The impact of disease modifying therapies on cognitive functions typically impaired in multiple sclerosis patients: a clinician's review

Dementia in People With Multiple Sclerosis: A Systematic Review and Meta-Analysis

INTRODUCTION

Multiple sclerosis (MS), as an autoimmune demyelinating disorder, is associated with cognitive dysfunction. Dementia can result from severe cognitive dysfunction or other pathways in MS, but the exact mechanisms and prevalence are unknown.

OBJECTIVE

This review aimed to determine the pooled prevalence and risk of dementia in people with MS (PwMS).

DESIGN

This meta-analysis was performed in accordance with the guidelines established by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA).

METHODS

Embase, PubMed, Web of Science, and Scopus were comprehensively searched up to August 29, 2024, to identify observational studies that examined the prevalence or hazard ratio (HR) of dementia among PwMS. This meta-analysis used a random-effects model to calculate the pooled prevalence and risk of dementia among PwMS, where the prevalence rate and HR were the main metrics for effect size.

RESULTS

Ten studies, including a total of 37,831 PwMS, estimated the prevalence of dementia in PwMS to be 5.31% (I2 = 99.2%, 95% CI: 2.25%-11.98%). In addition, a meta-analysis of four studies assessed the HR of dementia among PwMS, revealing a pooled HR of 1.67 (p < 0.01, I2 = 73.5%, 95% CI: 1.31-2.13).

CONCLUSION

While dementia is not a common feature of MS, PwMS still have a significantly higher risk of developing it, compared to healthy indiviuals. However, the considerable variability across studies indicates that these estimates should be interpreted with caution, as inconsistencies in research approaches may have influenced the results. These findings warrant further validation.

Motor symptoms at onset and manual dexterity predict cognitive impairment in drug-naïve individuals with multiple sclerosis

BACKGROUND

Even in the early stages, cognitive impairment (CI) is commonly seen in multiple sclerosis (MS) patients. The current study set out to estimate the frequency and contributing factors for developing CI among a large group of drug-naïve MS patients.

METHODS

42 healthy controls matched for age, sex, and education were included in the study, along with 140 drug-naïve MS patients who were diagnosed using the 2017 McDonald criteria for MS. Patient data included complete clinical and demographic information and clinical scales including, Expanded Disability Status Scale (EDSS), 9-Hole Peg test (9-HPT), Brief International Cognitive Assessment Scale of MS (BICAMS) and serum level light chain (sNFL) were assessed at the initial visit following diagnosis.

RESULTS

Among MS patients who had never taken medication, CI was noticeably high (27.14 %). In comparison to other clinical phenotypes among drug-naïve MS patients, the SPMS had the highest incidence of CI (55.56 %) and the lowest among CIS (11.76 %). First motor presentation and low years of education were significantly linked to CI (0.026, and 0.008 respectively). Patients with CI had significantly higher EDSS (P = 0.012) and 9-HPT scores (P = 0.006) compared with non-CI patients. Additionally, sNFL was significantly higher in CI than non-CI group (P = 0.026). 9-HPT and motor presentation at onset were the only independent contributing factors of CI in multivariate regression analysis with CI.

CONCLUSION

The current study demonstrates that a significant portion of MS patients who are drug-naïve have CI. Motor symptoms at onset and 9-HPT performance were identified as independent contributing factors of CI. Elevated serum NFL levels reflect associated neuroaxonal damage rather than being a direct contribution.

TRIAL REGISTRATION

Clinicaltrial.gov registry number NCT06197841.

Cognitive changes in patients with relapse-free MS treated with high efficacy therapies: the predictive value of paramagnetic rim lesions

BACKGROUND

High-efficacy disease-modifying therapies (HETs) have substantially improved multiple sclerosis (MS) management, yet ongoing cognitive decline remains a concern. This study aims to assess Symbol Digit Modalities Test (SDMT) changes in patients with stable relapsing-remitting MS (RRMS) treated with HETs and to evaluate the role of baseline MRI biomarkers as predictors of SDMT changes.

METHODS

Consecutive patients with RRMS treated with HETs underwent clinical, SDMT and MRI assessment at baseline with SDMT and clinical re-evaluation after 24 months. Patients presenting relapses or MRI activity (new T2 and/or gadolinium-enhancing lesions) during follow-up were excluded. Cognitive changes were defined using the 90% CI regression-based reliable change index methodology accounting for sex, age, education and baseline score. Baseline MRI examination included three-dimensional-sagittal Fluid Attenuated Inversion Recovery (FLAIR), T1-Magnetization Prepared - RApid Gradient Echo (T1-MPRAGE) and quantitative susceptibility mapping (QSM) for paramagnetic rim lesions (PRLs) and QSM-isointense lesions (ISO) assessment. Univariate and multivariable regression analyses were performed to predict SDMT changes.

RESULTS

90 patients (mean age: 40.3 years, median Expanded Disability Status Scale: 2.0) were included. PRLs were present in 46 (51.1%) patients. After 24 months, 13 (14.4%) patients showed SDMT decline and 8 (8.9%) showed improvement. At multivariable analyses, PRLs were associated with higher risk of SDMT decline (β: 2.70, p: 0.02, OR: 14.82) while higher ISO lesion volumes were weakly associated with SDMT improvement (β: 0.07, p: 0.01, OR: 1.07).

CONCLUSIONS

SDMT decline and improvement are detectable in patients with RRMS without clinical or MRI activity over 2 years. PRLs seem to predict SDMT decline in MS, underscoring the critical role of compartmentalised chronic inflammation in disease progression.

Investigation of comparative nonword repetition performance in multiple sclerosis: Group differences, subtype variations, and disability effects

This study investigated Nonword Repetition (NWR) tasks in individuals with Multiple Sclerosis (MS) compared to healthy controls (HC), focusing on phonological working memory (WMP). Significant differences were found in NWR acurracy (NWRacc) score between MS subgroups and HC (H = 48.2, p < 0.001). NWRacc decreased as the number of syllables increased in both groups, indicating increased cognitive load. All MS subtypes showed lower NWRacc compared to HC across varying syllable lengths (Mann Whitney U Test: two syllables U = 64.5, p < 0.001; three syllables U = 183, p < 0.001; four syllables U = 248, p < 0.001; five syllables U = 283.5, p < 0.001). However, no significant differences were found within MS subtypes based on syllable length. NWRacc did not differ between mild and severe MS groups. Overall, the NWR test effectively assessed WMP in MS, highlighting its utility in diagnosing and addressing language-cognitive challenges in individuals with MS. This underscores the importance of tailored intervention strategies to mitigate these challenges.

Cognitive impairment in multiple sclerosis: from phenomenology to neurobiological mechanisms

Multiple sclerosis (MS) is an autoimmune-mediated disease of the central nervous system characterized by inflammation, demyelination and chronic progressive neurodegeneration. Among its broad and unpredictable range of clinical symptoms, cognitive impairment (CI) is a common and disabling feature greatly affecting the patients' quality of life. Its prevalence is 20% up to 88% with a wide variety depending on the phenotype of MS, with highest frequency and severity in primary progressive MS. Involving different cognitive domains, CI is often associated with depression and other neuropsychiatric symptoms, but usually not correlated with motor and other deficits, suggesting different pathophysiological mechanisms. While no specific neuropathological data for CI in MS are available, modern research has provided evidence that it arises from the disease-specific brain alterations. Multimodal neuroimaging, besides structural changes of cortical and deep subcortical gray and white matter, exhibited dysfunction of fronto-parietal, thalamo-hippocampal, default mode and cognition-related networks, disruption of inter-network connections and involvement of the γ-aminobutyric acid (GABA) system. This provided a conceptual framework to explain how aberrant pathophysiological processes, including oxidative stress, mitochondrial dysfunction, autoimmune reactions and disruption of essential signaling pathways predict/cause specific disorders of cognition. CI in MS is related to multi-regional patterns of cerebral disturbances, although its complex pathogenic mechanisms await further elucidation. This article, based on systematic analysis of PubMed, Google Scholar and Cochrane Library, reviews current epidemiological, clinical, neuroimaging and pathogenetic evidence that could aid early identification of CI in MS and inform about new therapeutic targets and strategies.