Detection of altered hippocampal morphology in multiple sclerosis-associated depression using automated surface mesh modeling

A review on multiple sclerosis prognostic findings from imaging, inflammation, and mental health studies

Magnetic resonance imaging (MRI) of the brain is commonly used to detect where chronic and active lesions are in multiple sclerosis (MS). MRI is also extensively used as a tool to calculate and extrapolate brain health by way of volumetric analysis or advanced imaging techniques. In MS patients, psychiatric symptoms are common comorbidities, with depression being the main one. Even though these symptoms are a major determinant of quality of life in MS, they are often overlooked and undertreated. There has been evidence of bidirectional interactions between the course of MS and comorbid psychiatric symptoms. In order to mitigate disability progression in MS, treating psychiatric comorbidities should be investigated and optimized. New research for the prediction of disease states or phenotypes of disability have advanced, primarily due to new technologies and a better understanding of the aging brain.

rTMS ameliorates depression/anxiety-like behaviors in experimental autoimmune encephalitis by inhibiting neurotoxic reactive astrocytes

One third of patients with multiple sclerosis (MS) suffered from depressive symptoms. The pathogenesis of depression in MS patients has been related to innate immune activation in certain regions of the brain such as hippocampus. However, pharmacotherapy lacks sufficient evidence for beneficial effects on depression in MS patients, urging for a novel treatment modality for this mental disorder. Treatment effects of rTMS on depression/anxiety-like behaviors in mice with experimental autoimmune encephalomyelitis (EAE) were assessed by behavioral tests. The role of innate immune response was examined by RNA sequencing, quantitative RT-PCR, and immunofluorescence techniques. Depressive symptom severity and astroglial activation in patients with MS were assessed by Beck Depression Inventory and serum glial fibrillary acidic protein (GFAP), respectively. EAE mice displayed depression/anxiety-like behaviors, which were ameliorated by rTMS. Transcriptome and gene-specific expression analysis of the hippocampus showed significant reduction in transcript levels associated with neurotoxic reactive astrocytes in EAE mice after rTMS treatment. This was confirmed by immunofluorescence studies. Complement component 3d, a marker of neurotoxic reactive astrocytes, was highly expressed in EAE hippocampus, but was reduced to a basal level after rTMS treatment. In patients with MS, astroglial activation, indicated by serum GFAP levels, was significantly elevated in those with moderate or major depressive symptoms. These findings support that the suppression of neurotoxic reactive astrocytes might be a potential target for treatment of depression in patients with MS, and suggest the potential of using rTMS as a potential therapeutic treatment for this disorder.

Rosiglitazone Mitigates Dexamethasone-Induced Depression in Mice via Modulating Brain Glucose Metabolism and AMPK/mTOR Signaling Pathway

Major depressive disorder (MDD) is a common, complex disease with poorly understood pathogenesis. Disruption of glucose metabolism is implicated in the pathogenesis of depression. AMP-activated protein kinase (AMPK) has been shown to regulate the activity of several kinases, including pAKT, p38MAPK, and mTOR, which are important signaling pathways in the treatment of depression. This study tested the hypothesis that rosiglitazone (RGZ) has an antidepressant impact on dexamethasone (DEXA)-induced depression by analyzing the function of the pAKT/p38MAPK/mTOR pathway and NGF through regulation of AMPK. MDD-like pathology was induced by subcutaneous administration of DEXA (20 mg/kg) for 21 days in all groups except in the normal control group, which received saline. To investigate the possible mechanism of RGZ, the protein expression of pAMPK, pAKT, p38MAPK, and 4EBP1 as well as the levels of hexokinase, pyruvate kinase, and NGF were assessed in prefrontal cortex and hippocampal samples. The activities of pAMPK and NGF increased after treatment with RGZ. The administration of RGZ also decreased the activity of mTOR as well as downregulating the downstream signaling pathways pAKT, p38MAPK, and 4EBP1. Here, we show that RGZ exerts a potent inhibitory effect on the pAKT/p38MAPK/mTOR/4EBP1 pathway and causes activation of NGF in brain cells. This study has provided sufficient evidence of the potential for RGZ to ameliorate DEXA-induced depression. A new insight has been introduced into the critical role of NGF activation in brain cells in depression. These results suggest that RGZ is a promising antidepressant for the treatment of MDD.

Symptom Interconnectivity in Multiple Sclerosis: A Narrative Review of Potential Underlying Biological Disease Processes

Introduction

Fatigue, cognitive impairment, depression, and pain are highly prevalent symptoms in multiple sclerosis (MS). These often co-occur and may be explained by a common etiology. By reviewing existing literature, we aimed to identify potential underlying biological processes implicated in the interconnectivity between these symptoms.

Methods

A literature search was conducted to identify articles reporting research into the biological mechanisms responsible for the manifestation of fatigue, cognitive impairment, depression, and pain in MS. PubMed was used to search for articles published from July 2011 to July 2021. We reviewed and assessed findings from the literature to identify biological processes common to the symptoms of interest.

Results

Of 693 articles identified from the search, 252 were selected following screening of titles and abstracts and assessing reference lists of review articles. Four biological processes linked with two or more of the symptoms of interest were frequently identified from the literature: (1) direct neuroanatomical changes to brain regions linked with symptoms of interest (e.g., thalamic injury associated with cognitive impairment, fatigue, and depression), (2) pro-inflammatory cytokines associated with so-called ‘sickness behavior,’ including manifestation of fatigue, transient cognitive impairment, depression, and pain, (3) dysregulation of monoaminergic pathways leading to depressive symptoms and fatigue, and (4) hyperactivity of the hypothalamic–pituitary-adrenal (HPA) axis as a result of pro-inflammatory cytokines promoting the release of brain noradrenaline, serotonin, and tryptophan, which is associated with symptoms of depression and cognitive impairment.

Conclusion

The co-occurrence of fatigue, cognitive impairment, depression, and pain in MS appears to be associated with a common set of etiological factors, namely neuroanatomical changes, pro-inflammatory cytokines, dysregulation of monoaminergic pathways, and a hyperactive HPA axis. This association of symptoms and biological processes has important implications for disease management strategies and, eventually, could help find a common therapeutic pathway that will impact both inflammation and neuroprotection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-022-00368-2.

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.

Shape description and volumetry of hippocampus and amygdala in temporal lobe epilepsy - A beneficial combination with a clinical perspective

Shape-based markers have entered the field of morphometric neuroimaging analysis as a second mainstay alongside conventional volumetric approaches. We aimed to assess the added value of shape description for the analysis of lesional and autoimmune temporal lobe epilepsy (TLE) focusing on hippocampus and amygdala. We retrospectively investigated MRI and clinical data from 65 patients with lesional TLE (hippocampal sclerosis (HS) and astrogliosis) and from 62 patients with limbic encephalitis (LE) with serologically proven autoantibodies. Surface reconstruction and volumetric segmentation were performed with FreeSurfer. For the shape analysis, we used BrainPrint, a tool that utilizes eigenvalues of the Laplace-Beltrami operator on triangular meshes to calculate intra-subject asymmetry. Psychometric tests of memory performance were ascertained, to evaluate clinical relevance of the shape descriptor. The potential benefit of shape in addition to volumetric information for classification was assessed by five-fold repeated cross validation and logistic regression. For the LE group, the best performing classification model consisted of a combination of volume and shape asymmetry (mean AUC = 0.728), the logistic regression model was significantly improved considering both modalities instead of just volume asymmetry. For lesional TLE, the best model only considered volumetric information (mean AUC = 0.867). Shape asymmetry of the hippocampus was largely associated with verbal memory performance only in LE patients (OR = 1.07, p = 0.02). For lesional TLE, shape description is robust, but redundant when compared to volumetric approaches. For LE, in contrast, shape asymmetry as a complementary modality significantly improves the detection of subtle morphometric changes and is further associated with memory performance, which underscores the clinical relevance of shape asymmetry as a novel imaging biomarker.

Complement-associated loss of CA2 inhibitory synapses in the demyelinated hippocampus impairs memory

The complement system is implicated in synapse loss in the MS hippocampus, but the functional consequences of synapse loss remain poorly understood. Here, in post-mortem MS hippocampi with demyelination we find that deposits of the complement component C1q are enriched in the CA2 subfield, are linked to loss of inhibitory synapses and are significantly higher in MS patients with cognitive impairments compared to those with preserved cognitive functions. Using the cuprizone mouse model of demyelination, we corroborated that C1q deposits are highest within the demyelinated dorsal hippocampal CA2 pyramidal layer and co-localized with inhibitory synapses engulfed by microglia/macrophages. In agreement with the loss of inhibitory perisomatic synapses, we found that Schaffer collateral feedforward inhibition but not excitation was impaired in CA2 pyramidal neurons and accompanied by intrinsic changes and a reduced spike output. Finally, consistent with excitability deficits, we show that cuprizone-treated mice exhibit impaired encoding of social memories. Together, our findings identify CA2 as a critical circuit in demyelinated intrahippocampal lesions and memory dysfunctions in MS.

Dysfunction of the anterior and intermediate hippocampal functional network in major depressive disorders across the adult lifespan

Accumulating evidence indicates that structural and functional abnormalities in hippocampal formation are linked to major depressive disorder (MDD). However, the resting-state functional connectivity (RSFC) of hippocampal subfields in MDD remains unclear. This cross-sectional study aimed to investigate the RSFC of hippocampal subfields in a large sample of MDD patients. The results revealed that patients with MDD showed lower RSFC between the right anterior hippocampus and the insula, and the RSFC was inversely correlated with anxiety symptoms of depression. Depressed patients also showed decreased RSFC between the bilateral intermediate hippocampus and left nucleus accumbens (NAcc), and the hippocampus-NAcc circuit was negatively correlated with core symptoms of depression. The functional connectivity between the right anterior hippocampus and left postcentral gyrus increased with ageing in MDD patients compared with healthy controls. These findings suggest that the functional network of hippocampal subfields may underlie anxiety and core depression symptoms.

Relationship Between Interpersonal Depressive Symptoms and Reduced Amygdala Volume in People with Multiple Sclerosis: Considerations for Clinical Practice

Background

The lifetime prevalence of depression in people with multiple sclerosis (MS) is approximately 50% compared with around 15% in the general population. There is a relationship between depression and quality of life in people with MS and evidence that depression may contribute to disease progression.

Methods

This cross-sectional pilot study assessed the association between depression and regional brain atrophy, including amygdala and hippocampal volume. Forty-nine participants with MS recruited through a hospital MS clinic were administered the Center for Epidemiological Studies Depression Scale Revised (CESD-R) to investigate whether higher endorsements on the items depressive affect and interpersonal symptoms were associated with volumetric magnetic resonance imaging measurements of hippocampal and amygdala atrophy.

Results

Regression analysis revealed an association between depression-related interpersonal symptoms and right amygdala volume. No association was found between depression and hippocampal volume.

Conclusions

These results provide preliminary support for a unilateral, biologically based relationship between the right amygdala and characteristic interpersonal depressive symptoms expressed by people with MS and add to the growing body of literature implicating regional brain atrophy in MS-associated depression. Given that the interpersonal subcomponent of the CESD-R measures social functioning, and the neural networks in the amygdala are known to be implicated in processing social stimuli, this research suggests that targeted diagnosis and treatments for depression in people with MS may be particularly beneficial. Further confirmatory research of this relationship is required.

Selective morphological and volumetric alterations in the hippocampus of children exposed in utero to gestational diabetes mellitus

Prior epidemiological studies have found that in utero exposure to gestational diabetes mellitus (GDM) is associated with increased risk for neurodevelopmental disorders. However, brain alterations associated with GDM are not known. The hippocampus is pivotal for cognition and emotional regulation. Therefore, we assessed relationships between in utero exposure to GDM and hippocampal morphology and subfield structure during childhood. One hundred seventeen children aged 7–11 years (57% girls, 57% exposed to GDM), born at Kaiser Permanente Southern California, participated in the BrainChild Study. Maternal GDM status was determined from electronic medical records. Children underwent brain magnetic resonance imaging. Freesurfer 6.0 was used to measure hippocampal and individual hippocampal subfield gray matter volume (mm³). Morphological analyses on the hippocampal surface were carried out using shape analysis. GDM‐exposed children exhibited reduced radial thickness in a small, spatially‐restricted portion of the left inferior body of the hippocampus that corresponds to the CA1 subfield. There was a significant interaction between GDM‐exposure and sex on the right hippocampal CA1 subfield. GDM‐exposed boys had reduced right CA1 volume compared to unexposed boys, but this association was no longer significant after controlling for age. No significant group differences were observed in girls. Our results suggest that GDM‐exposure impacts shape of the left hippocampal CA1 subfield in both boys and girls and may reduce volume of right hippocampal CA1 only in boys. These in‐depth findings illuminate the unique properties of the hippocampus impacted by prenatal GDM‐exposure and could have important implications for hippocampal‐related functions.

Contributing Factors to the Quality of Life in Multiple Sclerosis

Introduction:

Multiple sclerosis (MS) is a chronic, inflammatory, (auto) immune disease of the central nervous system (CNS). Quality of life (QoL) refers to the perception of an individual’s life in the context of the system of culture and values in which they live.

Aim:

The aim of the study was to determine the distribution of cognitive disorders in people with MS.

Methods:

The prospective study included 135 participants with MS and 50 healthy participants. Participants were divided into three groups: the first group consisted of 85 participants where the disease lasted longer than one year, the second group consisted of 50 participants with newly diagnosed MS, the third group consisted of 50 healthy participants. The instruments of clinical assessment were: Extended Disability Score in Multiple Sclerosis Patients, Mini Mental Status, Beck Depression Scale, and Quality of Life Scale (SF-36, Contemporary Health Survey).

Results:

The quality of life related to health is impaired in the physical, mental dimension and overall quality of life. In the first group of participants, 62% had mild depression, and in the second group 38% of participants, while more severe forms were recorded in 16% of participants in both groups. As depression increases, the quality of life decreases in all measured dimensions, which would mean that depression negatively affects the quality of life. The results of all dimensions as well as the overall quality of life score are worse with the increase in the degree of clinical disability, for both groups of study patients.

Conclusion:

Quality of life is impaired in MS patients, and a higher degree of clinical disability and an increase in depressive disorder are predictors of deteriorating quality of life in MS patients.

Imaging and depression in multiple sclerosis: a historical perspective

PURPOSE

Patients affected with multiple sclerosis suffer from depression more frequently than the general population. Beyond psychosocial, genetic and immune-inflammatory factors, also the brain damage which is peculiar of multiple sclerosis has been claimed to have a role in the aetiology of depression in those patients. The study of this interesting relation has been implemented with both conventional and advanced magnetic resonance imaging techniques. The aim of this review is to provide a historical perspective on the link between multiple sclerosis-related depression and structural and functional brain damage.

METHODS

In this review, the results of the MRI studies regarding multiple sclerosis-related brain damage and the presence of depression are presented.

RESULTS

The findings of the reports reveal a link between brain pathology and depressive symptoms or the diagnosis of depression in multiple sclerosis.

CONCLUSIONS

Although a multifactorial aetiology has been theorized for depression and depressive symptoms in patients with multiple sclerosis, this review supports the hypothesis that the structural and functional brain impairment might substantially be amongst those factors. Thus, depression itself might be a symptom with a neuro-biological basis and not only the consequence of the disability derived from the neurological impairment.

An "Outside-In" and "Inside-Out" Consideration of Complement in the Multiple Sclerosis Brain: Lessons From Development and Neurodegenerative Diseases

The last 15 years have seen an explosion of new findings on the role of complement, a major arm of the immune system, in the central nervous system (CNS) compartment including contributions to cell migration, elimination of synapse during development, aberrant synapse pruning in neurologic disorders, damage to nerve cells in autoimmune diseases, and traumatic injury. Activation of the complement system in multiple sclerosis (MS) is typically thought to occur as part of a primary (auto)immune response from the periphery (the outside) against CNS antigens (the inside). However, evidence of local complement production from CNS-resident cells, intracellular complement functions, and the more recently discovered role of early complement components in shaping synaptic circuits in the absence of inflammation opens up the possibility that complement-related sequelae may start and finish within the brain itself. In this review, the complement system will be introduced, followed by evidence that implicates complement in shaping the developing, adult, and normal aging CNS as well as its contribution to pathology in neurodegenerative conditions. Discussion of data supporting "outside-in" vs. "inside-out" roles of complement in MS will be presented, concluded by thoughts on potential approaches to therapies targeting specific elements of the complement system.

The emotional disorders associated with multiple sclerosis

Multiple sclerosis (MS) is associated with a high prevalence of emotional and mood disorders. Emotional disorders may worsen during illness progression and affect the quality of life of patients and their families. MS is often associated with depression, with an increased risk of suicide, poor adherence to treatment, decreased functional status, and quality of life. The diagnosis and treatment of emotional and mood disorders in these patients is often challenging since several symptoms of these disorders overlap with those of MS. Other prevalent emotional disorders in MS include bipolar disorder, anxiety disorders, emotional blunting (apathy), and pseudobulbar affect. Early recognition and treatment of these comorbidities could contribute to the reduction of disability and even to decreased mortality. The aim of this chapter is to provide an up-to-date review of mood and emotional disorders that are often associated with MS, focusing on their epidemiology, clinical features, pathogenesis, assessment, and treatment. The interplay between the psychosocial impact of the chronic disability and the demyelinating structural lesions of the brain in precipitating emotional and mood disorders is discussed, as well as its implications for diagnosis and treatment.

Genetic Architecture of Depression: Where Do We Stand Now?

The research of depression genetics has been occupied by historical candidate genes which were tested by candidate gene association studies. However, these studies were mostly not replicable. Thus, genetics of depression have remained elusive for a long time. As research moves from candidate gene association studies to GWAS, the hypothesis-free non-candidate gene association studies in genome-wide level, this trend will likely change. Despite the fact that the earlier GWAS of depression were not successful, the recent GWAS suggest robust findings for depression genetics. These altogether will catalyze a new wave of multidisciplinary research to pin down the neurobiology of depression.

Transdiagnostic hippocampal damage patterns in neuroimmunological disorders

Hippocampal damage and associated cognitive deficits are frequently observed in neuroimmunological disorders, but comparative analyses to identify shared hippocampal damage patterns are missing. Here, we adopted a transdiagnostic analytical approach and investigated hippocampal shape deformations and associated cognitive deficits in four neuroimmunological diseases. We studied 120 patients (n = 30 in each group), including patients with multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), anti-NMDAR and anti-LGI1 encephalitis. A control group was matched to each patient sample from a pool of 79 healthy participants. We performed an MRI-based vertex-wise hippocampal shape analysis, extracted hippocampal volume estimates and scalar projection values as a measure of surface displacement. Cognitive testing included assessment of verbal memory and semantic fluency performance. Our cross-sectional analyses revealed characteristic patterns of bilateral inward deformations covering up to 32% of the hippocampal surface in MS, anti-NMDAR encephalitis, and anti-LGI1 encephalitis, whereas NMOSD patients showed no deformations compared to controls. Significant inversions were noted mainly on the hippocampal head, were accompanied by volume loss, and correlated with semantic fluency scores and verbal episodic memory in autoimmune encephalitis and MS. A deformation overlap analysis across disorders revealed a convergence zone on the left anterior hippocampus that corresponds to the CA1 subfield. This convergence zone indicates a shared downstream substrate of immune-mediated damage that appears to be particularly vulnerable to neuroinflammatory processes. Our transdiagnostic morphological view sheds light on mutual pathophysiologic pathways of cognitive deficits in neuroimmunological diseases and stimulates further research into the mechanisms of increased susceptibility of the hippocampus to autoimmunity.

Comorbid depression in medical diseases

Depression is one of the most common comorbidities of many chronic medical diseases including cancer and cardiovascular, metabolic, inflammatory and neurological disorders. Indeed, the prevalence of depression in these patient groups is often substantially higher than in the general population, and depression accounts for a substantial part of the psychosocial burden of these disorders. Many factors can contribute to the occurrence of comorbid depression, such as shared genetic factors, converging biological pathways, social factors, health behaviours and psychological factors. Diagnosis of depression in patients with a medical disorder can be particularly challenging owing to symptomatic overlap. Although pharmacological and psychological treatments can be effective, adjustments may need to be made for patients with a comorbid medical disorder. In addition, symptoms or treatments of medical disorders may interfere with the treatment of depression. Conversely, symptoms of depression may decrease adherence to treatment of both disorders. Thus, comprehensive treatment plans are necessary to optimize care.

Neuropsychiatric Symptoms of Multiple Sclerosis: State of the Art

Multiple Sclerosis (MS) is a chronic disabling neuroinflammatory disease. Psychiatric manifestations have a high prevalence in MS patients and may worsen the illness progression and the patients' quality of life (QoL). Depression is a highly prevalent condition in MS patients, associated with poorer adherence to treatment, decreased functional status and QoL, and increased suicide risk. Diagnosis and treatment of this disorder is challenging because of symptom overlap. Other prevalent psychiatric comorbidities are anxiety disorders, bipolar disorder, psychotic disorders, substance misuse and personality disorders. As the illness progresses, personality changes can happen, as well as affect abnormalities. Cognitive changes occur frequently in MS patients, and affect features like processing speed, attention, learning, memory, visual spatial capabilities, and some language deficits. Disease-modifying treatments may reduce cognitive impairment because of their container action on the brain's lesion burden. Other QoL determinants such as fatigue, pain, sexual dysfunction, exercise, resilience and social support should be taken into account, in order to promote the individuals' well-being. Further studies are needed in order to elucidate the effectiveness of pharmacotherapy and more neuroimaging studies are required to clarify the relationship between structural changes and psychiatric comorbidities.

Behavioural phenotypes in the cuprizone model of central nervous system demyelination

The feeding of cuprizone (CPZ) to animals has been extensively used to model the processes of demyelination and remyelination, with many papers adopting a narrative linked to demyelinating conditions like multiple sclerosis (MS), the aetiology of which is unknown. However, no current animal model faithfully replicates the myriad of symptoms seen in the clinical condition of MS. CPZ ingestion causes mitochondrial and endoplasmic reticulum stress and subsequent apoptosis of oligodendrocytes leads to central nervous system demyelination and glial cell activation. Although there are a wide variety of behavioural tests available for characterizing the functional deficits in animal models of disease, including that of CPZ-induced deficits, they have focused on a narrow subset of outcomes such as motor performance, cognition, and anxiety. The literature has not been systematically reviewed in relation to these or other symptoms associated with clinical MS. This paper reviews these tests and makes recommendations as to which are the most important in order to better understand the role of this model in examining aspects of demyelinating diseases like MS.

Functional connectivity impairment of postcentral gyrus in relapsing-remitting multiple sclerosis with somatosensory disorder

PURPOSE

To characterize the spatial patterns of functional connectivity(FC) changes of whole brain in RRMS with somatosensory disorder(RRMS-SS) and to investigate the correlation between abnormal FC and clinical scores.

METHODS

Twenty-six RRMS-SS patients and 23 healthy controls(HC) underwent resting-state functional magnetic resonance imaging(RS-fMRI) scanning. The clinical scores were collected including Expanded Disability Status Scores(EDSS), Disease Duration and Somatosensory Evaluation by the Fugl-Meyer sensory score(FMSS). With the voxel-wise methods, RS-fMRI data were analyzed using REST software, to assess the FC of the postcentral gyrus(PoCG). Correlation between clinical variables and the strength of FC was analyzed.

RESULTS

Compared with HC, the left postcentral-based FC showed decreased FC of the right cerebellum_8, lingual lobe and Rolandic operculum gyrus, and increased FC of the left middle frontal lobe. The right postcentral-based FC revealed decreased FC with the right Heschl's gyrus lobule, and increased FC with bilateral middle frontal lobe (p <  0.001, AlphaSim corrected). Correlation analysis revealed that the FC of altered brain regions was associated with FMSS, EDSS and disease duration.

CONCLUSION

The functional connectivity of PoCG at RS-fMRI has multi-network changes in patients with RRMS-SS. This suggests a complex pattern of abnormal connections between the somatosensory network regions and the whole brain. Moreover, the correlation between the FC and the FMSS, such as the left middle frontal lobe and the right PoCG, indicate that these two brain regions play an important role in RRMS-SS.

A complex relation between depression and multiple sclerosis: a descriptive review

BACKGROUND

Multiple sclerosis (MS) is a demyelinating neurodegenerative disease that affects central nervous system (CNS). MS patients are more likely to develop depressive symptoms than patients with other chronic diseases.

OBJECTIVE

In this review, we have analysed if there is a correlation between brain lesions (BL), structural damage (SD) and depressive symptoms (DS).

METHODS

We Searched on PubMed and Web of Science databases and screening references of included studied and some review article for additional citations. From initial 745 studies, only 9 met the inclusion criteria. All studies conducted research on 389 patients with MS associated with DS and 120 HC (healthy controls).

RESULTS

The selected researches highlighted the involvement of limbic system, the role of hippocampus and the impact of brain lesions on the emotional status of MS patients.

DISCUSSION

In the genesis of depression are implicated many mechanisms including genetic, biochemical, immunological and psychosocial factors, even if a prominent role in the onset of DS seem to be associated with structural and functional brain alterations.

The hippocampus in multiple sclerosis

Some of the clinical manifestations of multiple sclerosis, such as memory impairment and depression, are, at least partly, related to involvement of the hippocampus. Pathological studies have shown extensive demyelination, neuronal damage, and synaptic abnormalities in the hippocampus of patients with multiple sclerosis, and improvements in MRI technology have provided novel ways to assess hippocampal involvement in vivo. It is now accepted that clinical manifestations related to the hippocampus are due not only to focal hippocampal damage, but also to disconnection of the hippocampus from several brain networks. Evidence suggests anatomical and functional subspecialisation of the different hippocampal subfields, resulting in variability between regions in the extent to which damage and repair occur. The hippocampus also has important roles in plasticity and neurogenesis, both of which potentially contribute to functional preservation and restoration. These findings underline the importance of evaluation of the hippocampus not only to improve understanding of the clinical manifestations of multiple sclerosis, but also as a potential future target for treatment.

Multiple Immune-Inflammatory and Oxidative and Nitrosative Stress Pathways Explain the Frequent Presence of Depression in Multiple Sclerosis

Patients with a diagnosis of multiple sclerosis (MS) or major depressive disorder (MDD) share a wide array of biological abnormalities which are increasingly considered to play a contributory role in the pathogenesis and pathophysiology of both illnesses. Shared abnormalities include peripheral inflammation, neuroinflammation, chronic oxidative and nitrosative stress, mitochondrial dysfunction, gut dysbiosis, increased intestinal barrier permeability with bacterial translocation into the systemic circulation, neuroendocrine abnormalities and microglial pathology. Patients with MS and MDD also display a wide range of neuroimaging abnormalities and patients with MS who display symptoms of depression present with different neuroimaging profiles compared with MS patients who are depression-free. The precise details of such pathology are markedly different however. The recruitment of activated encephalitogenic Th17 T cells and subsequent bidirectional interaction leading to classically activated microglia is now considered to lie at the core of MS-specific pathology. The presence of activated microglia is common to both illnesses although the pattern of such action throughout the brain appears to be different. Upregulation of miRNAs also appears to be involved in microglial neurotoxicity and indeed T cell pathology in MS but does not appear to play a major role in MDD. It is suggested that the antidepressant lofepramine, and in particular its active metabolite desipramine, may be beneficial not only for depressive symptomatology but also for the neurological symptoms of MS. One clinical trial has been carried out thus far with, in particular, promising MRI findings.

Depression in Multiple Sclerosis: Epidemiology, Aetiology, Diagnosis and Treatment

Depressive disorders are common in patients with multiple sclerosis, influencing their quality of life and adherence to treatments, as well as becoming more frequent with the progression of the disease and in the secondary progressive form of multiple sclerosis. Patients with multiple sclerosis often experience a typical cluster of symptoms in association with depression, such as fatigue, pain and cognitive impairment. However, the pathogenesis of multiple sclerosis-related depression remains partially unclear, even though genetic, immune-inflammatory and psychosocial factors might be seen to play a role, in addition to the brain structural alterations documented by magnetic resonance imaging studies. The high incidence and burden of depression in people affected with multiple sclerosis are matters of crucial importance. Despite such importance, the efficacy of pharmacologic treatments has been poorly studied and, for the most part, the access to non-pharmacological treatments is partially dependent on the local health system availability. It has been determined that interferon-beta and glatiramer acetate do not cause depressive symptoms; however, no definitive data in this regard are avaible for the newer disease-modifyng medications. In this review, we discuss the diagnosis, prevalence, pathogenesis, clinical aspects, magnetic resonance imaging findings and treatments available in patients experiencing multiple sclerosis-related depression.

Does the presence of multiple sclerosis impact on symptom profile in depressed patients?

OBJECTIVE

Major depressive disorder (MDD) is common in patients with multiple sclerosis (MS) but may remain unrecognized because of overlapping symptoms and different presentation due to its specific MS-related neurobiological aetiology. We aimed to investigate the clinical profile of MDD in MS.

METHODS

In a sample of MDD patients with MS (n=83) and without MS (n=782), MDD characteristics, 30 depressive symptoms, and sum scores of cognitive, somatic, atypical and melancholic symptom clusters were compared using logistic regression analyses and analysis of co-variance.

RESULTS

MDD in MS was characterized by older age of onset (p<0.001), and fewer comorbid anxiety disorders (37% versus 72%; p<0.001). The symptom 'future pessimism' was more common in MS patients (OR=1.62; 95%CI=1.02-2.59). 'Diminished capacity for pleasure/enjoyment' (OR=0.44; 95%CI=0.24-0.78), 'increased appetite' (OR=0.40; 95%CI=0.19-0.85), 'arousal symptoms' (OR=0.49; 95%CI=0.28-0.84), and 'panic/phobic symptoms' (OR=0.49; 95%CI=0.29-0.84) were less common in MS patients. Twenty-five symptoms (83%) out of 30, including depression's core symptoms (sadness and loss of interest) were not differentially associated with MS and no differences existed for the symptom clusters.

CONCLUSION

Only subtle differences in depressive symptom profiles existed between MDD patients with and without MS. The clinical profile of depression remains valid among MS patients, although it presents with diminished anxiety distress and comorbidity.

Neuropsychiatric syndromes of multiple sclerosis

Neuropsychiatric signs and symptoms occur frequently in individuals with multiple sclerosis (MS), either as the initial presenting complaint prior to a definitive neurological diagnosis or more commonly with disease progression. However, the pathogenesis of these comorbid conditions remains unclear and it remains difficult to accurately elucidate if neuropsychiatric symptoms or conditions are indicators of MS illness severity. Furthermore, both the disease process and the treatments of MS can adversely impact an individual's mental health. In this review, we discuss the common neuropsychiatric syndromes that occur in MS and describe the clinical symptoms, aetiology, neuroimaging findings and management strategies for these conditions.

Radiologically isolated syndrome: An update on a rare entity

Our understanding of radiologically isolated syndrome (RIS) is evolving, as new data emerge on the clinical characterization and the pathophysiological nature of this rare entity. This topical review aims to (1) outline state-of-the-art clinical and magnetic resonance imaging findings of RIS research; (2) raise the main obstacles to RIS research; (3) discuss the most controversial issues of current RIS findings; and (4) highlight potential strategies for upcoming research studies.

Hippocampal Neuroinflammation, Functional Connectivity, and Depressive Symptoms in Multiple Sclerosis

BACKGROUND

Depression, a condition commonly comorbid with multiple sclerosis (MS), is associated more generally with elevated inflammatory markers and hippocampal pathology. We hypothesized that neuroinflammation in the hippocampus is responsible for depression associated with MS. We characterized the relationship between depressive symptoms and hippocampal microglial activation in patients with MS using the 18-kDa translocator protein radioligand [(18)F]PBR111. To evaluate pathophysiologic mechanisms, we explored the relationships between hippocampal neuroinflammation, depressive symptoms, and hippocampal functional connectivities defined by resting-state functional magnetic resonance imaging.

METHODS

The Beck Depression Inventory (BDI) was administered to 11 patients with MS and 22 healthy control subjects before scanning with positron emission tomography and functional magnetic resonance imaging. We tested for higher [(18)F]PBR111 uptake in the hippocampus of patients with MS relative to healthy control subjects and examined the correlations between [(18)F]PBR111 uptake, BDI scores, and hippocampal functional connectivities in the patients with MS.

RESULTS

Patients with MS had an increased hippocampal [(18)F]PBR111 distribution volume ratio relative to healthy control subjects (p = .024), and the hippocampal distribution volume ratio was strongly correlated with the BDI score in patients with MS (r = .86, p = .006). Hippocampal functional connectivities to the subgenual cingulate and prefrontal and parietal regions correlated with BDI scores and [(18)F]PBR111 distribution volume ratio.

CONCLUSIONS

Our results provide evidence that hippocampal microglial activation in MS impairs the brain functional connectivities in regions contributing to maintenance of a normal affective state. Our results suggest a rationale for the responsiveness of depression in some patients with MS to effective control of brain neuroinflammation. Our findings also lend support to further investigation of the role of inflammatory processes in the pathogenesis of depression more generally.

Individual differences in depression are associated with abnormal function of the limbic system in multiple sclerosis patients

Background:

Depression is common in patients with multiple sclerosis (MS), although the brain mechanisms of this psychiatric condition in MS are poorly understood. Specifically, it remains to be determined whether depression in MS is related to altered activity and functional connectivity patterns within limbic circuits.

Methods:

Seventy-seven MS patients with variable levels of depression (as assessed via the Beck Depression Inventory) underwent functional magnetic resonance imaging while performing an emotional processing task. To conduct the functional connectivity analyses, the bilateral amygdala and hippocampus, two areas critically involved in the pathophysiology of depression, were chosen as ‘seed’ regions. Multiple regression models were used to assess how depression in MS patients was correlated with the activity and functional connectivity patterns within the limbic system.

Results:

Depression scores in MS patients were negatively correlated: (1) with the activity in the subgenual cingulate cortex; (2) with the functional connectivity between the hippocampus and orbitofrontal cortex as well as the dorsolateral prefrontal cortex, and (3) with the functional connectivity between the amygdala and dorsolateral prefrontal cortex.

Conclusions:

Our study showed that individual differences in depression in MS patients were significantly associated with altered regional activity and functional connectivity patterns within the limbic system.

Hippocampal-DMN disconnectivity in MS is related to WM lesions and depression

The hippocampus is part of the default-mode network (DMN) and is functionally hit early in multiple sclerosis (MS). Hippocampal and DMN dysfunctions have been associated with depression, both in patients with MS and in major depressive disorders. We hypothesized that white matter lesions may contribute, through a disconnection mechanism, to hippocampal dysfunction. To test this, we assessed the relationship between hippocampal resting-state (RS) functional connectivity (FC) abnormalities with brain T2 lesion volumes and the presence and severity of depression. Structural and RS fMRI images were acquired from 69 patients with cognitively intact MS and 42 matched healthy controls (HC). Depression was quantified using the Montgomery-Asberg Depression Rating Scale. Seed-voxel hippocampal RS FC was assessed. SPM8 was used for between-group comparisons and correlation analysis between RS FC abnormalities with clinical and structural MRI variables. Compared to HC, patients with MS showed a significant atrophy of the whole brain and left hippocampus (P < 0.001), and a distributed pattern of decreased RS FC between the hippocampi and several cortical-subcortical regions, which were mostly located within the DMN. Reduced hippocampal RS FC with regions of the DMN was strongly correlated with higher T2 lesion volume, longer disease duration, and the severity of depression and disability. In patients with cognitively preserved MS, brain focal WM lesions are related to the functional integration of the hippocampus to other brain regions of the DMN, suggesting a disconnection syndrome. Such a disruption of hippocampal RS FC is likely to contribute to the occurrence of depression and to clinical disability.

Diagnostic accuracy for major depression in multiple sclerosis using self-report questionnaires

OBJECTIVE

Multiple sclerosis and major depressive disorder frequently co-occur but depression often remains undiagnosed in this population. Self-rated depression questionnaires are a good option where clinician-based standardized diagnostics are not feasible. However, there is a paucity of data on diagnostic accuracy of self-report measures for depression in multiple sclerosis (MS). Moreover, head-to-head comparisons of common questionnaires are largely lacking. This could be particularly relevant for high-risk patients with depressive symptoms. Here, we compare the diagnostic accuracy of the Beck Depression Inventory (BDI) and 30-item version of the Inventory of Depressive Symptomatology Self-Rated (IDS-SR30) for major depressive disorder (MSS) against diagnosis by a structured clinical interview.

METHODS

Patients reporting depressive symptoms completed the BDI, the IDS-SR30 and underwent diagnostic assessment (Mini International Neuropsychiatric Interview, M.I.N.I.). Receiver-Operating Characteristic analyses were performed, providing error estimates and false-positive/negative rates of suggested thresholds.

RESULTS

Data from n = 31 MS patients were available. BDI and IDS-SR30 total score were significantly correlated (r = 0.82). The IDS-SR30total score, cognitive subscore, and BDI showed excellent to good accuracy (area under the curve (AUC) 0.86, 0.91, and 0.85, respectively).

CONCLUSION

Both the IDS-SR30 and the BDI are useful to quantify depressive symptoms showing good sensitivity and specificity. The IDS-SR30 cognitive subscale may be useful as a screening tool and to quantify affective/cognitive depressive symptomatology.

Psychiatric disturbances in radiologically isolated syndrome

BACKGROUND

Radiologically isolated syndrome (RIS) is characterized by incidental lesions suggestive of multiple sclerosis (MS) on MRI without typical symptoms of MS. Clinically isolated syndrome (CIS) is characterized by a first episode of neurologic symptoms caused by demyelination in the central nervous system. To date, psychiatric disorders have not been systematically addressed in RIS subjects. We assessed emotional disturbances, personality features and health-related quality of life (HRQoL) in a cohort of RIS patients as compared with clinically isolated syndrome (CIS).

METHODS

Twenty-eight RIS patients, 25 clinically isolated syndrome (CIS) patients, and 22 healthy subjects were enrolled in the study. Participants were administered a mood scale (Hamilton Depression Rating Scale), behavioural measures (Personality Assessment Inventory), and fatigue measures (Fatigue Impact Scale for Daily Use). HRQoL was quantified using the EuroQol-5.

RESULTS

14 (50%) of RIS patients had clinically significant depression, with over one-third of these having moderate depression, scores virtually identical to those observed in CIS patients. 11 of 28 (39.3%) subjects with RIS had anxious depression, a figure three times higher than that found in CIS patients. RIS patients' HAMD-17 total score showed a very strong correlation with severity of fatigue. In addition, RIS patients reported lower HRQoL (p = 0.036) and a significantly higher symptoms load for somatisation compared to both CIS and control groups (p < 0.002).

CONCLUSION

RIS patients had high rates of depression, particularly anxious depression and somatization. Future studies are warranted to clarify whether these psychiatric disturbances are causally associated with a distinct white matter psychopathologic process.

In vivo evidence of hippocampal dentate gyrus expansion in multiple sclerosis

Using MR-based radial mapping, we assessed morphological alterations of the hippocampal dentate gyrus (DG) in patients with relapse-onset multiple sclerosis (MS). We analyzed different stages of the disease and the association of DG alterations with hippocampal-related cognitive functions. Using high-resolution morphological imaging, hippocampal radial mapping analysis was performed in 28 relapsing-remitting (RR), 34 secondary progressive, and 26 benign MS patients and 28 healthy controls (HC). Between-groups differences of DG radial distance (from surface points to the central core of the hippocampus) and correlations with clinical, neuropsychological, and radiological measures were evaluated using surface-based mesh modeling. Compared with HC, all MS clinical phenotypes revealed a larger radial distance of the DG, which was more marked on the left side. Radial distance enlargement was more pronounced in RRMS patients compared with the other disease clinical phenotypes and was inversely correlated to disease duration. Radial distance enlargement was correlated with higher T2 lesion volume and a better cognitive performance in RRMS and with a poor cognitive performance in secondary progressive and benign MS patients. Surface expansion of the DG might represent an inflammation-induced neurogenic (reactive) process of the subgranular zone of the hippocampus primarily aimed at rescuing the functional competence of hippocampal circuitry.

The hippocampus in aging and disease: From plasticity to vulnerability

The hippocampus has a pivotal role in learning and in the formation and consolidation of memory and is critically involved in the regulation of emotion, fear, anxiety, and stress. Studies of the hippocampus have been central to the study of memory in humans and in recent years, the regional specialization and organization of hippocampal functions have been elucidated in experimental models and in human neurological and psychiatric diseases. The hippocampus has long been considered a classic model for the study of neuroplasticity as many examples of synaptic plasticity such as long-term potentiation and -depression have been identified and demonstrated in hippocampal circuits. Neuroplasticity is the ability to adapt and reorganize the structure or function to internal or external stimuli and occurs at the cellular, population, network or behavioral level and is reflected in the cytological and network architecture as well as in intrinsic properties of hippocampal neurons and circuits. The high degree of hippocampal neuroplasticity might, however, be also negatively reflected in the pronounced vulnerability of the hippocampus to deleterious conditions such as ischemia, epilepsy, chronic stress, neurodegeneration and aging targeting hippocampal structure and function and leading to cognitive deficits. Considering this framework of plasticity and vulnerability, we here review basic principles of hippocampal anatomy and neuroplasticity on various levels as well as recent findings regarding the functional organization of the hippocampus in light of the regional vulnerability in Alzheimer's disease, ischemia, epilepsy, neuroinflammation and aging.

Brain MRI lesions and atrophy are associated with employment status in patients with multiple sclerosis

Multiple sclerosis (MS) commonly affects occupational function. We investigated the link between brain MRI and employment status. Patients with MS (n = 100) completed a Work Productivity and Activity Impairment (WPAI) (general health version) survey measuring employment status, absenteeism, presenteeism, and overall work and daily activity impairment. Patients “working for pay” were considered employed; “temporarily not working but looking for work,” “not working or looking for work due to age,” and “not working or looking for work due to disability” were considered not employed. Brain MRI T1 hypointense (T1LV) and T2 hyperintense (T2LV) lesion volumes were quantified. To assess lesional destructive capability, we calculated each subject’s ratio of T1LV to T2LV (T1/T2). Normalized brain parenchymal volume (BPV) assessed brain atrophy. The mean (SD) age was 45.5 (9.7) years; disease duration was 12.1 (8.1) years; 75 % were women, 76 % were relapsing-remitting, and 76 % were employed. T1LV, T1/T2, Expanded Disability Status Scale (EDSS) scores, and activity impairment were lower and BPV was higher in the employed vs. not employed group (Wilcoxon tests, p < 0.05). Age, disease duration, MS clinical subtype, and T2LV did not differ between groups (p > 0.05). In multivariable logistic regression modeling, adjusting for age, sex, and disease duration, higher T1LV predicted a lower chance of employment (p < 0.05). Pearson correlations showed that EDSS was associated with activity impairment (p < 0.05). Disease duration, age, and MRI measures were not correlated with activity impairment or other WPAI outcomes (p > 0.05). We report a link between brain atrophy and lesions, particularly lesions with destructive potential, to MS employment status.

Emotional dysfunctions in neurodegenerative diseases

Neurodegenerative diseases are characterized primarily by motor signs but are also accompanied by emotional disturbances. Because of the limited knowledge about these dysfunctions, this Review provides an overview of emotional competencies in Huntington's disease (HD), Parkinson's disease (PD), and multiple sclerosis (MS), with a focus on emotion recognition, emotion regulation, and depression. Most studies indicate facial emotion recognition deficits in HD and PD, whereas data for MS are inconsistent. On a neural level, dysfunctions of amygdala and striatum, among others, have been linked to these impairments. These dysfunctions also tap brain regions that are part of the emotion regulation network, suggesting problems in this competency, too. Research points to dysfunctional emotion regulation in MS, whereas findings for PD and HD are missing. The high prevalence of depression in all three disorders emphasizes the need for effective therapies. Research on emotional disturbances might improve treatment, thereby increasing patients' and caregivers' well-being.

Complement C1q-C3-associated synaptic changes in multiple sclerosis hippocampus

OBJECTIVE

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system, leading to memory impairment in up to 65% of patients. Memory dysfunction in MS has been associated with loss of synapses in the hippocampus, but its molecular basis is unknown. Accumulating evidence suggests that components of the complement system, C1q and C3, can mediate elimination of synapses.

METHODS

To investigate the involvement of complement in synaptic changes in MS, gene and protein expression and localization of C1q and C3 were analyzed in relation to neuropathological changes in myelinated and demyelinated hippocampi from postmortem MS brains. Findings were compared to hippocampi of Alzheimer disease (AD) and non-neurological controls.

RESULTS

C1q expression and C3 activation were increased in myelinated and demyelinated MS hippocampi, mainly in the CA3/2 and CA1 subfields, which also showed a marked decrease in synaptic density and increased neuronal staining for the mitochondrial heat shock protein 70 (mtHSP70) stress marker. Neurons were the major source of C1q mRNA. C1q protein and activated C3 localized at synapses within human leukocyte antigen-positive cell processes and lysosomes, suggesting engulfment of complement-tagged synapses by microglia. A significant association (p < 0.0001) between the density of C1q and synaptophysin-positive synapses or mtHSP70 was seen in myelinated MS hippocampi, further pointing toward a link between the complement pathway and synaptic changes. In contrast to AD, MS hippocampi were consistently negative for the terminal complement activation complex C5b9.

INTERPRETATION

These data support a role for the C1q-C3 complement axis in synaptic alterations in the MS hippocampus.

Major depressive episodes over the course of 7 years and hippocampal subfield volumes at 7 tesla MRI: the PREDICT-MR study

INTRODUCTION

Smaller hippocampal volumes have been associated with major depressive disorder (MDD). The hippocampus consists of several subfields that may be differentially related to MDD. We investigated the association of occurrence of major depressive episodes (MDEs), assessed five times over seven years, with hippocampal subfield and entorhinal cortex volumes at 7 tesla MRI.

METHODS

In this prospective study of randomly selected general practice attendees, MDEs according to DSM-IV-R criteria were assessed at baseline and after 6, 12, 39 and 84 months follow-up. At the last follow-up, a T2 (0.7 mm(3)) 7 tesla MRI scan was obtained in 47 participants (60±10 years). The subiculum, cornu ammonis (CA) 1 to 3, dentate gyrus&CA4 and entorhinal cortex volumes were manually segmented according a published protocol.

RESULTS

Of the 47 participants, 13 had one MDE and 5 had multiple MDEs. ANCOVAs, adjusted for age, sex, education and intracranial volume, revealed no significant differences in hippocampal subfield or entorhinal cortex volumes between participants with and without an MDE in the preceding 84 months. Multiple episodes were associated with smaller subiculum volumes (B=-0.03 mL/episode; 95% CI -0.06; -0.003), but not with the other hippocampal subfield volumes, entorhinal cortex, or total hippocampal volume.

LIMITATIONS

A limitation of this study is the small sample size which makes replication necessary.

CONCLUSIONS

In this exploratory study, we found that an increasing number of major depressive episodes was associated with smaller subiculum volumes in middle-aged and older persons, but not with smaller volumes in other hippocampal subfields or the entorhinal cortex.

Thalamic-hippocampal-prefrontal disruption in relapsing-remitting multiple sclerosis

Background

Cortical, thalamic and hippocampal gray matter atrophy in relapsing–remitting MS (RRMS) is associated cognitive deficits. However, the role of interconnecting white matter pathways including the fornix, cingulum, and uncinate fasciculus (UF) is less well studied.

Objective

To assess MS damage to a hippocampal–thalamic–prefrontal network and the relative contributions of its components to specific cognitive domains.

Methods

We calculated diffusion tensor fractional anisotropy (FA) in the fornix, cingulum and UF as well as thalamic and hippocampal volumes in 27 RRMS patients and 20 healthy controls. A neuropsychological battery was administered and 4 core tests known to be sensitive to MS changes were used to assess cognitive impairment. To determine the relationships between structure and cognition, all tests were grouped into 4 domains: attention/executive function, processing speed, verbal memory, and spatial memory. Univariate correlations with structural measures and depressive symptoms identified potential contributors to cognitive performance and subsequent linear regression determined their relative effects on performance in each domain. For significant predictors, we also explored the effects of laterality and axial versus radial diffusivity.

Results

RRMS patients had worse performance on the Symbol Digit Modalities Test, but no significant impairment in the 4 cognitive domains. RRMS had reduced mean FA of all 3 pathways and reduced thalamic and hippocampal volumes compared to controls. In RRMS we found that thalamic volume and BDI predicted attention/executive function, UF FA predicted processing speed, thalamic volume predicted verbal memory, and UF FA and BDI predicted spatial memory.

Conclusions

Hippocampal–thalamic–prefrontal disruption affects cognitive performance in early RRMS with mild to minimal cognitive impairment, confirming both white and gray matter involvement in MS and demonstrating utility in assessing functional networks to monitor cognition.

•

We detect limbic white matter and gray matter insult in early RRMS patients with mild to minimal cognitive impairment.

•

Thalamic atrophy and uncinate fasciculus microstructural changes are associated with cognitive performance in early RRMS.

•

Depressive symptomatology also independently predicts cognitive performance

Structural 'connectomic' alterations in the limbic system of multiple sclerosis patients with major depression

BACKGROUND

Major depression (MD) is a common psychiatric disorder in multiple sclerosis (MS). Despite the negative impact of MD on the quality of life of MS patients, little is known about its underlying brain mechanisms.

OBJECTIVE

We studied the whole-brain connectivity patterns that were associated with MD in MS. Alterations were mainly expected within limbic circuits.

METHODS

Diffusion tensor imaging data were collected in 20 MS patients with MD, 22 non-depressed MS patients and 16 healthy controls. We used deterministic tractography and graph analysis to study the white-matter connectivity patterns that characterized MS patients with MD.

RESULTS

We found that MD in MS was associated with increased local path length in the right hippocampus and right amygdala. Further analyses revealed that these effects were driven by an increased shortest distance between both the right hippocampus and right amygdala and a series of regions including the dorsolateral and ventrolateral prefrontal cortex, orbitofrontal cortex, sensory-motor cortices and supplementary motor area.

CONCLUSION

Our data provide strong support for neurobiological accounts positing that MD in MS is mediated by abnormal 'communications' within limbic circuits. We also found evidence that MD in MS may be linked with connectivity alterations at the limbic-motor interface, a group of regions that translates emotions into survival-oriented behaviors.

The link between multiple sclerosis and depression

Depression--be it a formal diagnosis based on consensus clinical criteria, or a collection of symptoms revealed by a self-report rating scale--is common in patients with multiple sclerosis (MS) and adds substantially to the morbidity and mortality associated with this disease. This Review discusses the prevalence and epidemiology of depression in patients with MS, before covering aetiological factors, including genetics, brain pathology, immunological changes, dysregulation of the hypothalamic-pituitary-adrenal axis, and psychosocial influences. Treatment options such as antidepressant drugs, cognitive-behavioural therapy, mindfulness-based therapy, exercise and electroconvulsive therapy are also reviewed in the context of MS-related depression. Frequent comorbid conditions, namely pain, fatigue, anxiety, cognitive dysfunction and alcohol use, are also summarized. The article then explores three key challenges facing researchers and clinicians: what is the optimal way to define depression in the context of diseases such as MS, in which the psychiatric and neurological symptoms overlap; how can current knowledge about the biological and psychological underpinnings of MS-related depression be used to boost the validity of this construct; and can intervention be made more effective through use of combination therapies with additive or synergistic effects, which might exceed the modest benefits derived from their individual components?

Pain and cognition in multiple sclerosis

There is a high prevalence of pain, depression, and cognitive dysfunction in patients with Multiple Sclerosis (MS). These symptoms affect daily tasks resulting in a significant reduction in quality of life. Pain and cognitive changes have been studied across various animal models of MS. In these models the onset of pain and cognitive dysfunction occur early, and do not coincide with the pattern of motor deficits. This is likely underpinned by a number of different mechanisms including changes in glutamate transmission, glial cell activation, and increased levels of pro-inflammatory cytokines. Changes in pain and cognition have been described as belonging to a cluster of symptoms and have been linked through centrally driven processes. In particular, the overactive immune response can induce a state of "sickness-like behaviours" that can influence both pain and cognition. Investigating the mechanism of inflammatory sickness behaviors in MS could lead to a better understanding of the links between pain and cognition. There are currently few effective treatments for pain and cognition dysfunction in MS. Studying the relationship between these symptoms will allow better management of both symptoms.

Depressive syndromes in neurological disorders

Depressive syndromes represent a common and often characteristic feature in a number of neurological disorders. One prominent example is the development of post-stroke depression, which can be observed in more than one-third of stroke survivors in the aftermath of an ischemic stroke. Thus, post-stroke depression represents one of the most prevalent, disabling, and potentially devastating psychiatric post-stroke complications. On the other hand, depressive syndromes may also be considered as a risk factor for certain neurological disorders, as recently revealed by a meta-analysis of prospective cohort studies, which demonstrated an increased risk for ischemic events in depressed patients. Moreover, depressive syndromes represent common comorbidities in a number of other neurological disorders such as Parkinson's disease, multiple sclerosis, or epilepsy, in which depression has a strong impact on both quality of life and outcome of the primary neurological disorder.

Influence of the topography of brain damage on depression and fatigue in patients with multiple sclerosis

Objectives:

Involvement of selected central nervous system (CNS) regions has been associated with depression and fatigue in MS. We assessed whether specific regional patterns of lesion distribution and atrophy of the gray (GM) and white matter (WM) are associated with these symptoms in MS.

Methods:

Brain dual-echo and 3D T1-weighted images were acquired from 123 MS patients (69 depressed (D), 54 non-depressed (nD), 64 fatigued, 59 non-fatigued) and 90 controls. Lesion distribution, GM and WM atrophy were estimated using VBM and SPM8.

Results:

Gender, age, disease duration and conventional MRI characteristics did not differ between D-MS and nD-MS patients. Fatigued patients experienced higher EDSS and depression than non-fatigued ones. Lesion distribution and WM atrophy were not related to depression and fatigue. Atrophy of regions in the frontal, parietal and occipital lobes had a combined effect on depression and fatigue. Atrophy of the left middle frontal gyrus and right inferior frontal gyrus were selectively related to depression. No specific pattern of GM atrophy was found to be related to fatigue.

Conclusions:

Depression in MS is linked to atrophy of cortical regions located in the bilateral frontal lobes. A distributed pattern of GM atrophy contributes to the concomitant presence of depression and fatigue in these patients.

Morphostructural MRI abnormalities related to neuropsychiatric disorders associated to multiple sclerosis

Multiple Sclerosis associated neuropsychiatric disorders include major depression (MD), obsessive-compulsive disorder (OCD), bipolar affective disorder, euphoria, pseudobulbar affect, psychosis, and personality change. Magnetic Resonance Imaging (MRI) studies focused mainly on identifying morphostructural correlates of MD; only a few anecdotal cases on OCD associated to MS (OCD-MS), euphoria, pseudobulbar affect, psychosis, personality change, and one research article on MRI abnormalities in OCD-MS have been published. Therefore, in the present review we will report mainly on neuroimaging abnormalities found in MS patients with MD and OCD. All together, the studies on MD associated to MS suggest that, in this disease, depression is linked to a damage involving mainly frontotemporal regions either with discrete lesions (with those visible in T1 weighted images playing a more significant role) or subtle normal appearing white matter abnormalities. Hippocampal atrophy, as well, seems to be involved in MS related depression. It is conceivable that grey matter pathology (i.e., global and regional atrophy, cortical lesions), which occurs early in the course of disease, may involve several areas including the dorsolateral prefrontal cortex, the orbitofrontal cortex, and the anterior cingulate cortex whose disruption is currently thought to explain late-life depression. Further MRI studies are necessary to better elucidate OCD pathogenesis in MS.