Does focal inflammation have an impact on cognition in multiple sclerosis? An MRI study

Importance of Identifying Cognitive Impairment in Multiple Sclerosis

This article aims to highlight the impact of cognitive impairment on outcomes and quality of life for people with multiple sclerosis (MS) and to review current evidence for the efficacy of disease-modifying therapies (DMTs) and other interventions. In addition, we provide clinical practice insights regarding screening and management of cognitive impairment in people with MS. Evidence suggests that cognitive deterioration often accompanies magnetic resonance imaging changes. Neocortical volume and deep grey matter atrophy correlate with cognitive impairment. Similarly, cognitive decline is predictive of a higher lesion burden. Cognitive impairment is an important clinical measure of disability and negatively impacts quality of life. Phase 3 studies suggest that DMTs such as natalizumab, ozanimod and fingolimod may provide long-lasting, clinically meaningful effects on cognition in people with MS. Further data are needed to support the use of adjunct cognitive behavioural and exercise interventions for people with MS who have cognitive impairment. More data are needed to define appropriate management strategies for cognitive impairment in people with MS. Baseline and periodic screening for cognitive impairment and inclusion of cognitive impairment as a clinical trial endpoint will help to inform efforts to manage this important aspect of MS.

Long-term clinical, imaging and cognitive outcomes association with MS immunopathology

OBJECTIVE

In this observational study on a cohort of biopsy-proven central nervous system demyelinating disease consistent with MS, we examined the relationship between early-active demyelinating lesion immunopattern (IP) with subsequent clinical course, radiographic progression, and cognitive function.

METHODS

Seventy-five patients had at least one early-active lesion on biopsy and were pathologically classified into three immunopatterns based on published criteria. The median time from biopsy at follow-up was 11 years, median age at biopsy - 41, EDSS - 4.0. At last follow-up, the median age was 50, EDSS - 3.0. Clinical examination, cognitive assessment (CogState battery), and 3-Tesla-MRI (MPRAGE/FLAIR/T2/DIR/PSIR/DTI) were obtained.

RESULTS

IP-I was identified in 14/75 (19%), IP-II was identified in 41/75 (56%), and IP-III was identified in 18/75 (25%) patients. Patients did not differ significantly by immunopattern in clinical measures at onset or last follow-up. The proportions of disease courses after a median of 11 years were similar across immunopatterns, relapsing-remitting being most common (63%), followed by monophasic (32%). No differences in volumetric or DTI measures were found. CogState performance was similar for most tasks. A slight yet statistically significant difference was identified for episodic memory scores, with IP-III patients recalling one word less on average.

INTERPRETATION

In this study, immunopathological heterogeneity of early-active MS lesions identified at biopsy does not correlate with different long-term clinical, neuroimaging or cognitive outcomes. This could be explained by the fact that while active white matter lesions are pathological substrates for relapses, MS progression is driven by mechanisms converging across immunopatterns, regardless of pathogenic mechanisms driving the acute demyelinated plaque.

Cognitive Relapse in Multiple Sclerosis: New Findings and Directions for Future Research

Multiple sclerosis (MS) is a chronic inflammatory, demyelinating disease of the central nervous system, often presenting with brain atrophy and cognitive impairment (CI). In the relapsing–remitting phenotype, cognitive performance is increasingly recognized to decline acutely during MS relapse, with varying degrees of recovery afterwards. Therefore, CI in MS may result from incomplete recovery from episodes of so-called “cognitive relapse”, gradual neurodegeneration, or both. Among a variety of validated measures of cognitive performance, the Symbol Digit Modalities Test (SDMT) represents the most sensitive measure of cognitive decline and is easily translated to clinical practice. In fact, cognitive relapse identified using the SDMT has been reported in clinically relapsing cohorts as well as in individuals with no other neurological signs, suggesting that routine cognitive assessment may be necessary to fully appreciate the extent of a patient’s disease activity. The aim of this narrative review is as follows: (1) to provide the historical context for neuropsychological assessment in MS, (2) to provide a summation of key studies describing the cognitive relapse phenomenon, and (3) to discuss current gaps in our knowledge and highlight avenues for future research.

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.

Serum Vitamin D as a Marker of Impaired Information Processing Speed and Early Disability in Multiple Sclerosis Patients

Slowed information processing speed (IPS) is the hallmark and first cognitive domain to be altered in multiple sclerosis (MS) patients. Insufficient serum vitamin D was previously associated with disease development, relapses, and progression, but little is reported on cognition. However, vitamin D and cognitive impairment (CI) in other neurodegenerative diseases have already been linked. We explored the possible correlation between vitamin D and IPS at diagnosis and early disability at last follow-up in 81 MS patients. At diagnosis, we collected vitamin D levels and performed a Symbol Digit Modalities Test (SDMT). Raw scores were adjusted for age, gender, and educational level. Early disability was evaluated with MS severity score (MSSS) and age-related MSSS (ARMSS). A total of 71 patients (86.58%) showed hypovitaminosis D (19.71 ± 8.76 ng/mL) and 18 patients (21.95%) had CI. Patients with CI showed severe hypovitaminosis D (p = 0.004). No patients with sufficient vitamin D levels had CI. We found a positive correlation between vitamin D levels at diagnosis and (1) SDMT raw and z-score that persisted after correction for sunlight exposure and MRI baseline characteristics, and (2) EDSS, MSSS, and ARMSS after a mean 2 year follow-up. Low vitamin D levels may affect both cognition and early disability in newly diagnosed MS patients.

Event-related potentials and deep grey matter atrophy in multiple sclerosis: Exploring the possible associations with cognition

BACKGROUND

Event-related potentials (ERPs) have been proposed as a neurophysiological biomarker to capture cognitive dysfunction in multiple sclerosis (MS). Few studies have evaluated the relationships between ERPs and brain atrophy as known marker of structural brain damage related to cognitive impairment (CI).

OBJECTIVES

To explore the relationships of brain atrophy, including of the cortex and deep grey matter, with ERP abnormalities and cognitive function, as defined using the Brief Repeatable Battery of Neuropsychological Tests (BRBN).

RESULTS

Seventy-eight patients with relapsing-remitting MS were enroled, of which 38 (48.7%) had CI. Independent t-test comparisons of the ERP parameters found a significant difference in P300 wave latency, with a latency of 343.7 ± 32.6 ms in the CI group vs. 320.3 ± 16.5 ms in the cognitively preserved (CP) group (p = 0.001). Significant differences in the MRI measurements, including the cortex (p = 0.02) and deep grey matter structures [thalamus (p = 0.001), amygdala (p = 0.030), and nucleus accumbens (p = 0.004)) were observed, with lower measurements in the CI group. Regression models were also performed to explore the impact of brain volumes on ERP parameters. This showed a relationship between P300 latency and the lower amygdala (p = 0.02) and hippocampus (p = 0.03) volumes, while the amplitude of the P300 was significantly associated with a lower cortex volume (p = 0.01).

CONCLUSION

Cortex volume emerged as the most significant predictor of the P300 amplitude. The amygdala and hippocampal volumes were found to influence P300 latency, highlighting the role of deep grey matter atrophy in ERPs for the first time. The combination of structural MRI and neurophysiological techniques, sensitive to diverse aspects of MS pathology, could improve the understanding of CI in MS and its neurodegenerative and inflammatory substrate.

Cognitive impairment in an animal model of multiple sclerosis and its amelioration by glatiramer acetate

The severe motor impairment in the MS animal model experimental autoimmune encephalomyelitis (EAE) obstructs the assessment of cognitive functions. We developed an experimental system that evaluates memory faculties in EAE-affected mice, irrespective of their motor performance, enabling the assessment of cognitive impairments along the disease duration, the associated brain damage, and the consequences of glatiramer acetate (GA) treatment on these manifestations. The delayed-non-matching to sample (DNMS) T-maze task, testing working and long term memory was adapted and utilized. Following the appearance of clinical manifestations task performances of the EAE-untreated mice drastically declined. Cognitive impairments were associated with disease severity, as indicated by a significant correlation between the T-maze performance and the clinical symptoms in EAE-untreated mice. GA-treatment conserved cognitive functions, so that despite their exhibited mild motor impairments, the treated mice performed similarly to naïve controls. The cognitive deficit of EAE-mice coincided with inflammatory and neurodegenerative damage to the frontal cortex and the hippocampus; these damages were alleviated by GA-treatment. These combined findings indicate that in addition to motor impairment, EAE leads to substantial impairment of cognitive functions, starting at the early stages and increasing with disease aggravation. GA-treatment, conserves cognitive capacities and prevents its disease related deterioration.