Isolated cognitive impairment in people with multiple sclerosis: frequency, MRI patterns and its development over time

OBJECTIVES

To study the frequency of isolated (i.e., single-domain) cognitive impairments, domain specific MRI correlates, and its longitudinal development in people with multiple sclerosis (PwMS).

METHODS

348 PwMS (mean age 48 ± 11 years, 67% female, 244RR/52SP/38PP) underwent neuropsychological testing (extended BRB-N) at baseline and at five-year follow-up. At baseline, structural MRI was acquired. Isolated cognitive impairment was defined as a Z-score of at least 1.5 SD below normative data in one domain only (processing speed, memory, executive functioning/working memory, and attention). Multi-domain cognitive impairment was defined as being affected in ≥ 2 domains, and cognitively preserved otherwise. For PwMS with isolated cognitive impairment, MRI correlates were explored using linear regression. Development of isolated cognitive impairment over time was evaluated based on reliable change index.

RESULTS

At baseline, 108 (31%) PwMS displayed isolated cognitive impairment, 148 (43%) PwMS displayed multi-domain cognitive impairment. Most PwMS with isolated cognitive impairment were impaired on executive functioning/working memory (EF/WM; N = 37), followed by processing speed (IPS; N = 25), memory (N = 23), and attention (N = 23). Isolated IPS impairment was explained by a model of cortical volume and fractional anisotropy (adj. R2 = 0.539, p < 0.001); memory by a model with cortical volume and hippocampal volume (adj. R2 = 0.493, p = 0.002); EF/WM and attention were not associated with any MRI measure. At follow-up, cognitive decline was present in 11/16 (69%) of PwMS with isolated IPS impairment at baseline. This percentage varied between 18 and 31% of PwMS with isolated cognitive impairment in domains other than IPS at baseline.

CONCLUSION

Isolated cognitive impairment is frequently present in PwMS and can serve as a proxy for further decline, particularly when it concerns processing speed. Cortical and deep grey matter atrophy seem to play a pivotal role in isolated cognitive impairment. Timely detection and patient-tailored intervention, predominantly for IPS, may help to postpone further cognitive decline.

Cognitive rehabilitation and mindfulness reduce cognitive complaints in multiple sclerosis (REMIND-MS): A randomized controlled trial

BACKGROUND

Cognitive problems, both complaints and objective impairments, are frequent and disabling in patients with multiple sclerosis (MS) and profoundly affect daily living. However, intervention studies that focus on cognitive problems that patients experience in their daily lives are limited. This study therefore aimed to investigate the effectiveness of cognitive rehabilitation therapy (CRT) and mindfulness-based cognitive therapy (MBCT) on patient-reported cognitive complaints in MS.

METHODS

In this randomized-controlled trial, MS patients with cognitive complaints completed questionnaires and underwent neuropsychological assessments at baseline, post-treatment and 6-month follow-up. Patient-reported cognitive complaints were primarily investigated. Secondary outcomes included personalized cognitive goals and objective cognitive function. CRT and MBCT were compared to enhanced treatment as usual (ETAU) using linear mixed models.

RESULTS

Patients were randomized into CRT (n = 37), MBCT (n = 36) or ETAU (n = 37), of whom 100 completed the study. Both CRT and MBCT positively affected patient-reported cognitive complaints compared to ETAU at post-treatment (p<.05), but not 6 months later. At 6-month follow-up, CRT had a positive effect on personalized cognitive goals (p=.028) and MBCT on processing speed (p=.027). Patients with less cognitive complaints at baseline benefited more from CRT on the Cognitive Failures Questionnaire (i.e. primary outcome measuring cognitive complaints) at post-treatment (p=.012-.040), and those with better processing speed at baseline benefited more from MBCT (p=.016).

CONCLUSION

Both CRT and MBCT alleviated cognitive complaints in MS patients immediately after treatment completion, but these benefits did not persist. In the long term, CRT showed benefits on personalized cognitive goals and MBCT on processing speed. These results thereby provide insight in the specific contributions of available cognitive treatments for MS patients.

Cognitive performance in multiple sclerosis: what is the role of the gamma-aminobutyric acid system?

Cognitive impairment occurs in 40-65% of persons with multiple sclerosis and may be related to alterations in glutamatergic and GABAergic neurotransmission. Therefore, the aim of this study was to determine how glutamatergic and GABAergic changes relate to cognitive functioning in multiple sclerosis in vivo. Sixty persons with multiple sclerosis (mean age 45.5 ± 9.6 years, 48 females, 51 relapsing-remitting multiple sclerosis) and 22 age-matched healthy controls (45.6 ± 22.0 years, 17 females) underwent neuropsychological testing and MRI. Persons with multiple sclerosis were classified as cognitively impaired when scoring at least 1.5 standard deviations below normative scores on ≥30% of tests. Glutamate and GABA concentrations were determined in the right hippocampus and bilateral thalamus using magnetic resonance spectroscopy. GABA-receptor density was assessed using quantitative [¹¹C]flumazenil positron emission tomography in a subset of participants. Positron emission tomography outcome measures were the influx rate constant (a measure predominantly reflecting perfusion) and volume of distribution, which is a measure of GABA-receptor density. Twenty persons with multiple sclerosis (33%) fulfilled the criteria for cognitive impairment. No differences were observed in glutamate or GABA concentrations between persons with multiple sclerosis and healthy controls, or between cognitively preserved, impaired and healthy control groups. Twenty-two persons with multiple sclerosis (12 cognitively preserved and 10 impaired) and 10 healthy controls successfully underwent [¹¹C]flumazenil positron emission tomography. Persons with multiple sclerosis showed a lower influx rate constant in the thalamus, indicating lower perfusion. For the volume of distribution, persons with multiple sclerosis showed higher values than controls in deep grey matter, reflecting increased GABA-receptor density. When comparing cognitively impaired and preserved patients to controls, the preserved group showed a significantly higher volume of distribution in cortical and deep grey matter and hippocampus. Positive correlations were observed between both positron emission tomography measures and information processing speed in the multiple sclerosis group only. Whereas concentrations of glutamate and GABA did not differ between multiple sclerosis and control nor between cognitively impaired, preserved and control groups, increased GABA-receptor density was observed in preserved persons with multiple sclerosis that was not seen in cognitively impaired patients. In addition, GABA-receptor density correlated to cognition, in particular with information processing speed. This could indicate that GABA-receptor density is upregulated in the cognitively preserved phase of multiple sclerosis as a means to regulate neurotransmission and potentially preserve cognitive functioning.

Episodic Past, Future, and counterfactual thinking in Relapsing-Remitting Multiple sclerosis

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Performance in episodic past, future or counterfactual thinking in relapsing-remitting MS and controls was explored.

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Behavioral and diffusion weighted imaging were used to evaluate associations between white matter integrity and group differences in performance.

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Relative to controls, MS patients showed reductions in episodic details across all three simulations.

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Reduced white matter integrity in three association tracts predicted this reduction in episodic details during counterfactual simulations.

Multiple sclerosis (MS) is a progressive disease characterized by widespread white matter lesions in the brain and spinal cord. In addition to well-characterized motor deficits, MS results in cognitive impairments in several domains, notably in episodic autobiographical memory. Recent studies have also revealed that patients with MS exhibit deficits in episodic future thinking, i.e., our capacity to imagine possible events that may occur in our personal future. Both episodic memory and episodic future thinking have been shown to share cognitive and neural mechanisms with a related kind of hypothetical simulation known as episodic counterfactual thinking: our capacity to imagine alternative ways in which past personal events could have occurred but did not. However, the extent to which episodic counterfactual thinking is affected in MS is still unknown. The current study sought to explore this issue by comparing performance in mental simulation tasks involving either past, future or counterfactual thoughts in relapsing-remitting MS. Diffusion weighted imaging (DWI) measures were also extracted to determine whether changes in structural pathways connecting the brain’s default mode network (DMN) would be associated with group differences in task performance. Relative to controls, patients showed marked reductions in the number of internal details across all mental simulations, but no differences in the number of external and semantic-based details. It was also found that, relative to controls, patients with relapsing-remitting MS reported reduced composition ratings for episodic simulations depicting counterfactual events, but not so for actual past or possible future episodes. Additionally, three DWI measures of white matter integrity—fractional anisotropy, radial diffusivity and streamline counts—showed reliable differences between patients with relapsing-remitting MS and matched healthy controls. Importantly, DWI measures associated with reduced white matter integrity in three association tracts on the DMN—the right superior longitudinal fasciculus, the left hippocampal portion of the cingulum and the left inferior longitudinal fasciculus—predicted reductions in the number of internal details during episodic counterfactual simulations. Taken together, these results help to illuminate impairments in episodic simulation in relapsing-remitting MS and show, for the first time, a differential association between white matter integrity and deficits in episodic counterfactual thinking in individuals with relapsing-remitting MS.

Brief international cognitive assessment for multiple sclerosis (BICAMS) cut-off scores for detecting cognitive impairment in multiple sclerosis

BACKGROUND

Cognitive impairment (CI) affects 35-65% of multiple sclerosis (MS) patients. The Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) has been proposed as a highly feasible and cost-effective tool for cognitive impairment (CI) screening in MS. The tool yields scores that should, ideally, readily convey patients' cognitive status to the clinicians.

METHODS

To this aim, this study sought for cut-off scores of the three BICAMS test in a sample of 960 MS patients. We used three definitions for CI: 1.5, 1,65 and 2 standard deviations below the mean. Receiver operating characteristic (ROC) statistics helped us determine the capacity of BICAMS to diagnose CI. Optimal cut-offs were determined by the delta distance. Positive and negative predictive values, along with overall accuracy were also calculated.

RESULTS

Symbol Digit Modalities Test (SDMT) and California Verbal Learning Test-II (CVLT-II) showed a diagnostic accuracy ranging from 74.6 to 77.4%, across the three CI definitions. The accuracy of Brief Visuospatial Memory Test-Revised (BVMT-R) was over 88%. SDMT had a balanced sensitivity, while CVLT-II and BVMT-R had higher specificities than sensitivities at detecting CI. More specifically, BVMT-R showed 100% specificity for all CI definitions. Raw cut-off scores for BICAMS tests are also provided within the manuscript, along with the diagnostic calculations.

CONCLUSIONS

In this study, we confirmed that BICAMS is a good screening tool for CI and that simple cut-offs can be used in the everyday neurological practice.

Validation of the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) in a Colombian Population

BACKGROUND

Cognitive impairment has been recognized as an important factor in multiple sclerosis (MS) in the past few years. One brief, reliable and valid tool to assess cognition in MS is the BICAMS, which encompasses the Symbol Digit Modalities Test (SDMT), the California Verbal Learning Test (CVLT II), and the Brief Visuospatial Memory Test - Revised (BVMT-R). Continuing with the international initiative to validate the BICAMS in different countries, here we present the results obtained from the efforts in validating such test in the Colombian population.

METHOD

100 healthy controls and 50 MS patients participated in the study, group matched for age, education and gender. Subjects completed all three tests of the BICAMS. Instead of the CVLT-II, the Colombian validated form PAMCL (Prueba de Aprendizaje y Memoria con Codificación Libre) was used. Test-retest measures were obtained for 16 patients in order to test for reliability.

RESULTS

Evidence of criterion validity was obtained, MS group performing significantly worse than HC group in all three tests (SDMT: p= .001, d= 0.59; PAMCL: p= .03, d= 0.38; BVMT-R: p<.001, d= 0.58). Test-retest was also obtained, finding significant correlations for all three tests (SDMT: r=0.932, p<.00; BVMT-R: r=0.863, p<.001; PAMCL: r=0.889, p<.001). Standardization of raw scores to uncontrolled scaled scores was done and these scores were then adjusted for age and years of schooling using a multiple linear regression.

CONCLUSIONS

The BICAMS proved to be a valid and sensitive tool to screen for cognitive impairment in MS patients.

Verbal fluency deficits in clinically isolated syndrome suggestive of multiple sclerosis

BACKGROUND

Little is known about relationships between Cognitive Impairment (CI) and verbal fluency measures in patients with a Clinically Isolated Syndrome (CIS) suggestive of Multiple Sclerosis. The aim of this study was to assess the extent of verbal fluency deficits and their predictive value for the presence of a CI in a population of CIS patients.

METHODS

CI was detected by the Rao's Brief Repeatable Battery (BRB) and the Stroop Test (ST) in 100 CIS patients. The BRB includes the Word List Generation (WLG) test for semantic verbal fluency. The FAS test was used to investigate phonemic verbal fluency. CI was defined as the failure in at least 3 tests on BRB (without WLG to exclude criterion contamination bias) and ST.

RESULTS

Eleven patients failed in at least 3 of the BRB tests and were classified as cognitively impaired. The comparison of Receiver Operating Characteristic curves showed that the Area Under the Curve (AUC) of the WLG was not significantly different from the AUC of the FAS (0.787 vs 0.755; p=N.S.). A cut-off <17 words for the WLG achieved 64% of sensitivity and a 79% of specificity, and a cut-off <28 words achieved 82% of sensitivity and a 66% of specificity in discriminating patients with CI.

CONCLUSIONS

Verbal fluency deficits occur early in the disease course and may predict the presence of CI in CIS patients.

Multicenter randomized clinical trial of donepezil for memory impairment in multiple sclerosis

OBJECTIVES

The goal of this study was to determine if memory would be improved by donepezil as compared to placebo in a multicenter, double-blind, randomized clinical trial (RCT).

METHODS

Donepezil 10 mg daily was compared to placebo to treat memory impairment. Eligibility criteria included the following: age 18-59 years, clinically definite multiple sclerosis (MS), and performance ≤ ½ SD below published norms on the Rey Auditory Verbal Learning Test (RAVLT). Neuropsychological assessments were performed at baseline and 24 weeks. Primary outcomes were change on the Selective Reminding Test (SRT) of verbal memory and the participant's impression of memory change. Secondary outcomes included changes on other neuropsychological tests and the evaluating clinician's impression of memory change.

RESULTS

A total of 120 participants were enrolled and randomized to either donepezil or placebo. No significant treatment effects were found between groups on either primary outcome of memory or any secondary cognitive outcomes. A trend was noted for the clinician's impression of memory change in favor of donepezil (37.7%) vs placebo (23.7%) (p = 0.097). No serious or unanticipated adverse events attributed to study medication developed.

CONCLUSIONS

Donepezil did not improve memory as compared to placebo on either of the primary outcomes in this study.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence which does not support the hypothesis that 10 mg of donepezil daily for 24 weeks is superior to placebo in improving cognition as measured by the SRT in people with MS whose baseline RAVLT score was 0.5 SD or more below average.

Diffusion tensor imaging abnormalities in cognitively impaired multiple sclerosis patients

BACKGROUND

Cognitive impairment can add to the burden of disease in patients with multiple sclerosis (MS). The aim of this study was to assess the relative importance of diffusion tensor imaging (DTI) indices derived from normal appearing white matter (NAWM) and grey matter (NAGM) in determining cognitive dysfunction in MS patients.

METHODS

Sixty two MS patients [51 female, mean age = 41 (sd = 9.6) years, median expanded disability status scale (EDSS) = 2.5] meeting modified McDonald criteria for MS underwent neuropsychological testing using the Neuropsychological Screening Battery for MS (NSBMS) and magnetic resonance imaging (MRI, 1.5T GE) that included DTI sequences. Total T1 hypointense and T2 hyperintense lesion volumes were obtained using semi-automated software. Lesion volumes were subtracted from whole-brain parenchyma to obtain measures of NAWM and NAGM. Fractional anisotropy (FA) of NAWM and mean diffusivity (MD) of NAGM were obtained.

RESULTS

Cognitive impairment was present in 11 patients (18%). These patients had higher EDSS scores, were less educated, and were more likely to have secondary progressive MS. They also had higher hypointense (p = 0.001) and hyperintense (p = 0.004) lesion volumes, greater NAWM atrophy (p = 0.007), lower FA of total NAWM (p = 0.003), and higher MD of total NAGM (p = 0.015). Using a logistic regression analysis, and after controlling for demographic and disease-related differences between groups, FA of NAWM emerged as a significant predictor of cognitive impairment adding to the variance derived from lesion and atrophy data.

CONCLUSION

This study underlies the important role of normal-appearing brain tissue in the pathogenesis of MS-related cognitive impairment.

APOE epsilon4 and the cognitive genetics of multiple sclerosis

BACKGROUND

Evidence linking APOE to myelin repair, neuronal plasticity, and cerebral inflammatory processes suggests that it may be relevant in multiple sclerosis (MS). The purpose of this study was to determine whether the epsilon4 allele of APOE is associated with cognitive deficits in patients with MS.

METHOD

Using a case-control design, 50 patients with MS with the epsilon4 allele (epsilon4+) and 50 epsilon4-negative (epsilon4-) patients with MS were tested using a comprehensive battery of tests evaluating the cognitive domains most often affected in MS.

RESULTS

The epsilon4+ and epsilon4- patients with MS were well-matched with respect to demographic variables (age, gender, ethnicity, education, employment status, premorbid IQ) and disease variables (disease course, disease duration, Expanded Disability Status Scale, 25-foot timed walk, 9-hole pegboard test). In addition, the groups were similar in depressive symptoms, in the proportion of patients receiving disease-modifying therapy, and in carriage of the APOE epsilon2 allele. Results showed that none of the 11 cognitive outcome variables differed between epsilon4+ and epsilon4- patients with MS. Cognitive measures were also unrelated to epsilon4 interactions with age and gender. The incidence of overall cognitive dysfunction did not differ between epsilon4+ and epsilon4- groups, nor did failure on any test, and epsilon4 carriage was not a significant predictor of any adverse cognitive outcome. These negative results endured with the exclusion of epsilon2+ subjects from the analyses.

CONCLUSION

This study does not support a role for the epsilon4 allele in cognitive dysfunction in multiple sclerosis.