Cognitive skill learning in multiple sclerosis: A meaningful component of the neuropsychological profile

Cognitive skill learning (CSL) refers to the capacity to improve performance on specific cognitive operations through repeated practice. We hypothesized that high CSL aptitude may promote accumulation of cognitive reserve, and resiliency to cognitive decline, in people with Multiple Sclerosis (MS). Using an adaptive working memory training paradigm, we obtained CSL aptitude indices (amount of improvement on the training task over time) in MS patients for a single session of practice (25-30 min), and longer-term practice (twenty sessions). Neuropsychological performance was assessed with the Symbol Digit Modalities Test (SDMT), Paced Auditory Serial Addition Test (PASAT), and the Raven's Advanced Progressive Matrices (RAPM). CSL aptitude measures were positively correlated with neuropsychological performance, and had high diagnostic accuracy for classifying cognitive impairment in MS, defined as 1.5 SD below the demographics-corrected normative mean of the SDMT. Positive relationships between CSL aptitude measures and neuropsychological performance tended to be more pronounced for individuals with high estimated cognitive reserve, suggesting that high CSL aptitude is a a factor that promotes the protective effects of cognitive reserve. Furthermore, regression analyses indicated that CSL aptitude is separable from baseline cognitive capacity. The findings suggest that CSL aptitude impacts the neuropsychological profile in MS, and may be a factor underlying variance in cognitive resiliency.

Cognitive performance and cognitive workload in multiple sclerosis: Two different constructs of cognitive functioning?

BACKGROUND

Cognitive impairment in individuals with Multiple Sclerosis (iwMS) is traditionally diagnosed using performance measures on cognitive tests. Yet, performance on cognitive tests does not convey the amount of mental effort or cognitive workload it takes to complete the task. The main aim was to evaluate whether cognitive performance and cognitive workload are two different constructs of cognitive functioning in iwMS.

METHODS

IwMS were categorized into cognitive impairments (iwMS+, n = 10) and no cognitive impairments (iwMS-, n = 12) using their performance on Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS). Their scores on BICAMS, Stroop, and trail making tests were compared to age- and education-matched controls (n = 22). Cognitive workload was assessed using the self-reported NASA Task Load Index and the Index of Cognitive Activity, derived from pupillary response.

RESULTS

IwMS+ performed worse on most cognitive tests compared to iwMS- and controls. However, iwMS+ did not report or exhibit greater cognitive workload compared to the other groups. Potential confounding variables, such as sex, use of antidepressants, and symptoms of depression, fatigue, and dysautonomia did not influence the lack of correlation between cognitive performance and cognitive workload in all three groups.

CONCLUSION

Cognitive performance and cognitive workload seem to measure different cognitive constructs of cognitive functioning in MS. Our results suggest that iwMS+ do not show effective allocation of cognitive resources to compensate for deteriorated performance in cognitive tests.

Computerized neuropsychological assessment devices in multiple sclerosis: A systematic review

Background:

The proliferation of computerized neuropsychological assessment devices (CNADs) for screening and monitoring cognitive impairment is increasing exponentially. Previous reviews of computerized tests for multiple sclerosis (MS) were primarily qualitative and did not rigorously compare CNADs on psychometric properties.

Objective:

We aimed to systematically review the literature on the use of CNADs in MS and identify test batteries and single tests with good evidence for reliability and validity.

Method:

A search of four major online databases was conducted for publications related to computerized testing and MS. Test–retest reliability and validity coefficients and effect sizes were recorded for each CNAD test, along with administration characteristics.

Results:

We identified 11 batteries and 33 individual tests from 120 peer-reviewed articles meeting the inclusion criteria. CNADs with the strongest psychometric support include the CogState Brief Battery, Cognitive Drug Research Battery, NeuroTrax, CNS-Vital Signs, and computer-based administrations of the Symbol Digit Modalities Test.

Conclusion:

We identified several CNADs that are valid to screen for MS-related cognitive impairment, or to supplement full, conventional neuropsychological assessment. The necessity of testing with a technician, and in a controlled clinic/laboratory environment, remains uncertain.

Comparison of the abbreviated minimal assessment of cognitive function in multiple sclerosis (aMACFIMS) and the brief international cognitive assessment for multiple sclerosis (BICAMS)

BACKGROUND

Cognitive impairment is a prevalent and often intrusive problem among persons with multiple sclerosis (PwMS). Valid and reliable assessments, including quick screening measures, are crucial. The Brief International Cognitive Assessment for MS (BICAMS) was developed for this reason. While it lends itself to use in locations where formal neuropsychological resources might be limited, it does not include measures of verbal fluency or executive functioning, domains assessed as part of the Minimal Assessment of Cognitive Function in MS (MACFIMS).

OBJECTIVE

Given previous evidence that shortened MACFIMS measures have strong criterion validity, this study aimed to determine which of these should be included in the abbreviated MACFIMS (aMACFIMS), and how the aMACFIMS compares to the BICAMS.

METHODS

One hundred forty-seven PwMS were included in the analyses. A stepwise logistic regression was used to determine the measures in the aMACFIMS. Receiver-operating-characteristic (ROC) curves assessed the classification accuracy, sensitivity, and specificity. The batteries' sensitivity, specificity, and predictive values were then compared.

RESULTS

Compared to the BICAMS, the final aMACFIMS had higher specificity (87% versus 72%) and positive predictive value (86% versus 77%), but lower sensitivity (71% versus 81%).

CONCLUSION

The aMACFIMS has several benefits, including reduced administration time and the addition of a verbal fluency/executive functioning measure.

Brain connectivity and cognitive processing speed in multiple sclerosis: A systematic review

BACKGROUND

Processing speed (PS) decline is the most commonly observed cognitive deficit in people with multiple sclerosis (MS) resulting in a significant impact on quality of life. Despite its importance, knowledge of the underlying neural substrates is lacking.

OBJECTIVE

As MS is increasingly recognised as a disconnection syndrome, our aim was to carry out a systematic literature review to clarify the relationship between PS performance and MRI measures of structural and functional brain connectivity in people with MS.

SEARCH METHODS

A literature search was carried out on PubMed and Web of Science that included publications predating September 2017. Additional articles were added after inspection of the reference lists of all selected papers.

DATA EXTRACTION

All selected papers were categorised in three sections according to the MRI measures investigated, independently or both. Quality assessment was carried out using a customised set of criteria.

RESULTS

Thirty-two articles met the inclusion criteria and were included in the review. Microstructural integrity of the anterior corpus callosum and functional connectivity of frontal areas were more consistently found to correlate with PS performance, though high variability of findings was observed across studies. Several methodological flaws emerged from the reviewed literature.

CONCLUSIONS

Despite the observed trends, no definite conclusions can be drawn on the relationship between brain connectivity and PS decline in MS given the limitations of the current literature. Future investigations may benefit from theoretical and methodological advances to clarify how MS-related brain damage affects patients' cognition.

Symbol Digit Modalities Test adaptation for Magnetic Resonance Imaging environment: A systematic review and meta-analysis

BACKGROUND

The Symbol Digit Modalities Test (SDMT) is widely used for cognitive evaluation of information processing speed (IPS), required in many cognitive operations. Despite being unspecific for different neurological disorders, it is sensitive to assess impaired performance related to stroke, Parkinson's disease, traumatic brain injury, and multiple sclerosis. However, in addition to evaluate the presence and severity of IPS impairment, it is of interest to determine the localization and integration of brain regions responsible for the functions assessed by the SDMT.

OBJECTIVE

To review the studies that adapted the SDMT to the magnetic resonance environment and obtain the brain areas associated with the performance of the task in healthy subjects with a meta-analysis.

METHODOLOGY

A systematic review was performed using ten studies published between 1990 and 2017, and selected from four databases. All studies included participants of both genders and age between 18 and 50 years, used Functional Magnetic Resonance Imaging (fMRI) and SDMT adaptation and reported brain regions associated with the task. Six of them also reported the region coordinates in a standard space, so they were included in a meta-analysis. Activation Likelihood Estimation algorithm, with significance for p < 0.05 corrected for multiple comparisons, was used to identify areas that are robustly related to the performance of the SDMT.

RESULTS

The areas predominantly reported in the studies of our meta-analysis were regions of the frontoparietal attentional network and occipital cortex, as well as cuneus, precuneus, and cerebellum. Individually all regions that survived the statistical threshold are consistent with what is expected after reviewing prospective studies.

CONCLUSIONS

The present study allowed the identification of brain areas activated during the performance of the SDMT in healthy subjects, and therefore it will help understanding the differences in brain activation by this task in clinical populations. Moreover, it may guide future studies of therapeutic strategies and interventions in those populations.

Incidental learning from the coding subtest of the Repeatable Battery for the Assessment of Neuropsychological Status

Incidental learning (IL) measures provide complementary assessment data reflecting subconscious encoding of information using methods that differ from the procedures of many traditional memory tests. We examined the concurrent validity of an IL measure based on the coding subtest of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Participants included veterans referred for outpatient neuropsychological testing. Performance on the IL procedures correlated more strongly with memory indices than other indices on the RBANS. Patients with at least four correct responses very rarely had significant memory impairments. Thus, IL appears to contribute to the overall assessment of memory and requires little administration time.