a chronic condition, lasting at least a year. The results show a weak relationship between cognitive functioning and oxygenation, indicating future study is required. ANN NEUROL 2023;94:1067-1079.

Brain hypoxia, neurocognitive impairment, and quality of life in people post-COVID-19

OBJECTIVE

Systemic hypoxia occurs in COVID-19 infection; however, it is unknown if cerebral hypoxia occurs in convalescent individuals. We have evidence from other conditions associated with central nervous system inflammation that hypoxia may occur in the brain. If so, hypoxia could reduce the quality of life and brain function. This study was undertaken to assess if brain hypoxia occurs in individuals after recovery from acute COVID-19 infection and if this hypoxia is associated with neurocognitive impairment and reduced quality of life.

METHODS

Using frequency-domain near-infrared spectroscopy (fdNIRS), we measured cerebral tissue oxygen saturation (S_tO₂) (a measure of hypoxia) in participants who had contracted COVID-19 at least 8 weeks prior to the study visit and healthy controls. We also conducted neuropsychological assessments and health-related quality of life assessments, fatigue, and depression.

RESULTS

Fifty-six percent of the post-COVID-19 participants self-reported having persistent symptoms (from a list of 18), with the most reported symptom being fatigue and brain fog. There was a gradation in the decrease of oxyhemoglobin between controls, and normoxic and hypoxic post-COVID-19 groups (31.7 ± 8.3 μM, 27.8 ± 7.0 μM and 21.1 ± 7.2 μM, respectively, p = 0.028, p = 0.005, and p = 0.081). We detected that 24% of convalescent individuals' post-COVID-19 infection had reduced S_tO₂ in the brain and that this relates to reduced neurological function and quality of life.

INTERPRETATION

We believe that the hypoxia reported here will have health consequences for these individuals, and this is reflected in the correlation of hypoxia with greater symptomology. With the fdNIRS technology, combined with neuropsychological assessment, we may be able to identify individuals at risk of hypoxia-related symptomology and target individuals that are likely to respond to treatments aimed at improving cerebral oxygenation.

NIRS Studies Show Reduced Interhemispheric Functional Connectivity in Individuals with Multiple Sclerosis That Exhibit Cortical Hypoxia

Many with multiple sclerosis (MS) have low cortical microvascular oxygen levels (hypoxia), which have been previously proposed to exacerbate inflammation in MS. We do not know if hypoxia impacts or relates to brain function. We hypothesise that within the MS population, those who have hypoxia may show reduced brain functional connectivity (FC). We recruited 20 MS participants and grouped them into normoxic and hypoxic groups (n = 10 in each group) using frequency-domain near-infrared spectroscopy (fdNIRS). Functional coherence of the haemodynamic signal, quantified with functional near-infrared spectroscopy (fNIRS) was used as a marker of brain function and was carried out during resting-state, finger-tapping, and while completing two neurocognitive tasks. Reduced FC was detected in the hypoxic MS group. fNIRS measures of haemodynamic coherence in MS could be a biomarker of functional impairment and/or disease progression.

Validation of Discrete and Regression-Based Performance and Cognitive Fatigability Normative Data for the Paced Auditory Serial Addition Test in Multiple Sclerosis

Cognitive fatigability is an objective performance decrement that occurs over time during a task requiring sustained cognitive effort. Although cognitive fatigability is a common and debilitating symptom in multiple sclerosis (MS), there is currently no standard for its quantification. The objective of this study was to validate the Paced Auditory Serial Addition Test (PASAT) discrete and regression-based normative data for quantifying performance and cognitive fatigability in an Ontario-based sample of individuals with MS. Healthy controls and individuals with MS completed the 3″ and 2″ versions of the PASAT. PASAT performance was measured with total correct, dyad, and percent dyad scores. Cognitive fatigability scores were calculated by comparing performance on the first half (or third) of the task to the last half (or third). The results revealed that the 3″ PASAT was sufficient to detect impaired performance and cognitive fatigability in individuals with MS given the increased difficulty of the 2″ version. In addition, using halves or thirds for calculating cognitive fatigability scores were equally effective methods for detecting impairment. Finally, both the discrete and regression-based norms classified a similar proportion of individuals with MS as having impaired performance and cognitive fatigability. These newly validated discrete and regression-based PASAT norms provide a new tool for clinicians to document statistically significant cognitive fatigability in their patients.

Memantine for Multiple Sclerosis: A Systematic Review and Meta-Analysis of Randomized Trials

Background: Multiple sclerosis (MS), a disabling demyelinating disease of the central nervous system, is associated with cognitive impairment, spasticity, and fatigue. There are still no established guidelines on the management of MS-related sequela. Memantine has the potential to reduce glutamate toxicity, thereby reducing consequent cognitive impairment, spasticity, and fatigue.

Objectives: This study aims to determine the efficacy and safety of memantine in preventing cognitive impairment, reducing spasticity and fatigue, and controlling disability in MS patients through a review of relevant randomized trials.

Methods: MEDLINE, CENTRAL, Scopus, Embase, LILACS, ClinicalTrials.gov, and HERDIN were searched from inception to May 2020 for relevant trials.

Results: The search yielded 203 articles; four studies were included in the analysis. Pooled evidence shows that memantine compared with placebo does not significantly improve PASAT, ASS, MFIS, and EDSS scores of patients with MS. Memantine is associated with mild adverse drug events such as dizziness, fatigue, and anxiety.

Conclusion: There is not enough evidence to support the efficacy of memantine in preventing cognitive decline, controlling spasticity, reducing fatigue, and preventing disability. Future researches should consider the different MS subtypes, effect of co-administration of disease-modifying therapies, longer duration of administration, and more sensitive outcome measures to evaluate the potential benefit of memantine in MS.

Does type of active workstation matter? A randomized comparison of cognitive and typing performance between rest, cycling, and treadmill active workstations

Active workstations are associated with improved health outcomes, but differences in cognitive and typing outcomes between the types of active workstations are unclear. We addressed two main questions: (1) Are there differences in cognitive and typing performance between seated and active workstations? (2) Are there differences in cognitive and typing performance between cycling and treadmill workstations, specifically? Participants included 137 healthy young adults (74 female, mean age = 20.8 years) who completed two sessions. At session one (baseline), all participants completed cognitive and typing tests including the Rey-Auditory Verbal Learning Test, Paced Auditory Serial Addition Test, a typing test, and a flanker task while sitting at rest. At session two, participants were randomized to an active workstation group (treadmill or cycling desk) during which they performed the tests listed above in a randomized fashion, using alternate versions when available. Participants showed significantly better attention and cognitive control scores during the active session as compared to the seated session, but worse verbal memory scores during the active session. Participants were faster and more accurate at typing during the active session relative to the seated session. There were no significant differences between cycling or treadmill workstations on any cognitive or typing outcomes. Improvements during active sessions may be influenced by practice effects, although alternate forms were used when possible. We conclude that active workstations do not seem to largely impact cognitive abilities, with the exception of a slight decrease in verbal memory performance. Findings suggest active workstations, whether walking or cycling, are useful to improve physical activity, particularly when completing tasks that do not require verbal memory recall.

The Dyad-Adaptive Paced Auditory Serial Addition Test (DA-PASAT): Normative data and the effects of repeated testing, simulated malingering, and traumatic brain injury

The Paced Auditory Serial Addition Test (PASAT) is widely used to evaluate processing speed and executive function in patients with multiple sclerosis, traumatic brain injury, and other neurological disorders. In the PASAT, subjects listen to sequences of digits while continuously reporting the sum of the last two digits presented. Four different stimulus onset asynchronies (SOAs) are usually tested, with difficulty increasing as SOAs are reduced. Ceiling effects are common at long SOAs, while the digit delivery rate often exceeds the subject’s processing capacity at short SOAs, causing some subjects to stop performing altogether. In addition, subjects may adopt an “alternate answer” strategy at short SOAs, which reduces the test’s demands on working-memory and processing speed. Consequently, studies have shown that the number of dyads (consecutive correct answers) is a more sensitive measure of PASAT performance than the overall number of correct sums. Here, we describe a 2.5-minute computerized test, the Dyad-Adaptive PASAT (DA-PASAT), where SOAs are adjusted with a 2:1 staircase, decreasing after each pair of correct responses and increasing after misses. Processing capacity is reflected in the minimum SOA (minSOA) achieved in 54 trials. Experiment 1 gathered normative data in two large populations: 1617 subjects in New Zealand ranging in age from 18 to 65 years, and 214 Californians ranging in age from 18 to 82 years. Minimum SOAs were influenced by age, education, and daily hours of computer-use. Minimum SOA z-scores, calculated after factoring out the influence of these factors, were virtually identical in the two control groups, as were response times (RTs) and dyad ratios (the proportion of hits occurring in dyads). Experiment 2 measured the test-retest reliability of the DA-PASAT in 44 young subjects who underwent three test sessions at weekly intervals. High intraclass correlation coefficients (ICCs) were found for minSOAs (0.87), response times (0.76), and dyad ratios (0.87). Performance improved across test sessions for all measures. Experiment 3 investigated the effects of simulated malingering in 50 subjects: 42% of simulated malingerers produced abnormal (p< 0.05) minSOA z-scores. Simulated malingerers with abnormal scores were distinguished with 87% sensitivity and 69% specificity from control subjects with abnormal scores by excessive differences between training performance and the actual test. Experiment 4 investigated patients with traumatic brain injury (TBI): patients with mild TBI performed within the normal range while patients with severe TBI showed deficits. The DA-PASAT reduces the time and stress of PASAT assessment while gathering sensitive measures of dyad processing that reveal the effects of aging, malingering, and traumatic brain injury on performance.

Validation of the PASAT in Argentina

The Paced Auditory Serial Addition Test (PASAT) is one of the most used neuropsychological tests to assess information processing speed and working memory in brain injured patients. This study was carried out with the purpose of obtaining normative data for the PASAT-3″ in a healthy Argentinean population, which would result in a reference control population. The PASAT-3″ was administered in a sample of 296 healthy voluntary subjects, born and living in Argentina. The age range went from 20 to 70 years-old. The level of education was 0 to 13 or more years of schooling. The sample obtained a mean of 44.60 (SD = 10.72) in the PASAT-3″. It was found that the score obtained in the PASAT-3″ was related to the age and the level of instruction of the participants. Their performance diminished as age increased and, conversely, it increased as the level of instruction was higher. Normative data was obtained for a Latin American population from Argentina. Percentile distributions obtained by decades of age and different levels of education should be considered as useful reference values for clinicians and investigators when applying the PASAT-3″ to assess cognitive function in different pathologies.

Cognitive and typing outcomes measured simultaneously with slow treadmill walking or sitting: implications for treadmill desks

Purpose

This study compared cognitive (attention, learning, and memory) and typing outcomes during slow treadmill walking or sitting. Seventy-five healthy individuals were randomly assigned to a treadmill walking group (n=37; 23 female) or sitting group (n=38; 17 female).

Methods

The treadmill walking group completed a series of tests while walking at 1.5 mph. The sitting group performed the same tests while sitting at a standard desk. Tests performed by both groups included: the Rey Auditory Verbal Learning Test and a modified version of the Paced Auditory Serial Attention Test. In addition, typing performance was evaluated.

Results

Participants in the treadmill walking group performed worse on the Rey Auditory Verbal Learning Test for total learning than the sitting group; the main effect was significant (F(1,73)=4.75, p=0.03, η_p²=0.06); however, short- and long-delay recall performance did not differ between groups (p>0.05). For the Paced Auditory Serial Attention Test, total number of correct responses was lower in the treadmill walking group relative to the sitting group; the main effect was significant (F(1,73)=4.97, p=0.03, η_p²=0.06). The performance of both groups followed the same learning slope (Group x Trial interactions were not significant) for the Rey Auditory Verbal Learning Test and Paced Auditory Serial Attention Test. Individuals in the treadmill walking group performed significantly worse for all measures of typing (p<0.05).

Conclusion

Walking on a treadmill desk may result in a modest difference in total learning and typing outcomes relative to sitting, but those declines may not outweigh the benefit of the physical activity gains from walking on a treadmill.

Wavelet-Based Scalar-on-Function Finite Mixture Regression Models

Classical finite mixture regression is useful for modeling the relationship between scalar predictors and scalar responses arising from subpopulations defined by the di ering associations between those predictors and responses. The classical finite mixture regression model is extended to incorporate functional predictors by taking a wavelet-based approach in which both the functional predictors and the component-specific coefficient functions are represented in terms of an appropriate wavelet basis. By using the wavelet representation of the model, the coefficients corresponding to the functional covariates become the predictors. In this setting, there are typically many more predictors than observations. Hence a lasso-type penalization is employed to simultaneously perform feature selection and estimation. Specification of the model is discussed and a fitting algorithm is provided. The wavelet-based approach is evaluated on synthetic data as well as applied to a real data set from a study of the relationship between cognitive ability and di usion tensor imaging measures in subjects with multiple sclerosis.

Auto-titrating continuous positive airway pressure treatment for obstructive sleep apnoea after acute quadriplegia (COSAQ): study protocol for a randomized controlled trial

Background

Quadriplegia is a severe, catastrophic injury that predominantly affects people early in life, resulting in lifelong physical disability. Obstructive sleep apnoea is a direct consequence of quadriplegia and is associated with neurocognitive deficits, sleepiness and reduced quality of life. The usual treatment for sleep apnoea is nasal continuous positive airway pressure (CPAP); however, this is poorly tolerated in quadriplegia. To encourage patients to use this therapy, we have to demonstrate that the benefits outweigh the inconvenience. We therefore propose a prospective, multinational randomized controlled trial of three months of CPAP for obstructive sleep apnoea after acute quadriplegia.

Methods/design

Specialist spinal cord injury centres across Australia, New Zealand, the UK and Canada will recruit medically stable individuals who have sustained a (new) traumatic quadriplegia (complete or incomplete second cervical to first thoracic level lesions). Participants will be screened for obstructive sleep apnoea using full, portable sleep studies. Those with an apnoea hypopnoea index greater than 10 per hour will proceed to an initial three-night trial of CPAP. Those who can tolerate CPAP for at least 4 hours on at least one night of the initial trial will be randomized to either usual care or a 3-month period of auto-titrating CPAP. The primary hypothesis is that nocturnal CPAP will improve neuropsychological functioning more than usual care alone. The secondary hypothesis is that the magnitude of improvement of neuropsychological function will be predicted by the severity of baseline sleepiness measures, sleep fragmentation and sleep apnoea. Neuropsychological tests and full polysomnography will be performed at baseline and 3 months with interim measures of sleepiness and symptoms of autonomic dysfunction measured weekly. Spirometry will be performed monthly. Neuropsychological tests will be administered by blinded assessors. Recruitment commenced in July 2009.

Discussion

The results of this trial will demonstrate the effect of nocturnal CPAP treatment of obstructive sleep apnoea in acute quadriplegia. If CPAP can improve neurocognitive function after injury, it is likely that rehabilitation and subsequent community participation will be substantially improved for this group of predominantly young and severely physically disabled people.

Trial registration

Australian New Zealand Clinical Trial Registry ACTRN12605000799651

The effects of heat stress on cognition in persons with multiple sclerosis

Background: Heat sensitivity and cognitive deficits are typical manifestations of multiple sclerosis (MS). Although cognitive deficits are quite well characterized, practically no data exist on the effects of heat on cognitive performances in MS.

Objective: To assess the effects of short-term heat stress on cognitive functioning in subjects with MS.

Methods: A total of 23 heat-sensitive MS and 19 healthy control (HC) subjects participated. Moderate heat exposure took place in a Finnish sauna. Cognitive functioning was measured with tests of sustained attention and processing speed, the Paced Auditory Serial Addition Test (PASAT 3” and 2”) and the computerized visual vigilance test, before, during and after heat exposure.

Results: During the heat exposure, the core body temperature of the MS group rose significantly more ( p = 0.002) than that of the HC group. The heat stress worsened the performance of the MS group in the PASAT 3” ( p = 0.025) but not in the other cognitive measures. The performance in the PASAT 3” was reversed almost to the baseline level only 1- h after the heat exposure.

Conclusions: A significant increase in core body temperature during heat stress is associated with a mild and reversible worsening of the PASAT 3” performance, while visual vigilance performance seems to remain almost unaffected.

The effects of rivastigmine on processing speed and brain activation in patients with multiple sclerosis and subjective cognitive fatigue

Background: Cognitive decline and fatigue are typical in multiple sclerosis (MS). However, there is no official medication for either of these symptoms.

Objective: The purpose of this study was to estimate the effects of a single dose of rivastigmine on processing speed and associated brain activity in patients with MS and subjective cognitive fatigue.

Methods: Fifteen patients with MS and subjective cognitive fatigue and 13 healthy controls (HCs) matched for age, gender and education performed a neuropsychological assessment and functional (f)MRI. A modified version of the Paced Visual Serial Addition Test (mPVSAT) was used as the behavioural task during fMRIs. After the first scanning session, both groups were randomly divided into two subgroups receiving either rivastigmine or placebo. A single dose of rivastigmine or placebo was administrated double-blindly and 2.5 hours later the scanning was repeated.

Results: At baseline, the patients with MS showed slower processing speed in mPVSAT compared with the HCs. They also demonstrated stronger bilateral frontal activation after sustained cognitive effort than the HCs. Performance improvement and a further activation increase in the left anterior frontal cortex and additional activation in the right cerebellum were observed in patients who received rivastigmine but not in patients on placebo, or in HCs with placebo or rivastigmine.

Conclusion: These preliminary findings suggest that rivastigmine may improve cognitive processing speed by enhancing compensatory brain activation in patients with MS.

Fatigue and its relationships with cognitive functioning and depression in paediatric multiple sclerosis

BACKGROUND

There is limited information on fatigue and its clinical and psychosocial correlates in children and adolescents with multiple sclerosis (MS).

OBJECTIVE

To assess the relationships between fatigue, cognitive functioning and depression in paediatric MS.

METHODS

The study cohort consisted of patients with MS recruited for an Italian collaborative study on cognitive and psychosocial functioning in paediatric MS. The present assessment included evaluation of fatigue on the Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale, cognitive functioning on an extensive neuropsychological battery and depression on the Children's Depression Inventory (CDI). A psychiatric interview through the Kiddie-SADS-Present and Lifetime Version was also administered.

RESULTS

In total, 57 patients with relapsing-remitting MS were compared with 70 healthy controls. Percentages of fatigued patients ranged from 9% to 14% according to self-reports, and from 23% to 39% according to parent reports. Fatigue was significantly related with higher scores on the CDI (p < 0.03). Higher levels of self-reported cognitive fatigue were associated with impaired performance on a problem-solving test, whereas higher levels of parent-reported cognitive fatigue were associated with impairment on tests of verbal learning, processing speed, complex attention and verbal comprehension.

CONCLUSIONS

Our data show that fatigue can affect a sizeable proportion of paediatric MS patients, and confirm the association between fatigue and depressive symptoms in MS. They also highlight the difficulties of fatigue assessment in the paediatric population and provide a few clues to further research in the field.

Psychopathological and cognitive effects of therapeutic cannabinoids in multiple sclerosis: a double-blind, placebo controlled, crossover study

OBJECTIVES

To study possible psychopathological symptoms and cognitive deficits, abuse induction, as well as general tolerability and effects on quality of life, fatigue and motor function in cannabis-naïve patients with multiple sclerosis (MS) treated with a free-dose cannabis plant extract (Sativex).

METHODS

In an 8-week, randomized, double-blind, placebo-controlled, parallel group crossover trial, 17 cannabis-naïve patients with MS were assessed at baseline and at the end of the cannabis and placebo phases of the trial (each of 3 weeks) by means of Symptom Checklist-90 Revised, Self-rating Anxiety Scale, Multiple Sclerosis Functional Composite (of which 1 dimension is the Paced Auditory Serial Additional Test that was used to evaluate cognition), Visual Analogue Scale on health-related quality of life, Multiple Sclerosis Impact Scale-29, and Fatigue Severity Scale.

RESULTS

Postplacebo versus postcannabinoid scores showed that no significant differences could be detected on all the variables under study. A significant positive correlation was found between Delta-9-tetrahydrocannabinol blood levels and scores at the General Symptomatic Index and at the "interpersonal sensitivity," "aggressive behaviour," and "paranoiac tendencies" subscales of the Symptom Checklist-90 Revised. No serious adverse events, abuse tendencies, or direct withdrawal symptoms were reported. Increased desire for Sativex with secondary depression was reported in 1 subject.

CONCLUSIONS

Cannabinoid treatment did not induce psychopathology and did not impair cognition in cannabis-naïve patients with MS. However, the positive correlation between blood levels of Delta-9-tetrahydrocannabinol and psychopathological scores suggests that at dosages higher than those used in therapeutic settings, interpersonal sensitivity, aggressiveness, and paranoiac features might arise, although greater statistical power would be necessary to confirm this finding.

Transverse diffusivity of cerebral parenchyma predicts visual tracking performance in relapsing-remitting multiple sclerosis

This study investigated the relation between cerebral damage related to multiple sclerosis (MS) and cognitive decline as determined by two classical mental tracking tests. Cerebral damage in 15 relapsing-remitting MS patients was measured by diffusion tensor imaging (DTI). Fractional anisotropy, longitudinal and transverse diffusivity were defined in the cerebral parenchyma. Cognitive performance of the MS patients was assessed with the oral response format of the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT). A significant correlation was found between performance on the SDMT and the fractional anisotropy in the brain. This correlation was predominantly induced by transverse diffusivity. Transverse diffusivity refers to the diffusion across fibers rather than along the fibers and is believed to be a specific marker for axonal loss and demyelination associated with MS. No significant association between DTI-measures and PASAT performance was found and this negative finding was mainly attributed to psychometric qualities. These results indicate that diffusivity along the non-principal diffusion direction, a possible signature of MS-related white matter pathology, contributes to information processing speed as measured with the SDMT, a task that requires close visual tracking and a widely used clinical marker for cognitive decline in MS.

[Cognitive impairment]

Cognitive impairment is common in multiple sclerosis (MS), occurring at all stages of the disease, even at the earliest, and can be a major source of disability, social impairment, and impoverished quality of life. Cognitive dysfunction is mainly focused on working memory, conceptual reasoning, verbal fluency, speed of information processing, attention and executive function. Measures of information-processing speed appear to be the most robust and sensitive markers of cognitive impairment in MS patients. Cognitive testing in MS patients is complex and cognitive screening tests are time- and cost-saving test instruments. A comprehensive and sensitive cognitive test procedure should be administered to detect cognitive dysfunction, and recent studies demonstrate that single, predominantly speed-related cognitive tests may be superior to extensive and time-consuming test batteries in screening cognitive decline. Additional clinical factors, including disease course, fatigue, and affective disturbance, can impact the degree of MS-related cognitive impairment. Despite weak correlation with disease duration and physical disability status, the degree of cognitive impairment in MS has been related to the extent of topographically specific neuronal tissue damage and loss. Numerous studies have applied conventional and quantitative magnetic resonance imaging (MRI) techniques to correlate the profile and degree of cognitive impairment with various MRI-detectable abnormalities. The burden of MRI-visible lesions does not fully account for the degree of MS-related cognitive impairment. Nonconventional MRI findings suggest the extent of subtle tissue damage in normal-appearing white and grey matter to correlate best with the severity of cognitive impairment in MS patients. Structural MRI approaches have recently been extended by functional MRI studies scrutinizing the brain's ability for adaptive functional reorganization in the presence of widespread tissue damage. Cognitive impairment in MS seems to be not simply the result of tissue destruction, but also a balance between tissue destruction, tissue repair, and adaptive functional reorganization. These findings highlight the need to screen for cognitive deficits in MS patients to conduct potential cognitive rehabilitation intervention.

Cognitive impairments in relapsing-remitting multiple sclerosis: a meta-analysis

There is debate in the literature regarding the magnitude, nature, and influence of cognitive impairment in individuals with relapsing-remitting multiple sclerosis (RRMS). Therefore, we conducted a meta-analysis that quantified the overall magnitude of cognitive impairment in individuals with RRMS and identified the domains of cognition and clinical/demographic variables that were moderators of the overall effect. We included 57 studies with 3891 participants that yielded a total of 755 effect sizes. Overall, there was a moderate decline in cognitive functioning in individuals with RRMS compared with healthy controls. Larger effects were observed in cognitive domains of motor functioning, mood status and memory and learning. Regarding demographic and clinical variables, age and gender were moderators of cognitive impairment in all cognitive domains, whereas neurological disability and disease duration primarily moderated performance on tasks assessing memory and learning.

The reliability of the MSFC and its components

BACKGROUND

The Multiple Sclerosis Functional Composite (MSFC) is a multidimensional measurement tool for multiple sclerosis (MS) including a measure of ambulation (Timed 25-foot Walk [TWT]), arm function (Nine-Hole Peg Test [9HPT]) and cognition (Paced Auditory Serial Addition Test [PASAT]).

OBJECTIVES

To assess the reliability and practice effects in the Finnish version of the MSFC and its components.

MATERIALS AND METHODS

Ten relapsing-remitting MS patients and 10 healthy controls underwent five testing sessions with the MSFC over a 4-week period.

RESULTS

The MSFC showed excellent intra- (0.99) and inter-rater (1.0) reliability. The MSFC, especially the 9HPT and the PASAT showed significant practice effects. On the 9HPT the controls remained stable whereas the patients improved their performance; on the PASAT both groups improved.

CONCLUSIONS

The MSFC showed excellent intra- and inter-rater reliability although the 9HPT and the PASAT were prone to considerable practice effects.

Within-session practice effect on paced auditory serial addition test in multiple sclerosis

The paced auditory serial addition test (PASAT) is increasingly used in multiple sclerosis (MS) studies. Since these studies rely on repeated assessments with relatively short inter-test intervals, practice effects can be a confounding factor. We examined intra-session PASAT practice effects in 70 relapsing remitting (RR) and 40 secondary progressive (SP) patients. The average number of correct answers increased from 39.6 ± 11.7 in the first PASAT run to 43.8 ± 11.4 in the second run for the RR group, and from 39.1 ± 11.6 to 41.8 ± 13.3 in the SP group. PASAT scores showed a consistent decrease when comparing the second half of each test to the first half for both patient groups, and for both runs. Items for which the answer was a number greater than 9 had the same discrimination ability as other test items, but were significantly more difficult. A simulation of `single-button' responses supported the use of the simplified scoring method which is currently used in fMRI studies. Our results demonstrate a within-session PASAT practice effect in MS, as well as a fatigability effect for both patient groups.

One-year follow-up study of relapsing-remitting MS patients' cognitive performances: Paced Auditory Serial Addition Test's susceptibility to change

To evaluate the progression of cognitive decline in multiple sclerosis (MS) patients and the susceptibility of the Multiple Sclerosis Functional Composite (MSFC) Paced Auditory Serial Addition Test (PASAT) to change, we conducted a 1-year follow-up with a comprehensive neuropsychological examination to 19 initially cognitively impaired and 26 cognitively intact relapsing-remitting MS patients, and to 48 healthy controls. The results indicated that the cognitive performance of MS patients remained relatively stable. Healthy controls tended to perform better on most neuropsychological measures at follow-up, the same was not observed in the MS groups. PASAT showed a significant difference between the groups: the cognitively impaired group tended to deteriorate, whereas the control group and the cognitively intact group improved. The change in PASAT could not be explained by the background variables, for example, mood, quality of life, or nervousness. Therefore, the MSFC-PASAT seems to be a sensitive measure to show clinical change in the cognitive status.

A shortened version of PASAT-3 is feasible

The Paced Auditory Serial Addition Test (PASAT), most used neuropsychological test in people with multiple sclerosis (pwMS), is available as PASAT-3 and more difficult PASAT-2. We determined PASAT performance in 105 pwMS and 105 matched controls and assessed the utility of a shortened PASAT-3 version. Qualitative and quantitative analyses were performed, the latter involving assessment of dyads (two consecutive correct responses) and singles (correct response between two omitted responses). Based on provisional results we then calculated the sensitivity of the first 20 items of PASAT-3 in relation to the full version. Mean PASAT-2 and 3 total score, dyads and singles differed significantly (P < or = 0.0002) in pwMS and controls, due to more omissions in pwMS, number and type of incorrect answers did not differ. Differences between pwMS and controls were highly significant for the first 50, 40, 30 and 20 responses of the PASAT-3. The sensitivity of the first 20 items of PASAT-3 was 87% (95% CI 0.70-1.00). PASAT-3 and PASAT-2 effectively discriminate pwMS from controls. Use of the first 20 items of PASAT-3 appears as a highly useful PASAT-3 version as it retains the discriminative value and sensitivity of the full version yet is quicker to administer and less demanding.

Cognitive and neurophysiological outcome of cardiac arrest survivors treated with therapeutic hypothermia

BACKGROUND AND PURPOSE

Cognitive deficits are common in survivors of cardiac arrest (CA). The aim of this study was to examine the effect of therapeutic hypothermia after CA on cognitive functioning and neurophysiological outcome.

METHODS

A cohort of 70 consecutive adult patients resuscitated from out-of-hospital ventricular fibrillation CA were randomly assigned to therapeutic hypothermia of 33 degrees C for 24 hours accomplished by external cooling or normothermia. Neuropsychological examination was performed to 45 of the 47 conscious survivors of CA (27 in hypothermia and 18 in normothermia group) 3 months after the incident. Quantitative electroencephalography (Q-EEG) and auditory P300 event-related potentials were studied on 42 patients at the same time point.

RESULTS

There were no differences between the 2 treatment groups in demographic variables, depression, or delays related to the resuscitation. No differences were found in any of the cognitive functions between the 2 groups. 67% of patients in hypothermia and 44% patients in normothermia group were cognitively intact or had only very mild impairment. Severe cognitive deficits were found in 15% and 28% of patients, respectively. All Q-EEG parameters were better in the hypothermia-treated group, but the differences did not reach statistical significance. The amplitude of P300 potential was significantly higher in hypothermia-treated group.

CONCLUSIONS

The use of therapeutic hypothermia was not associated with cognitive decline or neurophysiological deficits after out-of-hospital CA.

Cognitive impairment in multiple sclerosis

PURPOSE OF REVIEW

For a long time, cognitive impairment in multiple sclerosis patients has been considered less important than, for instance, physical disability. This is no longer true because of the crucial role that cognitive deficits play in the good day-to-day adjustment of patients. This review highlights recent progress made in this area. A special focus lies on studies investigating the neural correlates of cognitive impairment in multiple sclerosis patients as detectable by conventional, quantitative and functional magnetic resonance imaging.

RECENT FINDINGS

Measures of information-processing speed appear to be the most robust and sensitive markers of cognitive impairment in multiple sclerosis patients. Recent studies demonstrate that single, predominantly speed-related cognitive tests may be superior to extensive and time-consuming test batteries in screening overall cognitive decline. Quantitative magnetic-resonance-imaging findings suggest the extent of subtle tissue damage in normal-appearing white and grey matter to correlate best with the severity of cognitive impairment in multiple sclerosis patients.

SUMMARY

From neuropsychological test data, and findings from magnetic resonance imaging and functional magnetic resonance imaging it is evident that cognitive impairment in multiple sclerosis is not just the result of tissue destruction, but rather a balance between tissue destruction, tissue repair, and adaptive functional reorganization.