APOE and risk of cognitive impairment in multiple sclerosis

Molecular biomarkers and cognitive impairment in multiple sclerosis: State of the field, limitations, and future direction - A systematic review and meta-analysis

OBJECTIVE

Multiple sclerosis (MS) is associated with cognitive impairment (CI) such as slowed information processing speed (IPS). Currently, no immunocellular or molecular markers have been established in cerebrospinal fluid and serum analysis as surrogate biomarkers with diagnostic or predictive value for the development of CI. This systematic review and meta-analysis aims to sum up the evidence regarding currently discussed markers for CI in MS.

METHODS

A literature search was conducted on molecular biomarkers of CI in MS, such as neurofilament light chain, chitinases, and vitamin D.

RESULTS

5543 publications were screened, of which 77 entered the systematic review. 13 studies were included in the meta-analysis. Neurofilament light chain (CSF: r_p = -0.294, p = 0.003; serum: r_p = -0.137, p = 0.001) and serum levels of vitamin D (r_p = 0.190, p = 0.014) were associated with IPS outcomes.

CONCLUSIONS

Neurofilament light chain and vitamin D are promising biomarkers to track impairments in IPS in MS. Further longitudinal research is needed to establish the use of molecular biomarkers to monitor cognitive decline.

Association of APOE Serum Levels and APOE ε2, ε3, and ε4 Alleles with Optic Neuritis

Optical neuritis (ON), otherwise known as optical nerve damage, is a term used to describe various environmental and body conditions that lead to optic nerve dysfunction. Neurologists are well aware of conditions that cause optic neuropathy, such as trauma, infections, malnutrition, and various toxins. As optic neuritis is a multifactorial demyelinating or infectious process, genetic predisposition may also influence the progression of optic neuritis. This study aimed to evaluate the association of ON (with and without multiple sclerosis) with APOE alleles and APOE serum levels. We found that the APOE ε3/ε3 genotype was statistically less common in the ON group of males than in the control group (p = 0.045). Moreover, the APOE ε3/ε3 genotype had a 3.7-fold increase in the odds of ON development in males (OR = 3.698; CI: 1.503–9.095; p = 0.004). In contrast, the APOE ε3/ε4 genotype had a 4.1-fold decrease in the odds of ON development in males (OR = 0.242; CI: 0.083–0.704; p = 0.009). APOE serum levels were statistically significantly higher in the ON group than in the control group (p = 0.042). The APOE ε3/ε3 genotype may increase males’ risk of developing ON, while the ε3/ε4 genotype may reduce males’ risk of developing ON.

ApoE4-positive multiple sclerosis patients are more likely to have cognitive impairment: a cross-sectional study

BACKGROUND

Multiple sclerosis (MS) presents with a wide variety of symptoms, including cognitive dysfunction. Previous studies in terms of the possible function of the ApoE4 allele as a risk factor for cognitive dysfunction in MS patients were associated with conflicting results. The role of the ε4 isoform of apolipoprotein (ApoE4) was investigated in this study as a risk factor for cognitive dysfunction in MS patients.

METHODS

Mildly disabled relapsing-remitting MS (RRMS) patients were involved in this study. The neurocognitive assessment is conducted by the Minimal Assessment of Cognitive Function in MS (MACFIMS) battery. After determining the genotype, patients were divided into two groups of ApoE4-positive and ApoE4-negative groups, and cognitive findings were compared.

RESULTS

Seventy-one patients with a mean age of 31.43 ± 8.75 were involved in this study. Eleven out of 17 (64.70%) patients in the ApoE4-positive group had at least one impaired test, while this rate was 16 out of 54 (29.62%) in the ApoE4-negative group (p < 0.01). The rate of overall cognitive impairment (failure in ≥ 2 tests) was not statistically different between groups of the study (p = 0.75). Impairment in Paced Auditory Serial Addition Test (PASAT) task and also the mean score of Brief Visuospatial Memory Test-Revised (BVMT-R) tests were different between two groups (p = 0.01 and 0.02, respectively).

CONCLUSION

MS ApoE4-positive patients are more likely to have at least one impaired cognitive test, but there is a need for more studies with larger sample sizes and based on MS-specific cognitive tests to confirm these findings.

ApoE and Neurodegenerative Diseases in Aging

Age and apolipoprotein E (ApoE) are the mightiest risk factors for dementia and cardiovascular diseases, but the underlying mechanisms remain unclear. In human, ApoE has three isoforms, ApoE2, ApoE3, and ApoE4, which are expressed by the polymorphic alleles: ɛ2, ɛ3, and ɛ4. Among the three polymorphic alleles, apoE ε4 is the most risk gene. ApoE is the main ligand for the low-density lipoprotein (LDL) receptor and the LDL receptor-related protein (LRP), functioning as the component of plasma lipoproteins in the transportation of lipids. Physiologically, ApoE is a multifunctional protein with central roles in lipid metabolism; it transports lipids, including cholesterol, through the cerebrospinal fluid (CSF) and plasma. ApoE expression regulation and apoE gene polymorphism have an important connection with neurological or neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), ischemic stroke, and other diseases.

Cognitive impairment in patients with multiple sclerosis: association with the APOE gene and promoter polymorphisms

Background Studies examining the ε4 allele of the APOE gene as a factor affecting the severity of multiple sclerosis (MS) have yielded conflicting results. The focus of these studies on physical disability to the neglect of cognitive impairment is surprising in light of the associations between the ε4 allele and other dementia conditions. Only two studies examine the relationship between the ε4 allele and cognitive impairment.

Methods A neuropsychological test battery was administered to 263 MS patients, and their current disability status was evaluated. Genotypes were determined for APOE epsilon and for two promoter region polymorphisms (-219 G/T and -491 A/T).

Results Although effects were generally weak, female patients with the -491 AA genotype had a later age of disease onset, lower disability scores, and somewhat higher scores on the cognitive battery. Male patients with the ε2 allele had lower disability and higher scores on the cognitive battery. The ε4 allele was not related to physical disability, and there was no difference between ε4+and ε4– patients in overall cognitive performance. However, when patients with severe cognitive impairment were identified, a greater proportion (52%) of these patients had the ε4 allele than those in the unimpaired group (27%).

Conclusion An association with the ε4 allele was evident in this study, but only in cases of severe cognitive impairment.

Impact of Pharmacotherapy on Cognitive Dysfunction in Patients with Multiple Sclerosis

Cognitive impairment is a common symptom of multiple sclerosis (MS), adversely impacting many spheres of daily functioning. Yet the effectiveness of pharmacological interventions for cognitive impairment in MS is unclear. Clinicians and patients alike would benefit from formal guidelines regarding effective management of cognitive symptoms. We reviewed the background on the measurement, pathophysiology and risk factors for cognitive dysfunction in MS, and then examined the published clinical trials of pharmacotherapy, including both disease-modifying treatments (DMTs) and symptom-management therapies (SMTs). Our review of DMTs revealed only a single well-designed, randomized, controlled trial where intramuscular interferon (IFN)-β1a, administered once weekly, was compared with placebo. The results showed significant benefits in terms of cognitive processing speed and memory. Less convincing but promising data have shown the potential benefits of IFN-β1b and natalizumab. The literature on SMTs is replete with placebo-controlled, single-centre studies, with a failure to replicate initially promising results. The results for SMTs such as acetylcholinesterase inhibitors and psychostimulants are mixed. Some encouraging data show promise but not to a threshold of indication for standard clinical use. Numerous methodological factors hamper research in this area. Acknowledging the lack of firm conclusions, we argue that all DMTs are likely to benefit cognition and that, if otherwise safe, SMTs with some empirical support may be attempted at the discretion of the treating clinician. We offer some guidance on the assessment and monitoring of cognitive function to inform off-license treatment of cognitive impairment in MS patients.

Role of apolipoprotein E in neurodegenerative diseases

Apolipoprotein E (APOE) is a lipid-transport protein abundantly expressed in most neurons in the central nervous system. APOE-dependent alterations of the endocytic pathway can affect different functions. APOE binds to cell-surface receptors to deliver lipids and to the hydrophobic amyloid-β peptide, regulating amyloid-β aggregations and clearances in the brain. Several APOE isoforms with major structural differences were discovered and shown to influence the brain lipid transport, glucose metabolism, neuronal signaling, neuroinflammation, and mitochondrial function. This review will summarize the updated research progress on APOE functions and its role in Alzheimer's disease, Parkinson's disease, cardiovascular diseases, multiple sclerosis, type 2 diabetes mellitus, Type III hyperlipoproteinemia, vascular dementia, and ischemic stroke. Understanding the mutations in APOE, their structural properties, and their isoforms is important to determine its role in various diseases and to advance the development of therapeutic strategies. Targeting APOE may be a potential approach for diagnosis, risk assessment, prevention, and treatment of various neurodegenerative and cardiovascular diseases in humans.

Interactions between the apolipoprotein E ε4 allele status and adverse childhood experiences on depressive symptoms in older adults

BACKGROUND

The influence of childhood adversity on depression is modulated by genetic vulnerability. The apolipoprotein E ε4 (APOE-ε4) allele is a strong genetic risk factor for Alzheimer's disease (AD). Because late-life depressive symptoms could be a part of the preclinical course of AD, the APOE-ε4 allele may contribute to depression in old age.

OBJECTIVE

The aim of this study was to evaluate whether an APOE-ε4 carrier status was associated with depressive symptoms in older adults and to detect the gene-environment interaction between APOE-ε4 status and childhood adversity in relation to depressive symptoms in old age.

METHOD

The participants consisted of 137 older adults (age range 50-70) without any psychiatric history or clinically significant cognitive impairment. APOE genotypes and measures of childhood adversity and depressive symptoms were obtained.

RESULTS

There was a significant positive association between adverse childhood experiences (ACE) scores and depressive symptoms (B=0.60; 95% CI=0.26, 0.93 for a 1 score increase in ACE scores; p=0.001). Although APOE-ε4 status per se was not associated with depressive symptoms, there was a significant interaction of the ACE scores with the APOE genotype in relation to depressive symptoms (B=0.78; 95% CI=0.02, 1.55; p=0.044). There was a significantly higher effect of childhood adversity on depressive symptoms in APOE-ε4 carriers than non-carriers (t=2.13, p=0.035).

CONCLUSIONS

Our results suggest that the APOE-ε4 may modulate the association between childhood adversity and depressive symptoms in older adults. However, more research in a larger sample is needed to gain a better understanding of the relationship between the APOE-ε4, childhood adversity, and depression.

Presenilin enhancer-2 gene: identification of a novel promoter mutation in a patient with early-onset familial Alzheimer's disease

γ-Secretase proteins complex cleaves the amyloid precursor protein (APP) to generate amyloid-β (Aβ) peptides. Considerable evidence suggests that alterations in genes encoding these proteins exert their influence on the pathogenesis of familial Alzheimer's disease (FAD). Presenilin enhancer-2 gene (PEN-2) is a necessary component of the γ-Secretase complex. Recently, it has been shown that PEN-2 mutations could be involved in Alzheimer's disease (AD). We performed a mutational screening of all PEN-2 coding and promoter regions in a FAD cohort derived from Southern Italy. Four hundred and fifty-two subjects (FAD: 97;

CONTROLS

355) were recruited for this study. We identified for the first time in a key region necessary for the promoter activity a novel 3 bp deletion in a subject with early-FAD. Our genetic data demonstrate that the mutant allele may influence the transcriptional activity of the PEN-2 gene. Although the effective role of the PEN-2 promoter deletion in AD is not entirely clear, these findings might lead to more studies on its functional and genetic role.

Multiple sclerosis and cognitive decline: is ApoE-4 a surrogate marker?

BACKGROUND - The role of the apolipoprotein E (ApoE) polymorphism has been well demonstrated in neurodegenerative disorders such as Alzheimer. However, its role in multiple sclerosis (MS) remains unclear. AIMS - The aims of our study were as follows: (i) to assess whether ApoE-4 might be a surrogate marker of cognitive decline in MS; (ii) to confirm the presence of cognitive impairment in mildly disabled patients treated with interferon-beta; and (iii) to analyse the correlation between cognitive disturbances and clinical variables. MATERIAL AND METHODS -  Fifty relapsing-remitting MS patients underwent a battery of neuropsychological tests and were genotyped for ApoE. Their scores were compared with those of 35 controls. RESULTS - No association was found between ApoE-4 and cognitive impairment. Significant differences in most domains were observed between MS and the control group. Cognitive decline was not related to disability progression. CONCLUSION - No association between cognitive impairment and ApoE-4 or clinical markers was detected in our MS patients.

Risk factors for and management of cognitive dysfunction in multiple sclerosis

Cognitive impairment is common in multiple sclerosis (MS), especially when assessed by neuropsychological tests that emphasize mental processing speed, episodic memory, and some aspects of executive function. In this Review, we question why some MS patients develop severe impairment in cognitive abilities, while cognitive ability remains intact in others. We find that the heterogeneity in neuropsychological presentation among patients with MS reflects the influence of many factors, including genetics, sex, intelligence, disease course, comorbid neuropsychiatric illness, and health behaviors. Neuropsychological deficits are also robustly correlated with brain MRI metrics. Male patients with early evidence of cerebral gray matter atrophy are most prone to impairment, whereas high premorbid intelligence improves the neuropsychological prognosis. Routine evaluation of cognition is useful for helping patients to navigate problems related to activities of daily living and work disability and, if reliable methods are employed, cognitive decline can be detected and included among the many clinical signs of disease progression or treatment failure. Pharmacological treatments for neuropsychological impairment are on the horizon, although presently no firm medical indications exist for the condition.

Gender issues in multiple sclerosis: an update

Although multiple sclerosis (MS) affects both women and men, women are more susceptible to MS than men. Accumulating evidence indicates that the incidence and prevalence of MS is increasing, more so in women than in men. Owing to pregnancy, differing hormonal states and distinct social roles, the impact of MS differs between women and men. Since Patricia K Coyle published a review on gender issues in MS, multiple studies have added to the body of knowledge. This update will summarize the current thinking on gender-related issues in MS and we will address incidence and prevalence, hormonal factors, pregnancy and breastfeeding, genetics, course and prognosis, imaging, treatment and psychosocial aspects. Future progression within this field will help elucidate the cause of and define the treatment of MS.

APOE epsilon4 and the cognitive genetics of multiple sclerosis

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

ApoE alleles, depression and positive affect in multiple sclerosis

BACKGROUND

The role of apolipoprotein E (ApoE) alleles has received recent attention in depressive disorders, the ApoE epsilon4 conferring greater risk for poorer outcomes, and the ApoE epsilon2 allele providing some protective effects. Depression is common in multiple sclerosis (MS) and the role of ApoE alleles is unknown.

AIMS

To evaluate ApoE alleles in relation to symptoms of depression in a cohort of patients with MS participating in the Sonya Slifka Longitudinal Multiple Sclerosis Study (Slifka Study). To examine risk and protection, depressed mood and positive affect were each investigated with respect to the ApoE epsilon4 and ApoE epsilon2 alleles, respectively.

RESULTS

Of the total 101 participants, 22.8% were ApoE epsilon2 carriers and 21.8% were ApoE epsilon4 carriers. Hierarchical linear regression analyses suggested that after controlling for demographics, disease duration, and disability, ApoE epsilon2 significantly predicted increased positive affect (R2Delta=0.05, F(1,94)=5.44, P=0.02) and was associated with decreased severity of depressive symptoms, although this did not reach statistical significance (R2Delta=0.03, F(1,94)=3.44, P=0.06). ApoE epsilon4 did not significantly predict depression status.

CONCLUSION

The presence of the ApoE epsilon2 allele in this study is suggested to be protective against depressive symptoms in our subsample of patients recruited from the Slifka Study. These findings are consistent with reports in psychiatric populations linking ApoE epsilon2 with decreased incidence of depressive disorders. Further investigation would be warranted to understand the role of ApoE genotypes and risk for depressive symptoms.

An APOA1 promoter polymorphism is associated with cognitive performance in patients with multiple sclerosis

BACKGROUND

Elevated ApoA1 levels have been associated with decreased dementia risk. The A-allele of the APOA1 -75G/A promoter polymorphism has been associated with elevated ApoA1 levels.

OBJECTIVE

We sought to investigate the effect of the APOA1 -75G/A promoter polymorphism on cognitive performance in patients with multiple sclerosis (MS).

METHODS

A total of 138 patients with MS and 43 controls were studied and underwent neuropsychological assessment with Rao's Brief Repeatable Battery and the Stroop test. All patients were genotyped for APOA1.

RESULTS

APOA1 A-allele carriers displayed superior overall cognitive performance compared with non-carriers (P 0.008) and had a three-fold decrease in the relative risk of overall cognitive impairment (OR 0.29, 95% CI 0.11-0.74). Regarding performance on individual cognitive domains, although APOA1 A-allele carriers performed better than non-carriers on all tests, this was significant only for semantic verbal fluency and the Stroop interference task (P 0.036 and 0.018, respectively).

CONCLUSIONS

We found an association of the APOA1 -75G/A promoter polymorphism with cognitive performance in MS. This effect was most prominent on semantic verbal fluency and the Stroop interference task.

Selective Decline in Information Processing in Subgroups of Multiple Sclerosis: An 8-Year Longitudinal Study

Multiple sclerosis (MS) is an inflammatory and degenerative disease of the central nervous system (CNS) that causes white matter and cortical lesions over many years. The CNS is selectively affected by the disease with a great variety of symptoms between patients. In this study, we describe the impact on various aspects of cognition over an 8-year follow-up period in 31 consecutive MS patients subgrouped as relapsing remitting (RR) MS, secondary progressive (SP) MS, and primary progressive (PP) MS. Results showed a differential pattern of cognitive decline already at baseline in speed of information processing. During the follow-up, a pronounced decline occurred in speed of information processing, finger-motor speed, copying geometrical designs, episodic memory, and visuospatial short-term memory. A striking difference was observed between a marked decline in visual reaction time, whereas no significant change was seen in auditory reaction time. In contrast, there was no time-related decline in verbal abilities. However, an initial marked cognitive impairment predicted further cognitive decline over the 8-year follow-up. Information-processing tests were found to be an especially strong predictor of long-term cognitive decline. In addition, high EDSS score at follow-up was associated with decline in information processes. Results also showed that SP-MS patients deteriorated significantly more than the other two groups, particularly in visual compared to auditory information processing. To conclude, cognitive decline appeared particularly in SP-MS patients and in visual information processing.

The association between apolipoprotein E and multiple sclerosis

The article is a complete literature study that investigates the association between apolipoprotein E (Apo E) and multiple sclerosis (MS). Apo E is an important factor in transport, uptake, and redistribution of cholesterol, which is significant to remodelling and repair of nerve tissue. Apo E is involved in neurodegenerative diseases and the most well known association is between Apo epsilon4 and Alzheimer's disease. Only one study found that homozygosity for Apo epsilon4 does cause an increased risk of developing MS. No results indicate that heterozygosity for Apo epsilon4 causes a greater risk of developing MS. No association between the Apo epsilon4 allele and MS subgroups, age of onset, and gender has been found. The association between Apo epsilon4 and relapse rate is contradictory. Most results confirm the hypothesis about an association between the Apo epsilon4 allele and increased disease progression. Two longitudinal studies found an association between Apo epsilon4 and increased disease progression. Half of the cross-sectional studies found the same association. Four of seven published studies examining the association between Apo epsilon4 and increased disease progression using magnetic resonance imaging (MRI) found a significant association. Apo epsilon4 appears to be a predisposing factor to a faster disease progression in MS.

Assessment of cognitive dysfunction in multiple sclerosis

Cognitive deficit can be an early feature in the course of multiple sclerosis, may occur clinically isolated, impacts on social activities and could reflect disease progression that is independent of physical disability with potential therapeutical consequences. Neuropsychological tests should be independent of motor coordination or visuo-spatial ability, but sensitive to subtle cognitive changes, exploring attention speed and working memory They could be included in brief batteries with good normative data and alternative forms for future therapeutic trials. We recommend for a brief battery of neuropsychological tests the inclusion of PASAT and two memory tests: the learning stage of CVLT and backward Digit Span with a total time duration of 30 min. A complementary tool could be a cognitive questionnaire for informant. After a relapse, cognitive assessment should be performed at least 8 weeks afterwards. If the patient presents with psychiatric symptoms, a specific assessment should be proposed before starting a complete cognitive assessment. Finally, we propose some red flags warranting neuropsychological screening: patients with a mild physical disability, but unable to maintain their professional activities, pathological laughing-crying, increased age and low educational level.

De la psychométrie au handicap neuropsychologique dans la sclérose en plaques. Proposition d’une batterie de dépistage en langue française et facteurs de risque cognitifs

INTRODUCTION

Cognitive deficit in multiple sclerosis (MS) is a frequent early feature in the disease course, which conditions patients' overall disability. The goals of this study were to validate a reproducible brief screening battery written in French and to examine cognitive risk profiles in patients with a mild physical disability.

METHODS

Cognitive performances of 40 patients with EDSS <4.5 were compared with those of a control group. The study was completed with an analysis of socio-demographic, clinical and psychological variables (questionnaires).

RESULTS

Three tests were discriminative with satisfactory predictive values (positive: 88 percent; negative: 96 percent) and a time duration <30 minutes: PASAT (hard condition), backward digit span, learning stage of California Verbal Learning Test. Four variables were associated with cognitive deficit: educational level <11 years, age >40 years, pathological laughing-crying, unemployment.

CONCLUSIONS

Our brief battery is an easy and reproducible tool. Completed with warning signs indicating the need for neuropsychological screening, this tool provides the practitioner with a global means of assessing disease activity and potentially therapeutic efficacy.

Neuropsychological assessment, quantitative MRI and ApoE gene polymorphisms in a series of MS patients treated with IFN beta-1b

Few trials issued the effect of disease-modifying medications on cognitive functions in multiple sclerosis. We designed an open-label longitudinal study to evaluate, during 2 years, cognitive performance and its relationship with MRI data and ApoE polymorphism findings in a group of relapsing-remitting (RR) multiple sclerosis (MS) Interferon (IFN) beta-1b-treated patients (median age 30 years, median disease duration 3.4 years). Complete neuropsychological battery was grouped into attention, information learning/memory, language and visuo-spatial functions. Fifty-two patients (33 females) were enrolled in the study. Six patients (11.5%) dropped out, mainly due to side effects. At baseline neuropsychological evaluation, we found 54% normal, 42% mildly impaired and 4% moderately impaired patients. At 2 years follow-up, cognitive status was stable in 65%, improved in 33% and worsened in 2% of patients. No significant relations were found between global cognitive outcome vs. EDSS change, clinical disease activity, MRI data or ApoE gene polymorphisms over the 2 years follow-up. EDSS and MRI fractional volumes were found to correlate with the performance at single tests. Twenty-one patients (45.6%) showed active MRI scans throughout the study, without any worsening at the corresponding neuropsychological examination. This ongoing trial suggests a possible beneficial effect of IFN beta-1b treatment on cognitive functions in RRMS patients. Extension of follow-up and further data analyses are needed to confirm and clarify these findings.

Verbal fluency deficits in multiple sclerosis

A quantitative review of 35 studies with 3673 participants was conducted to estimate and compare the magnitude of deficits upon tests of phonemic and semantic fluency for participants with multiple sclerosis (MS) relative to healthy controls. Participants with MS were substantially but similarly impaired on tests of phonemic and semantic fluency. These deficits were larger than deficits on measures of verbal intelligence, confrontation naming and another widely used measure of executive functioning, the Wisconsin Card Sorting Test, but were of a comparable or smaller magnitude relative to deficits on the oral version of the Symbol Digit Modalities Test (SDMT). This is consistent with other research suggesting that measures of verbal fluency and the SDMT may be amongst the most sensitive neuropsychological measures to cognitive impairment in MS. Increased neurological disability and a chronic progressive (as opposed to a relapsing remitting) disease course were associated with larger deficits on tests of phonemic and semantic fluency. However, it is suggested that this latter finding is attributable to the distinct clinical features of chronic progressive and relapsing remitting sub-types. Thus, patients who follow a chronic progressive course tend to be older, have an increased duration of illness and experience greater neurological disability. Once these variables were controlled for, differences between the two sub-types were substantially attenuated.

Apo E in multiple sclerosis and optic neuritis: the apo E-epsilon4 allele is associated with progression of multiple sclerosis

OBJECTIVE

To investigate the association between apolipoprotein E (Apo E) genotype in multiple sclerosis (MS) and acute monosymptomatic optic neuritis (ON) in a genetically homogeneous population with a high frequency of the Apo epsilon4 allele.

BACKGROUND

The association between heterozygosity of Apo epsilon4 and the development of MS is thoroughly investigated, while the association between homozygosity of Apo epsilon4 and the development of MS is insufficiently studied. The association between Apo E genotype and disease progression remains controversial.

METHODS

475 patients were included, 385 with MS and 90 with ON, consecutively seen in the MS clinic in the County of Copenhagen. Clinical data were obtained from medical records and degree of disability was determined prospectively using the Kurtzke expanded disability status scale (EDSS). Blood samples were used for Apo E genotyping. Disease progression was evaluated by the progression index (PI = EDSS/disease duration). Apo E genotype distribution was compared with 361 healthy controls.

RESULTS

The Apo epsilon genotype distribution in the MS and ON groups was similar to the controls. The rate of disease progression in the group of MS patients with a disease duration of 10 years or less was significantly faster in the Apo epsilon4 positive group (heterozygosity and homozygosity for Apo epsilon4) (PI = 1.41) compared to the Apo epsilon4 negative group (PI =0.92) (P =0.009). Observing the MS subgroups, we found that the group of patients with RRMS had a faster rate of disease progression in the Apo epsilon4 positive group (PI =1.12) compared to the Apo epsilon4 negative group (P =0.77) (P =0.024).

CONCLUSIONS

Apo E genotypes do not influence the development of MS and ON. The Apo epsilon4 allele seems to predispose carriers with MS to a faster progression of disease.

Gender-related effect of clinical and genetic variables on the cognitive impairment in multiple sclerosis

BACKGROUND

Cognitive impairment may occur at any time during the course of multiple sclerosis (MS), and it is often a major cause of disability in patients with the disease. The APOE-epsilon4 allele is the major known genetic risk factor for late onset familial and sporadic Alzheimer's Disease (AD), and it seems to be implicated in cognitive decline in normal elderly persons.

OBJECTIVE

To investigate the clinical and genetic variables that can be associated with the cognitive decline in patients with MS.

METHODS

Five-hundred and three patients with clinically definite MS underwent a battery of neuropsychological tests and, according to the number of failed tests, were divided into cognitively normal and impaired. All patients were genotyped for APOE gene polymorphisms.

RESULTS

Fifty-six percent of MS patients showed, to different extents, cognitive impairment. Cognitive decline was predominant in men and was associated with disease duration, Kurtzke Expanded Disability Status Scale (EDSS) score, a low level of education, and, interestingly, the epsilon4 allele of the APOE gene. By contrast, cognitive impairment in women was independent of any investigated variable.

CONCLUSION

The findings demonstrate that clinical and genetic factors play a role in men affected by MS developing cognitive impairment.

No major association of ApoE genotype with disease characteristics and MRI findings in multiple sclerosis

BACKGROUND

Whereas a number of studies suggest that the ApoE polymorphism is not associated with disease susceptibility in multiple sclerosis (MS), results with regard to disease severity, however, are conflicting. Some studies suggest an unfavourable role of the epsilon4 allele. This study was performed to assess the association of the ApoE polymorphism with both disease susceptibility and disease course in a large group of MS patients using clinical and MRI measures. In addition the data were combined with available data from the literature.

METHODS

In a group of 408 patients with clinically definite MS, genotype distribution was compared with that of 144 healthy controls. Combined analysis of published data on the association of ApoE polymorphism with MS was performed. Demographic and clinical findings were recorded and related to the ApoE genotype. In a subgroup, longitudinal MRI findings were available and related to the ApoE genotype.

RESULTS

No significant differences were found in the distribution of genotypes between MS patients and controls. Combined analysis of published data showed a slightly increased susceptibility for MS in epsilon2-carriers. Disease characteristics (including age at onset and onset type), disease severity (progression index, time to reach EDSS 6) and MRI findings (lesion volumes and atrophy measures) were not associated with carriership o epsilon2 or epsilon4.

CONCLUSIONS

In this cohort no association of the ApoE genotype with disease susceptibility nor clinical and MRI measures could be identified. However, combined analysis of published data could not definitely exclude the possibility of a minor role for epsilon2-carriership in MS.

Genotypes at the APOE and SCA2 loci do not predict the course of multiple sclerosis in patients of Portuguese origin

Multiple sclerosis (MS) is a demyelinating disease that affects about one in 500 young Europeans. In order to test the previously proposed influence of the APOE and SCA2 loci on susceptibility to MS, we studied these loci in 243 Portuguese patients and 192 healthy controls and both parents of 92 patients. We did not detect any significant difference when APOE and SCA2 allele frequencies of cases and controls were compared, or when we compared cases with different forms of the disease. Disequilibrium of transmission was tested for both loci in the 92 trios, and we did not observe segregation distortion. To test the influence of the APOE epsilon4 and SCA2 22 CAGs alleles on severity of disease, we compared age at onset and progression rate between groups with and without those alleles. We did not observe an association of the epsilon4 or the 22 CAGs alleles with rate of progression in our total patient population; allele epsilon4 was associated with increased rate of progression of MS in a subset of patients with less than 10 years of the disease. However, globally in the Portuguese population, the APOE and SCA2 genes do not seem to be useful in the clinical context as prognostic markers of this disorder.

Detection of apolipoprotein E phenotype in unconcentrated cerebrospinal fluid

We developed a simple method to detect apolipoprotein E (Apo E) polymorphism distribution in approximately 20 microL of unconcentrated cerebrospinal fluid (CSF). A combination of isoelectric focusing in 3 M urea gel and immunoblotting was employed. Apo E phenotypes were identified in CSF samples from 45 patients with probable Alzheimer disease (AD), 15 with multiple sclerosis (MS), and 25 with other neurological diseases (OND). When the data were compared with a set of matched plasma samples, the results were identical. The method is useful for Apo E phenotyping from fresh or frozen unconcentrated CSF, when blood or plasma is not available.

Genetics of multiple sclerosis: linkage and association studies

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system caused by an interplay of environmental and genetic factors. The only genetic region that has been clearly demonstrated by linkage and association studies to contribute to MS genetic susceptibility is the human leukocyte antigen (HLA) system. The majority of HLA population studies in MS have focused on Caucasians of Northern European descent, where the predisposition to disease has been consistently associated with the class II DRB1*1501-DQA1*0102-DQB1*0602 haplotype. A positive association with DR4 was detected in Sardinians and in other Mediterranean populations. Moreover DR1, DR7, DR11 have been found to be protective in several populations. Systematic searches aimed at identifying non-HLA susceptibility genes were undertaken in several populations by means of linkage studies with microsatellite markers distributed across the whole genome. The conclusion of these studies was that there is no major MS locus, and genetic susceptibility to the disease is most likely explained by the presence of different genes each conferring a small contribution to the overall familial aggregation. The involvement of several candidate genes was tested by association studies, utilizing either a population-based (case control) or a family-based (transmission disequilibrium test) approach. Candidate genes were selected mainly on the basis of their involvement in the autoimmune pathogenesis and include immunorelevant molecules such as cytokines, cytokine receptors, immunoglobulin, T cell receptor subunits and myelin antigens. With the notable exception of HLA, association studies met only modest success. This failure may result from the small size of the tested samples and the small number of markers considered for each gene. New tools for large scale screening are needed to identify genetic determinants with a low phenotypic effect. Large collaborative studies are planned to screen several thousands of patients with MS with several thousands of genetic markers. The tests are increasingly based on the DNA pooling procedure.

APOE genotypes and disease severity in multiple sclerosis

Apolipoprotein E (opoE) is involved in the transport of lipids necessary for membrane repair and is encoded by a gene on chromosome 19q13, a region positive for linkage in two multiple sclerosis (MS) genome-wide screens. The APOE epsilon4 allele confers susceptibility to both familial and sporadic Alzheimer's disease (AD). Carriage of epsilon4 is associated with defective dendritic remodeling in AD, and with unfavorable clinical outcome in head trauma and cerebrovascular disease. According to the results of previous studies, APOE epsilon4 does not increase the risk of developing MS, but it may influence disease progression and ultimate disability. From a total cohort of over 900 MS patients, we compared APOE epsilon2-4 genotypes in, roughly, the cohort's least disabled and most disabled septiles. 'Benign MS' (n=124) was defined as an Expanded Disability Status Scale (EDSS) score of 3.0 or less, despite at least 10 years of disease duration, and 'severe MS' (n=140) as the attainment of an EDSS score of 6.0 within 8 years of disease onset. We found no significant differences in genotype or phenotype frequencies between the benign-MS and severe-MS septiles; however, the risk conferred by epsilon4 rose progressively upon comparison of carriage rates in more narrowly defined anti-podal quantiles.

Interferon-beta-1b and interferon-gamma have similar inhibitory effects on apolipoprotein-E production in the monocyte/macrophage

Apolipoprotein-E (Apo-E) is the major lipid carrier in the brain, and is therefore important in the recyding of lipids and cholesterol to regenerating neurons during the remission phase of multiple sclerosis (MS). Interferon (IFN)-gamma has been shown to inhibit Apo-E production by a mainly post-transcriptional method in a macrophage cell line, and reduced Apo-E in cerebrospinal fluid is noted during the remission phase in patients. IFN-beta-1b is a recombinantly produced, anti-inflammatory cytokine, which has been shown to reduce the severity of MS relapses and reduce relapse rate. We have examined the effects of IFN-gamma and IFN-beta-1b on the production of Apo-E mRNA, cellular protein and secreted protein in primary monocytes derived from donor blood. IFN-beta-1b does not relieve the dose-dependent inhibition of Apo-E seen with IFN-gamma at up to 100 U/ml in these cells, and when used alone inhibits Apo-E production in a dose-dependent manner. This inhibition by IFN-beta-1b was seen to be at a transcriptional level, and dose dependent up to 100 U/ml. Apo-E genotype, which has also been linked to failure to recover from MS relapses, did not affect this inhibition. The mode of action of IFN-beta-1b in MS is therefore not thought to be through modification of Apo-E production.

Association of polymorphisms in the apolipoprotein E region with susceptibility to and progression of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system, with a complex etiology that includes a strong genetic component. The contribution of the major histocompatibility complex (MHC) has been established in numerous genetic linkage and association studies. In addition to the MHC, the chromosome 19q13 region surrounding the apolipoprotein E (APOE) gene has shown consistent evidence of involvement in MS when family-based analyses were conducted. Furthermore, several clinical reports have suggested that the APOE-4 allele may be associated with more-severe disease and faster progression of disability. To thoroughly examine the role of APOE in MS, we genotyped its functional alleles, as well as seven single-nucleotide polymorphisms (SNPs) located primarily within 13 kb of APOE, in a data set of 398 families. Using family-based association analysis, we found statistically significant evidence that an SNP haplotype near APOE is associated with MS susceptibility (P=.005). An analysis of disease progression in 614 patients with MS from 379 families indicated that APOE-4 carriers are more likely to be affected with severe disease (P=.03), whereas a higher proportion of APOE-2 carriers exhibit a mild disease course (P=.02).

Cognitive impairments in multiple sclerosis: a review

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Cognitive impairment (CI) may develop at any time during the course of the disease in the presence or absence of neurological disability. On the basis of comprehensive neuropsychological studies, there is now a consensus among investigators that 45 percent to 65 percent of MS patients suffer from some degree and form of cognitive difficulty. Features of CI include bradyphrenia; impaired attention, concentration and abstract reasoning; reduced manual speed and dexterity; deficits in memory retrieval; and language deficits in both the relapsing-remitting and progressive forms of MS. Impairments in all cognitive domains may result from the diffuse spread of microscopic pathology, although a preferential lobar distribution of plaques can present with a predominant deficit in the corresponding cognitive function. Nevertheless, the severity of CI best correlates with total microscopic and macroscopic disease burden of the brain as defined by recently developed magnetic resonance imaging (MRI) sequences. A disruption of connecting intercortical and subcortical pathways is likely to be the main cause of metabolic and functional abnormalities in neurons. However a direct toxic effect of soluble inflammatory products may also compromise neuronal function and survival. Early treatment of MS with interferons and copaxone can prevent or delay the onset of both neurological and cognitive disabilities by reducing the inflammatory activity and damage in the CNS. Until more powerful neuroprotective agents become available, simple neuropsychological screening and cognitive rehabilitation for memory and language impairments will remain important components in the care of MS patients.

Susceptibility to multiple sclerosis: interplay between genes and environment

Multiple sclerosis is a complex trait of unknown etiology. Epidemiological data have shown that susceptibility to multiple sclerosis is determined by both genetic and environmental factors. It is unknown whether the clinical subcategories of multiple sclerosis are separate diseases with separate etiologies and causes. Recent theories of the pathogenesis of multiple sclerosis and candidate genes are discussed. Other potential nonchromosomal factors involved in multiple sclerosis susceptibility such as mitochondrial DNA and viral factors such as Chlamydia pneumoniae are reviewed.