A Retrospective Exploratory Analysis on Cardiovascular Risk and Cognitive Dysfunction in Multiple Sclerosis

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.

Serum lipids and cognitive outcomes in multiple sclerosis; a systematic review and meta-analysis

BACKGROUND

Cognitive impairment is highly prevalent in multiple sclerosis (MS) with poorly understood underlying mechanisms. Lipids are considered to be associated with MS progression through the inflammatory and oxidative stress pathways, brain atrophy, cellular signaling, and tissue physiology. In addition, serum lipids are proposed as a modifiable factor affecting the neuropsychiatric condition; therefore, this study aims to assess the association between serum lipid levels and cognitive outcomes in MS.

METHODS

This study was carried out following the PRISMA 2020 statement. A systematic search was conducted in PubMed, Scopus, Web of Science, and Embase in March 2023, and the Joanna Briggs Institute (JBI)'s critical appraisal tools were utilized for risk of bias (RoB) assessments in the included studies. The quantitative synthesis was performed with the comprehensive meta-analysis (CMA3) software.

RESULTS

Out of 508 screened records, 7 studies were eventually found to meet our inclusion criteria. In two studies, the course of MS in the sample of the study was only Relapsing-Remitting MS (RRMS), whereas the other five studies' sample was a combination of different phenotypes. Studies utilized different scales such as Minimal Assessment of Cognitive Function in MS (MACFIMS), Brief International Cognitive Assessment for MS (BICAMS), Montreal Cognitive Assessment (MoCA), Brief Repeatable Battery of Neuropsychological Tests (BRB-N) for cognitive evaluations. Dealing with possible confounders such as age, disease duration and level of disability was the most common possible source of bias in the included studies. One study revealed an inverse relationship between serum levels of apolipoproteins (including ApoA-I, ApoB, and ApoB/ApoA-I) and Symbol Digit Modalities Test (SDMT) scores. Also, a correlation between 24S-hydroxycholesterol (24OHC) serum concentrations and SDMT score was reported in one study. The association between serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL) and different aspects of cognitive function was reported in the studies; however, serum levels of high-density lipoprotein cholesterol (HDL) were not found to be associated. The quantitative synthesis revealed a significant correlation between TC and the MoCA scores (r =-0.238; 95 %CI: -0.366 to -0.100; p-value = 0.001); however, the correlation between TG levels and MoCA were not statistically significant (r:-0.070; 95 %CI: -0.209 to 0.072; p-value: 0.334). In addition, the mata-analyses were not associated with significant findings regarding the correlation between lipid profiles (including HDL, LDL, TG, and TC) and other cognitive assessment scales including SDMT, Brief Visuospatial Memory Test (BVMT), and California Verbal Learning Test (CVLT) (p-values>0.05).

DISCUSSION

Available evidence suggested a link between TC and LDL with cognitive outcomes of MS patients which was not evident in our quantitative synthesis. The limited number of studies, high RoB, different cognitive assessment scales and reporting methods, and the cross-sectional design of the included studies, were the main limitations that alleviate the clinical significance of the findings of this study and suggested further investigations on this topic.

FUNDING AND REGISTRATION

The research protocol was approved and supported by the Student Research Committee, Tabriz University of Medical Sciences (grant number: 71,909). This study is registered in the international prospective register of systematic reviews (PROSPERO ID: CRD42023441625).

Cardiovascular risk factors in secondary progressive multiple sclerosis: A cross-sectional analysis from the MS-STAT2 randomized controlled trial

BACKGROUND AND PURPOSE

There is increasing evidence that cardiovascular risk (CVR) contributes to disability progression in multiple sclerosis (MS). CVR is particularly prevalent in secondary progressive MS (SPMS) and can be quantified through validated composite CVR scores. The aim was to examine the cross-sectional relationships between excess modifiable CVR, whole and regional brain atrophy on magnetic resonance imaging, and disability in patients with SPMS.

METHODS

Participants had SPMS, and data were collected at enrolment into the MS-STAT2 trial. Composite CVR scores were calculated using the QRISK3 software. Prematurely achieved CVR due to modifiable risk factors was expressed as QRISK3 premature CVR, derived through reference to the normative QRISK3 dataset and expressed in years. Associations were determined with multiple linear regressions.

RESULTS

For the 218 participants, mean age was 54 years and median Expanded Disability Status Scale was 6.0. Each additional year of prematurely achieved CVR was associated with a 2.7 mL (beta coefficient; 95% confidence interval 0.8-4.7; p = 0.006) smaller normalized whole brain volume. The strongest relationship was seen for the cortical grey matter (beta coefficient 1.6 mL per year; 95% confidence interval 0.5-2.7; p = 0.003), and associations were also found with poorer verbal working memory performance. Body mass index demonstrated the strongest relationships with normalized brain volumes, whilst serum lipid ratios demonstrated strong relationships with verbal and visuospatial working memory performance.

CONCLUSIONS

Prematurely achieved CVR is associated with lower normalized brain volumes in SPMS. Future longitudinal analyses of this clinical trial dataset will be important to determine whether CVR predicts future disease worsening.

Vascular function and cognition in persons with multiple sclerosis: Preliminary examination

BACKGROUND

Cognitive dysfunction is one of the most common consequences of multiple sclerosis (MS). Recent studies have noted a high incidence of vascular comorbidity that might be associated with cognitive decline among persons with MS. However, there is a lack of evidence on vascular biomarkers (e.g., arterial stiffness indices) that are associated with cognition in MS. The current study characterized differences in vascular function between persons with MS and healthy controls, and examined the association between vascular and cognitive function in persons with MS compared with healthy controls.

RESULTS

The MS group had significantly worse cognitive performance and higher cfPWV than healthy controls. There were significant bivariate correlations between the Symbol Digit Modalities Test (SDMT) score with AIx75 (r_s = -0.45) and cfPWV (r_s = 0.30) in the MS sample, but not in healthy controls. Regression analyses further indicated a nonlinear association between cfPWV and the SDMT in the MS sample (p-values for β coefficients < 0.05; adjusted R² = 0.10). No significant associations were observed among other cognitive and vascular outcomes.

CONCLUSION

Our findings suggest significant associations between arterial stiffness and cognitive processing speed in MS. This preliminary examination provides initial, cross-sectional support for future population-based research on cognitive and vascular function in persons with MS. Such results may be clinically important for developing interventions that focus on regulating vascular dysfunction as an early treatment for preventing cognitive impairment in the MS population.

The comorbidity and cognition in multiple sclerosis (CCOMS) neuroimaging protocol: Study rationale, MRI acquisition, and minimal image processing pipelines

The Comorbidity and Cognition in Multiple Sclerosis (CCOMS) study represents a coordinated effort by a team of clinicians, neuropsychologists, and neuroimaging experts to investigate the neural basis of cognitive changes and their association with comorbidities among persons with multiple sclerosis (MS). The objectives are to determine the relationships among psychiatric (e.g., depression or anxiety) and vascular (e.g., diabetes, hypertension, etc.) comorbidities, cognitive performance, and MRI measures of brain structure and function, including changes over time. Because neuroimaging forms the basis for several investigations of specific neural correlates that will be reported in future publications, the goal of the current manuscript is to briefly review the CCOMS study design and baseline characteristics for participants enrolled in the three study cohorts (MS, psychiatric control, and healthy control), and provide a detailed description of the MRI hardware, neuroimaging acquisition parameters, and image processing pipelines for the volumetric, microstructural, functional, and perfusion MRI data.

Effects of Vascular Comorbidity on Cognition in Multiple Sclerosis Are Partially Mediated by Changes in Brain Structure

Objective

Vascular comorbidities are associated with reduced cognitive performance and with changes in brain structure in people with multiple sclerosis (MS). Understanding causal pathways is necessary to support the design of interventions to mitigate the impacts of comorbidities, and to monitor their effectiveness. We assessed the inter-relationships among vascular comorbidity, cognition and brain structure in people with MS.

Methods

Adults with neurologist-confirmed MS reported comorbidities, and underwent assessment of their blood pressure, HbA1c, and cognitive functioning (i.e., Symbol Digit Modalities Test, California Verbal Learning Test, Brief Visuospatial Memory Test-Revised, and verbal fluency). Test scores were converted to age-, sex-, and education-adjusted z-scores. Whole brain magnetic resonance imaging (MRI) was completed, from which measures of thalamic and hippocampal volumes, and mean diffusivity of gray matter and normal-appearing white matter were converted to age and sex-adjusted z-scores. Canonical correlation analysis was used to identify linear combinations of cognitive measures (cognitive variate) and MRI measures (MRI variate) that accounted for the most correlation between the cognitive and MRI measures. Regression analyses were used to test whether MRI measures mediated the relationships between the number of vascular comorbidities and cognition measures.

Results

Of 105 participants, most were women (84.8%) with a mean (SD) age of 51.8 (12.8) years and age of symptom onset of 29.4 (10.5) years. Vascular comorbidity was common, with 35.2% of participants reporting one, 15.2% reporting two, and 8.6% reporting three or more. Canonical correlation analysis of the cognitive and MRI variables identified one pair of variates (Pillai's trace = 0.45, p = 0.0035). The biggest contributors to the cognitive variate were the SDMT and CVLT-II, and to the MRI variate were gray matter MD and thalamic volume. The correlation between cognitive and MRI variates was 0.50; these variates were used in regression analyses. On regression analysis, vascular comorbidity was associated with the MRI variate, and with the cognitive variate. After adjusting for the MRI variate, vascular comorbidity was not associated with the cognitive variate.

Conclusion

Vascular comorbidity is associated with lower cognitive function in people with MS and this association is partially mediated via changes in brain macrostructure and microstructure.

Lower cerebral arterial blood flow is associated with greater serum neurofilament light chain levels in multiple sclerosis patients

BACKGROUND

Hypoperfusion, vascular pathology, and cardiovascular risk factors are associated with disease severity in multiple sclerosis (MS). We aimed to assess relationships between cerebral arterial blood flow (CABF) and serum neurofilament light chain (sNfL), as neuronal damage biomarker.

METHODS AND MATERIALS

Total CABF was measured in 137 patients (86 clinically isolated syndrome (CIS)/relapsing-remitting (RR) and 51 progressive MS (PMS)) and 48 healthy controls (HCs) using Doppler ultrasound. sNfL was quantitated using single molecule assay (Simoa). 3.0T MRI examination allowed quantification of T2 lesion and whole-brain volume (WBV). Multiple linear regression models determined the sNfL associated with CABF after correction for demographic and MRI-derived variables.

RESULTS

After adjustment for age, sex and BMI, total CABF remained statistically significant and model comparisons showed that CABF explained additional 2.6% of the sNfL variance (β=-0.167, p=0.044). CABF also remained significant in a step-wise regression model (β=0.18, p=0.034) upon the inclusion of T2 lesion burden and WBV effects. Patients in the lowest CABF quartile (CABF≤761mL/min) had significantly higher sNfL (34.6pg/mL versus 23.9pg/mL, adjusted-p=0.042) when compared to the highest quartile (CABF≥1130mL/min).

CONCLUSION

Lower CABF is associated with increased sNfL in MS patients, highlighting the relationship between cerebral hypoperfusion and axonal pathology.

Cerebrospinal fluid biomarkers and cognitive functions at multiple sclerosis diagnosis

Cognitive impairment (CI) is a frequent and disabling symptom in Multiple Sclerosis (MS). Axonal damage may contribute to CI development from early stages. Nevertheless, no biomarkers are at the moment available to track CI in MS patients. We aimed to explore the correlation of cerebrospinal fluid (CSF) axonal biomarkers, in particular: light-chain neurofilaments (NFL), Tau, and Beta-amyloid protein (Abeta) in MS patients with CI at the diagnosis. 62 newly diagnosed MS patients were enrolled, and cognition was evaluated using the Brief International Cognitive Assessment for MS (BICAMS) battery. CSF NFL, Abeta, and Tau levels were determined with commercial ELISA. Patients with CI (45.1%) did not differ for demographic, clinical, and MRI characteristics (except for lower educational level), but they displayed greater neurodegeneration, exhibiting higher mean CSF Tau protein (162.1 ± 52.96 pg/ml versus 132.2 ± 63.86 pg/ml p:0.03). No differences were observed for Abeta and NFL. The number of impaired tests and Tau were significantly correlated (r:0.32 p:0.01). Tau was higher in particular in patients with slowed information processing speed (IPS) (p:0.006) and a linear regression analysis accounting for EDSS, MRI, and MS subtype confirmed Tau as a weak predictor of IPS and cognitive impairment. In conclusion, CI has an important burden on the quality of life of MS patients and should be looked for even at diagnosis. Axonal damage biomarkers, and in particular Tau, seem to reflect cognition impairment in the early stages.

Cognitive Dysfunction in Multiple Sclerosis: Educational Level as a Protective Factor

Most people with MS experience cognitive deficits especially in attention, memory, information processing, and executive functions, negatively impacting on their quality of life. Cognitive variables of short-term memory, logical memory, and verbal fluency in 65 patients with multiple sclerosis (MS) were analysed in conjunction with sociodemographic variables such as sex, age, and educational level that might influence disease progression. We found that psychoeducational variables exerted a significant effect on the cognitive status of patients with MS. Thus, when considering sex, age, educational level, and type of MS (SPMS or RRMS), tests for between-subject effects revealed statistically significant differences in all three cognitive variables. In addition, we found that the type of MS and time since onset also generated significant cognitive differences. Our study shows that educational achievement or level is a protective factor against the disease, acting as a source of intellectual enrichment that promotes cognitive reserve in patients with MS. Further longitudinal studies assessing disease progression and prognosis in patients with MS would be useful in order to determine the specific importance of these variables in such patients and in strategies that could enhance their performance in neuropsychological assessment tasks.