Preservation of gray matter volume in multiple sclerosis patients with the Met allele of the rs6265 (Val66Met) SNP of brain-derived neurotrophic factor

Iron deposition on SWI-filtered phase in the subcortical deep gray matter of patients with clinically isolated syndrome may precede structure-specific atrophy

BACKGROUND AND PURPOSE

Increasing evidence suggests that iron deposition is present in the later stages of MS. In this study we examined abnormal phase values, indicative of increased iron content on SWI-filtered phase images of the SDGM in CIS patients and HC. We also examined the association of abnormal phase with conventional MR imaging outcomes at first clinical onset.

MATERIALS AND METHODS

Forty-two patients with CIS (31 female, 11 male) and 65 age and sex-matched HC (41 female, 24 male) were scanned on a 3T scanner. Mean age was 40.1 (SD = 10.4) years in patients with CIS, and 42.8 (SD = 14) years in HC, while mean disease duration was 1.2 years (SD = 1.3) in patients with CIS. MP-APT, NPTV, and normalized volume measurements were derived for all SDGM structures. Parametric and nonparametric group-wise comparisons were performed, and associations were determined with other MR imaging metrics.

RESULTS

Patients with CIS had significantly increased MP-APT (P = .029) and MP-APT volume (P = .045) in the pulvinar nucleus of the thalamus compared with HC. Furthermore, the putamen (P = .004), caudate (P = .035), and total SDGM (P = .048) displayed significant increases in MP-APT volume, while MP-APT was also significantly increased in the putamen (P = .029). No global or regional volumetric MR imaging differences were found between the study groups. Significant correlations were observed between increased MP-APT volumes of total SDGM, caudate, thalamus, hippocampus, and substantia nigra with white matter atrophy and increased T2 lesion volume (P < .05).

CONCLUSION

Patients with CIS showed significantly increased content and volume of iron, as determined by abnormal SWI-phase measurement, in the various SDGM structures, suggesting that iron deposition may precede structure-specific atrophy.

Brain-derived neurotrophic factor (BDNF) gene: a gender-specific role in cognitive function during normal cognitive aging of the MEMO-Study?

Cognitive aging processes are underpinned by multiple processes including genetic factors. The brain-derived neurotrophic factor (BDNF) has been suggested to be involved in age-related cognitive decline in otherwise healthy individuals. The gender-specific role of the BDNF gene in cognitive aging remains unclear. The identification of genetic biomarkers might be a useful approach to identify individuals at risk of cognitive decline during healthy aging processes. The aim of this study was to investigate the associations between three single-nucleotide polymorphisms (SNPs) in the BDNF gene and domains of cognitive functioning in normal cognitive aging. The sample, comprising 369 participants (M = 72.7 years, SD = 4.45 years), completed an extensive neuropsychological test battery measuring memory, motor function, and perceptual speed. The relationships between the SNPs rs6265, rs7103411, and rs7124442 and cognitive domains were examined. While significant main effects of BDNF SNPs on cognitive function were found for the association between rs7103411 and memory performance, gender-specific analyses revealed for females significant main effects of rs7103411 for memory and of rs6265 for perceptual speed independent of the APOE*E4 status and education. The finding for the association between rs6265 and perceptual speed in females remained significant after Bonferroni correction for multiple comparisons. None of the analyses showed significant results for males. This study is the first to implicate that the SNPs rs6265 and rs7103411 affect cognitive function in the elderly in a gender-specific way.

No association between conventional brain MR imaging and chronic cerebrospinal venous insufficiency in multiple sclerosis

BACKGROUND AND PURPOSE

CCSVI has been reported to occur at high frequency in MS. Its significance in relation to MR imaging parameters also needs to be determined, both in patients with MS and HCs. Therefore, this study determined the associations of CCSVI and conventional MR imaging outcomes in patients with MS and in HCs.

MATERIALS AND METHODS

T2, T1, and gadolinium lesion number, LV, and brain atrophy were assessed on 3T MR imaging in 301 subjects, of whom 162 had RRMS, 66 had secondary-progressive MS subtype, and 73 were HCs. CCSVI was assessed using extracranial and transcranial Doppler evaluation. The MR imaging measure differences were explored with 27 borderline cases for CCSVI, added to both the negative and positive CCSVI groups to assess sensitivity of the results of these cases.

RESULTS

No significant differences between subjects with and without CCSVI were found in any of the individual diagnostic subgroups or MS disease subtypes for lesion burden and atrophy measures, independently of the CCSVI classification criteria used, except for a trend for higher T2 lesion number (irrespective of how borderline cases were classified) and lower brain volume (when borderline cases were included in the positive group) in patients with RRMS with CCSVI. No CCSVI or MR imaging differences were found between 26 HCs with, or 47 without, a familial relationship.

CONCLUSIONS

CCSVI is not associated with more severe lesion burden or brain atrophy in patients with MS or in HCs.

Iron deposition in multiple sclerosis lesions measured by susceptibility-weighted imaging filtered phase: a case control study

PURPOSE

To investigate phase lesions identified on susceptibility-weighted imaging (SWI)-filtered phase images in patients with multiple sclerosis (MS), clinically isolated syndrome (CIS) and healthy controls (HC). To relate phase lesion characteristics to other clinical and MRI outcomes.

MATERIALS AND METHODS

95 relapsing-remitting (RR), 40 secondary-progressive (SP) MS patients, as well as 19 CIS patients and 49 age- and sex-matched HC, were scanned on a 3T scanner. Phase-, T1-, and T2-lesion characteristics were determined. Overlap of T1- and T2-weighted imaging (WI) lesions with phase lesions (T1P and T2P), as well as brain atrophy outcomes, was assessed.

RESULTS

MS patients showed significantly greater numbers and larger volume of phase lesions, compared with HC (P < 0.001). 23.6% of T2 lesions overlapped with phase lesions, whereas the same figure for T1 lesions was 37.3%. Conversely, 33.4% and 69.7% of phase lesions were not visible on T2- or T1-WI, respectively. Phase, T1P and T2P lesions were not related to clinical outcomes, but phase lesions were related to ventricular enlargement.

CONCLUSION

Phase lesions were present in both MS and CIS patients, and showed partial overlap with lesions observed using conventional MRI. The role of phase lesions in clinical progression remains unclear and should be further explored.

Associations of moderate alcohol consumption with clinical and MRI measures in multiple sclerosis

OBJECTIVE

To examine the associations of alcohol consumption patterns with disability and brain injury in multiple sclerosis (MS) patients.

DESIGN

This study included 423 subjects (272 MS patients, 151 healthy controls) participating in a study of clinical, environmental and genetic risk factors in MS. Disability was assessed with the Expanded Disability Status Scale (EDSS) and the MS Severity Scale (MSSS). Brain injury was assessed using the quantitative MRI measures of T2-lesion volume (T2-LV), T1-LV, normalized volumes of brain parenchyma (NBV), gray matter (NGMV) and lateral ventricle (NLVV). Information related to alcohol-consumption patterns was obtained with standardized questionnaire during an in-person interview. The associations of alcohol consumption variables with disability and MRI measures were assessed in regression analyses.

RESULTS

The frequency of MS patients who did not consume alcohol after MS (19.4%) was higher than the frequency before MS (p<0.001). The EDSS, NGMV and NLVV exhibited a non-linear dependence on duration of alcohol consumption after MS onset: non-linear regression analyses indicated that EDSS and NLVV were lower and the NGMV was greater in MS patients who had consumed for a period of 15years or less after MS onset compared those who did not consume alcohol or consumed it for more than 15years.

CONCLUSION

The duration of alcohol consumption is associated with disability and MRI measures in MS. Prospective, longitudinal studies of the role of alcohol in MS disease progression are warranted.

Information processing speed, neural efficiency, and working memory performance in multiple sclerosis: differential relationships with structural magnetic resonance imaging

Multiple sclerosis (MS), a central nervous system (CNS) neurodegenerative disorder, involves lesions of both white and gray matter and reported cognitive impairments that include processing speed (PS), executive function, and working memory (WM). This study closely examined the specifics of these cognitive deficits and their relationship to structural brain damage. A visual n-back task with 3 WM load conditions was used to assess WM performance (task accuracy), PS (reaction time, RT), and a novel measure of processing efficiency (standard deviation of RT, RTSD) in MS patients and controls. These behavioral measures were related to quantitative magnetic resonance imaging (MRI) measures of white and gray matter integrity. Even when MS patients performed as well as controls, as seen for low WM load (0-back), they responded more slowly and were less efficient in their speed of responding. Accuracy findings indicated that the correct match trials were superior to correct nonmatch trials at differentiating MS patients from controls. Further, decreased accuracy during the highest WM load condition was associated with global damage that included both gray and white matter atrophy, while slowed PS and particularly processing inefficiency were associated primarily with white matter atrophy in MS. Importantly, relationships between PS, processing efficiency, performance accuracy, and structural MRI measures were seen only during the highest WM load condition, the condition that required the most executive control. These findings suggest that the MRI/behavioral relationships that were present exclusively during the 2-back condition may reflect connectivity involving frontal cortical systems, the site for executive control.

Basal ganglia, thalamus and neocortical atrophy predicting slowed cognitive processing in multiple sclerosis

Information-processing speed (IPS) slowing is a primary cognitive deficit in multiple sclerosis (MS). Basal ganglia, thalamus and neocortex are thought to have a key role for efficient information-processing, yet the specific relative contribution of these structures for MS-related IPS impairment is poorly understood. To determine if basal ganglia and thalamus atrophy independently contribute to visual and auditory IPS impairment in MS, after controlling for the influence of neocortical volume, we enrolled 86 consecutive MS patients and 25 normal controls undergoing 3T brain MRI and neuropsychological testing. Using Sienax and FIRST software, neocortical and deep gray matter (DGM) volumes were calculated. Neuropsychological testing contributed measures of auditory and visual IPS using the Paced Auditory Serial Addition Test (PASAT) and the Symbol Digit Modalities Test (SDMT), respectively. MS patients exhibited significantly slower IPS relative to controls and showed reduction in neocortex, caudate, putamen, globus pallidus, thalamus and nucleus accumbens volume. SDMT and PASAT were significantly correlated with all DGM regions. These effects were mitigated by controlling for the effects of neocortical volume, but all DGM volumes remained significantly correlated with SDMT, putamen (r = 0.409, p < 0.001) and thalamus (r = 0.362, p < 0.001) having the strongest effects, whereas for PASAT, the correlation was significant for putamen (r = 0.313, p < 0.01) but not for thalamus. We confirm the significant role of thalamus atrophy in MS-related IPS slowing and find that putamen atrophy is also a significant contributor to this disorder. These DGM structures have independent, significant roles, after controlling for the influence of neocortex atrophy.

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.

Hypoperfusion of brain parenchyma is associated with the severity of chronic cerebrospinal venous insufficiency in patients with multiple sclerosis: a cross-sectional preliminary report

BACKGROUND

Several studies have reported hypoperfusion of the brain parenchyma in multiple sclerosis (MS) patients. We hypothesized a possible relationship between abnormal perfusion in MS and hampered venous outflow at the extracranial level, a condition possibly associated with MS and known as chronic cerebrospinal venous insufficiency (CCSVI).

METHODS

We investigated the relationship between CCSVI and cerebral perfusion in 16 CCSVI MS patients and 8 age- and sex-matched healthy controls. Subjects were scanned in a 3-T scanner using dynamic susceptibility, contrast-enhanced, perfusion-weighted imaging. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were measured in the gray matter (GM), white matter (WM) and the subcortical GM (SGM). The severity of CCSVI was assessed according to the venous hemodynamic insufficiency severity score (VHISS) on the basis of the number of venous segments exhibiting flow abnormalities.

RESULTS

There was a significant association between increased VHISS and decreased CBF in the majority of examined regions of the brain parenchyma in MS patients. The most robust correlations were observed for GM and WM (r = -0.70 to -0.71, P < 0.002 and P corrected = 0.022), and for the putamen, thalamus, pulvinar nucleus of thalamus, globus pallidus and hippocampus (r = -0.59 to -0.71, P < 0.01 and P corrected < 0.05). No results for correlation between VHISS and CBV or MTT survived multiple comparison correction.

CONCLUSIONS

This pilot study is the first to report a significant relationship between the severity of CCSVI and hypoperfusion in the brain parenchyma. These preliminary findings should be confirmed in a larger cohort of MS patients to ensure that they generalize to the MS population as a whole. Reduced perfusion could contribute to the known mechanisms of virtual hypoxia in degenerated axons.

The role of the Met66 brain-derived neurotrophic factor allele in the recovery of executive functioning after combat-related traumatic brain injury

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, promotes survival and synaptic plasticity in the human brain. The Val66Met polymorphism of the BDNF gene interferes with intracellular trafficking, packaging, and regulated secretion of this neurotrophin. The human prefrontal cortex (PFC) shows lifelong neuroplastic adaption implicating the Val66Met BDNF polymorphism in the recovery of higher-order executive functions after traumatic brain injury (TBI). In this study, we examined the effect of this BDNF polymorphism on the recovery of executive functioning after TBI. We genotyped a sample of male Vietnam combat veterans consisting of a frontal lobe lesion group with focal penetrating head injuries and a non-head-injured control group for the Val66Met BDNF polymorphism. The Delis-Kaplan Executive Function System as a standardized psychometric battery was administrated to examine key domains of executive functions. The results revealed that the Met allele but not the hypothesized Val allele promotes recovery of executive functioning. Overall, the Met66 carriers in the lesion group performed as well as the Met66 carriers in the control group. The Met66 allele accounted for 6.2% of variance for executive functioning independently of other significant predictors including preinjury intelligence, left hemisphere volume loss, and dorsolateral PFC volume loss. The findings point to different mechanisms of the Val66Met BDNF gene in complex phenotypes under normal and pathological conditions. A better understanding of these mechanisms could be instrumental in the development and application of effective therapeutic strategies to facilitate recovery from TBI.

BDNF Val66Met polymorphism and brain volumes in multiple sclerosis

Brain derived neurotrophic factor (BDNF) regulates several CNS physiological and pathological processes. To investigate in multiple sclerosis (MS) patients, the relationship between the Val66Met polymorphism of BDNF and clinical markers of disease activity and MRI markers of focal and diffuse brain pathologies. 45 MS patients and 34 healthy controls (HCs) were genotyped and subjected to clinical-MRI examination. Global white matter fraction (gWM-f), gray matter-f (GM-f), cerebrospinal fluid-f (CSF-f), and abnormal WM-f were measured. We studied 26 Val/Val and 19 Val/Met patients and 23 Val/Val and 11 Val/Met HCs. We found that Val/Val patients had lower GM-f and higher CSF-f than Val/Val HCs; such differences were not statistically significant comparing Val/Met patients to HCs. The regression analysis showed that both Val/Met genotype and relapse number were associated with lower CSF-f. Our data suggest that Met allele might be a protective factor against MS as it is associated to a lower brain atrophy.

Correlations between peripheral blood mononuclear cell production of BDNF, TNF-alpha, IL-6, IL-10 and cognitive performances in multiple sclerosis patients

The aim of this study was to investigate the role of Brain Derived Neurotrophic Factor (BDNF) and inflammatory factors in the development of cognitive dysfunctions in Multiple Sclerosis (MS). We correlated peripheral blood mononuclear cell (PBMC) production of BDNF, Tumor Necrosis Factor-alpha (TNF-alpha), Interleukin (IL)-6 and IL-10 with performances on specific neuropsychological tasks in a selected series of MS patients. We studied a sample of 30 patients with relapsing-remitting (RR)MS, segregated by gender and matched for age, education, disease duration, type of immunomodulating therapy, degree of disability and overall cognitive status. We found that low BDNF levels were correlated with increased time of execution on a divided attention and visual scanning task whereas high levels of IL-6 were correlated with low Mini Mental State Examination scores. We did not observe any significant correlations between IL-10, TNF-alpha levels and cognitive performances in our patients. In conclusion our study shows a correlation between low BDNF and high IL-6 production by PBMCs and poorer performances in cognitive tasks in RRMS patients suggesting a possible role of these factors in cognitive impairment in MS.

Effect of Met66 allele of the BDNF rs6265 SNP on regional gray matter volumes in patients with multiple sclerosis: A voxel-based morphometry study

The rs6265 single nucleotide polymorphism (SNP) is a genetic variation in the brain-derived neurotrophic factor (BDNF) gene wherein the presence of the A-allele at rs6265 causes replacement of a valine (Val) at position 66 by methionine (Met). We reported recently that the Met66 allele was associated with lower brain damage as evidenced by measurement of gray matter (GM) volume in multiple sclerosis (MS) patients. The objective of this study was to determine the voxel-wise regional GM differences between the Val66Val and Met66 allele groups in MS patients by using voxel-based morphometry (VBM)-optimized analysis corrected for lesion misclassification in Statistical Parametric Mapping (SPM5). High-resolution 3D-T1-weighted SPGR images from a total of 188 MS patients were acquired on a 1.5T MRI. The Val66Val group included 129 MS patients and the Met66 allele group (comprised of Val66Met or Met66Met genotypes) included 59 MS patients. The SPM analysis of covariance tool was used to assess group differences after controlling for variation in head size, MS disease course and gender. VBM analysis did not yield significant family wise error (FWE) corrected results. This was also confirmed with the non-parametric analysis using threshold-free cluster enhancement (TFCE) method. However, the results from VBM as well as the TFCE analyses (p<0.001, uncorrected) showed higher GM volume in the cingulate of MS patients with Met66 allele than those with Val66Val. Future studies are warranted to investigate longitudinally possible protective role of the Met66 allele of the BDNF rs6265 SNP in relation to specific GM regions.

Magnetic resonance imaging characteristics of children and adults with paediatric-onset multiple sclerosis

The purpose of this study was to compare the clinical and quantitative magnetic resonance imaging metrics of paediatric-onset multiple sclerosis to adult-onset multiple sclerosis. It was a prospective comparison of clinical and magnetic resonance imaging characteristics of two paediatric onset multiple sclerosis and two adult onset multiple sclerosis groups that were matched for disease duration. The paediatric-onset-C group consisted of children with paediatric-onset multiple sclerosis with mean disease duration of 2.7 years, whereas the paediatric onset-A group consisted of adults with mean disease duration of 20 years. The adult onset multiple sclerosis-1 and adult onset multiple sclerosis-2 groups were matched to the paediatric onset-C and paediatric onset-A groups. The brain magnetic resonance imaging measures included: T(1)-, T(2)- and gadolinium contrast-enhancing volumes and the T(2)-lesion volume relative magnetization transfer ratio, global and tissue specific white and grey matter brain atrophy and normal appearing grey and white matter magnetization transfer ratio. Regression analyses were employed for magnetic resonance imaging measures. The paediatric onset multiple sclerosis-C (n = 17) and adult onset multiple sclerosis-1 (n = 81) groups had mean disease duration values of 2.7 +/- standard deviation 2.0 and 2.6 +/- 1.1 years, respectively. The paediatric onset multiple sclerosis-A group (n = 33) and adult onset multiple sclerosis-2 group (n = 300) had mean disease durations of 20 +/- standard deviation 10.9 and 20 +/- 9.3 years, respectively. In regression analysis, the T(2)- lesion volume of the paediatric onset multiple sclerosis-C and adult onset multiple sclerosis-1 groups were similar but there was a trend toward higher T(1)- lesion volume (P = 0.028) in the paediatric onset group. The brain parenchymal fraction and grey matter fraction in the paediatric-onset multiple sclerosis-C group were higher than those for the adult onset multiple sclerosis-1 group (both P < 0.001). The frequency of progressive multiple sclerosis in the paediatric onset multiple sclerosis-A group (27.3%) trended lower (odds ratio = 0.43, P = 0.042) than that in the adult onset multiple sclerosis-2 group (46.3%). The Expanded Disability Status Scale (median; inter-quartile range) in the paediatric onset multiple sclerosis-A group (2.25; 2.5) trended lower (P = 0.058) compared with the adult onset multiple sclerosis-2 group (3.5; 4.0). There was a trend toward lower magnetization transfer ratio values in T(2)-lesions, normal appearing grey matter and normal appearing white matter and higher grey matter fraction in the paediatric onset multiple sclerosis-A group compared with the adult onset multiple sclerosis-2 group. There was no evidence for differences on T(2)-lesion volume, T(1)-lesion volume, brain parenchymal fraction or white matter fraction. Paediatric-onset multiple sclerosis is characterized by a significant disease burden both early and later in the disease course. Despite this, disability is slower to accrue in paediatric onset multiple sclerosis than adult onset multiple sclerosis.

BDNF val66met polymorphism influences motor system function in the human brain

Brain-derived neurotrophic factor (BDNF) is important to brain functions such as plasticity and repair. A single nucleotide polymorphism for this growth factor, val(66)met, is common and associated with decreased activity-dependent BDNF release. The current study evaluated the effects of this polymorphism in relation to human brain motor system function, short-term plasticity, and learning. Functional magnetic resonance imaging (fMRI) scanning during right index finger movement (n = 24) identified activation in a broad sensorimotor network. However, subjects with the polymorphism showed smaller activation volume within several brain regions as compared with subjects without the polymorphism. Repeat fMRI after 25 min of right index finger training found that the 2 genotype groups modulated brain activation differently. In several brain regions, subjects with the polymorphism showed greater activation volume reduction, whereas subjects without the polymorphism showed greater activation volume expansion. On a driving-based motor learning task (independent cohort, n = 29), subjects with the polymorphism showed greater error during short-term learning and poorer retention over 4 days, relative to subjects without the polymorphism. The presence of this BDNF polymorphism is associated with differences in brain motor system function, altered short-term plasticity, and greater error in short-term motor learning. The broader implications of these findings are considered.

MRI characteristics of patients with antiphospholipid syndrome and multiple sclerosis

MRI findings of primary anti-phospholipid antibody syndrome (PAPLS) are difficult to distinguish from those of multiple sclerosis (MS). Only a few previous studies have compared conventional and non-conventional MRI findings in MS and PAPLS patients. In addition, MRI differences between anti-phospholipid antibody (APLA) positive (+) and APLA negative (-) MS patients have not been reported. Therefore, the aim of this study was to investigate the differences in MRI measures among patients with PAPLS, MS and normal control (NC) subjects. We also explored non-conventional MRI measures in APLA+ and APLA- MS patients. Forty-nine (49) consecutive MS patients among whom 39 had relapsing-remitting (RR) and 10 secondary-progressive (SP) disease course, 30 patients with PAPLS and 49 NC were enrolled. Twenty-eight (28) MS patients were APLA+. MRI measures of T1- and T2-lesion volumes (LV) and brain atrophy, including fractions of whole brain (BPF), gray matter (GMF) and white matter (WMF), were evaluated. The magnetization transfer ratio (MTR) of T2- and T1-LVs and different normal-appearing brain tissue (NABT) compartments as well as diffusion-weighted imaging of whole brain mean parenchyma diffusivity (MPD) were obtained. MS patients differed significantly from NC in all MRI measures. PAPLS patients differed from NC in their T2-LV, in MTR measures and in MPD. When MS patients were compared to PAPLS patients, they showed significantly higher T2- and T1-LVs and T2-LV MTR, lower BPF and GMF and higher MPD. APLA+ RR and SPMS (all APLA+) patients showed significantly higher T2-LV, lower GMF, lower normal-appearing gray matter MTR and higher MPD when compared to APLA- patients. The results indicate that brain abnormalities can be detected in PAPLS patients with non-conventional MRI. MRI reveals more profound injury in patients with MS versus PAPLS. APLA mediates heterogeneous cerebral pathology that remains to be further investigated.

Relationship of optic nerve and brain conventional and non-conventional MRI measures and retinal nerve fiber layer thickness, as assessed by OCT and GDx: a pilot study

BACKGROUND

Measurement of retinal nerve fiber layer (RNFL) thickness in multiple sclerosis (MS) is gaining increasing attention.

OBJECTIVES

To explore the relationship between RNFL thickness as measured by optical coherence tomography (OCT) and scanning laser polarimetry with variable corneal compensation (GDx), and conventional and non-conventional optic nerve and brain MRI measures.

METHODS

Twelve relapsing-remitting (RR) MS patients (12 affected and 12 unaffected eyes) and 4 age- and sex-matched normal controls (NC) (8 unaffected eyes) were enrolled. Four MS patients had a history of bilateral optic neuritis (ON), four had a history of unilateral ON, and 4 had no history of ON. Optic nerve MRI measurements included the length of T2 lesions, measurement of optic nerve atrophy, magnetization transfer ratio (MTR) and diffusion tensor imaging (DTI) measures. Optic nerve atrophy was measured by a novel method with high reproducibility. Brain MRI measurements included T1 and T2 lesion volumes (LVs) and their relative MTRs, and tissue class specific atrophy, MTR and DTI measures. Measures of RNFL were evaluated with OCT and GDx. We also evaluated both high and low contrast letter acuities (LCLA) in order to determine the relationship between vision, MRI metrics, and retinal structural architecture.

RESULTS

LCLA, RNFL-OCT and optic nerve radius measures showed more robust differences between NC and MS patients, and between MS patients with affected and unaffected eyes. T2-LV and T1-LV, as well as gray matter atrophy, DTI and MTR measures were related to LCLA and RNFL thickness. Unique additive variance regression models showed that both brain and optic nerve MRI measures independently accounted for about 50% of the variance in LCLA and RNFL thickness. In reverse models, about 20% of the additional independent variance was explained by optic nerve or brain MRI metrics.

CONCLUSIONS

Measurement of RNFL thickness and radius of the optic nerve should be preferred to the other optic nerve MRI measures in clinical studies. Whole brain lesion and GM measures are predictive of impaired visual function with corresponding structural concomitants.

Brain imaging of multiple sclerosis: the next 10 years

MR imaging has had a major impact on understanding the dynamic neuropathologic findings of multiple sclerosis (MS), early diagnosis of the disease, and clinical trial conduct. The next 10 years can be expected to see further advances with a greater emphasis on large multicenter studies, new techniques and hardware allowing greater imaging sensitivity and resolution, and the exploitation of positron emission tomography molecular imaging for MS. The impact should be felt with a new emphasis on gray matter disease and processes of repair. With new ways of monitoring the disease, new treatment targets should become practical, helping to translate advances in the understanding of immunology and regenerative medicine into novel therapies.

Gender-related differences in MS: a study of conventional and nonconventional MRI measures

Background

Studies showed gender-associated differences in multiple sclerosis (MS) disease evolution and in the evolution of conventional magnetic resonance imaging (MRI) findings.

Objective

The aim of this study was to investigate gender differences according to a number of conventional and nonconventional MRI measures in patients with MS.

Methods

We examined 763 consecutive patients with MS [499 (19.2% men) relapsing-remitting (RR), 230 (24.8% men) secondary-progressive, and 34 (44.1% men) primary-progressive], 32 (21.9% men) patients with clinically isolated syndrome (CIS), and 101 (30.7% men) normal controls (NC). Patients were assessed using conventional and nonconventional MRI measures. Gender-related MRI differences were investigated using general linear model analysis, corrected for MS disease type.

Results

In the total MS group, male patients showed lower normalized peripheral gray matter (GM) ( P < 0.001) and normalized GM ( P = 0.011) volumes than female patients. Female patients presented lower normalized white matter (WM) volumes ( P = 0.011). These gender effects were not observed in NC. Male patients also showed more advanced central atrophy ( P = 0.022). In RRMS male patients, there was also a higher lateral ventricle volume ( P = 0.001). The GM-WM normalized ratio was lower for male patients with MS compared with male NC (0.97 vs. 1.09, P < 0.001) but not in patients with CIS compared with NC.

Conclusions

There were no significant gender-related differences regarding nonconventional MRI measures. GM and central atrophy are more advanced in male patients, whereas WM atrophy is more advanced in female patients. These gender-related MRI differences may be explained by the effect of sex hormones on brain damage and repair mechanisms.

A longitudinal observation of brain-derived neurotrophic factor mRNA levels in patients with relapsing-remitting multiple sclerosis

This report is part of a 2-year study assessing the functional effect of Brain-Derived Neurotrophic Factor (BDNF) and its Val66Met polymorphism on a selected population of Relapsing-Remitting Multiple Sclerosis (RRMS) patients from Southern Italy. For this purpose, we measured the peripheral BDNF expression in RRMS patients compared to healthy controls. The influence of concomitant IFNbeta therapy was also evaluated. Thirty-six inactive RRMS patients and 37 healthy controls were genotyped for BDNF Val66Met, and total RNA was extracted at time-points 0-24 months. The BDNF level was quantified by ABI Prism 7900 HT Sequence Detection System, and its relative expression was calculated by the comparative method of 2(-DeltaDeltaCt). At baseline and after 24 months, the BDNF levels of RRMS patients resulted significantly higher than controls (p=0.001), independently of the concomitant IFNbeta treatment; no correlations were found with the investigated clinical and MRI features of MS. Otherwise, carriers of the Met-allele showed significantly higher levels of BDNF in RRMS patients than healthy controls (p=0.005). These data was replicated after a 24-month interval. The present study confirms the increased levels of peripheral BDNF levels in RRMS, even during the inactive phase of the disease. Although with caution due to the small sample size, it also underscores the potential role of the Val66Met polymorphism on the peripheral BDNF expression in RRMS. Functional studies are needed to better clarify this issue.

Myelin repair strategies: a cellular view

PURPOSE OF REVIEW

The development of successful myelin repair strategies depends on the detailed knowledge of the cellular and molecular processes underlying demyelination and remyelination in the central nervous system of animal models and in patients with multiple sclerosis (MS). Based on the complexity of the demyelination and remyelination processes, it should be expected that effective therapeutic approaches will require a combination of strategies for immunomodulation, neuroprotection, and myelin replacement. This brief review highlights recent cellular and molecular findings and indicates that future therapeutic strategies to enhance remyelination may also require combinatorial treatment to accomplish.

RECENT FINDINGS

The relapsing-remitting course of some forms of multiple sclerosis has typically fueled hope for effective repair of multiple sclerosis lesions, if demyelinating activity could be attenuated. Recent findings support the potential of endogenous neural stem cells and progenitor cells to generate remyelinating oligodendrocytes. Importantly, interactions with viable axons and supportive astrocytic responses are required for endogenous immature cells to fulfill their potential remyelinating capacity.

SUMMARY

The research described here will help in identifying the major obstacles to effective remyelination and potential therapeutic targets to guide development of comprehensive approaches for testing in animal models and eventual treatment of patients with multiple sclerosis.

Additive effect of BDNF and REST polymorphisms is associated with improved general cognitive ability

Brain-derived neurotrophic factor (BDNF) is a pleiotropic protein involved in neuronal proliferation, differentiation, synaptic plasticity and survival. Independent studies investigating association between the functional BDNF Val66Met polymorphism and cognitive abilities have reported some conflicting findings, which may reflect inadequate sample size, variation in testing methods, population stratification or the confounding effects of other genes. To test the latter hypothesis, we screened and genotyped polymorphisms in the RE1-silencing transcription factor (REST) gene whose function includes the downregulation of BDNF expression. We identified an exon 4 hexadecapeptide variable number tandem repeat (VNTR) with either four or five copies that was located within a proline-rich domain and investigated a further five single nucleotide polymorphisms (SNPs). Using a cohort of 746 community-dwelling older volunteers, we analysed REST genotype data both independently and in combination with the BDNF Val66Met polymorphism. A haplotype within the REST gene containing the four copy VNTR and a non-synonymous SNP showed a weak but significant association with a higher score of general intelligence (P = 0.05). Analysis of this haplotype and the BDNF Val66Met polymorphism in combination showed a significant interaction (global P-value = 0.0003) with an additive increase in cognitive performance for those possessing the BDNF Val66 allele and the REST haplotype containing the four copy repeat (P = 0.004). The REST haplotypes in combination with the BDNF Met66 polymorphism did not reduce cognitive performance more than the independent influence of the Met66 allele. Our results suggest that investigation of a common REST polymorphism may be necessary to help reduce contrasting reports based around BDNF Val66Met and cognition.

Cognitive dysfunction in MS: bridging the gap between neurocognitive deficits, neuropsychological batteries and MRI

Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the CNS. Its sequelae include both physical and cognitive disability. Advances in neuropsychological testing and screening have led to increased recognition of cognitive impairment in MS; more than half of MS patients have been found to have some degree of cognitive impairment. Strong correlations have been found between neuropsychological testing, brain atrophy and other brain imaging techniques. These tools can aid in the comprehensive evaluation of MS patients. Genetic markers, such as ApoE and brain-derived neurotrophic factor polymorphisms, may also correlate with cognitive impairment in MS. This review details advances in recognizing and predicting cognitive dysfunction in MS. Increased understanding and better evaluation and monitoring of cognitive status in MS may improve the sensitivity of studies designed to test new disease-modifying therapies and interventions for cognitive impairment.

Brain-derived neurotrophic factor polymorphism Val66Met influences cognitive abilities in the elderly

A functional brain-derived neurotrophic factor (BDNF) gene polymorphism (Val66Met) that alters activity-dependent secretion has previously been reported to influence cognitive functioning. A large proportion of these reports suggest that the Met allele, which results in reduced secretion of BDNF, impairs long-term memory as a direct consequence of its influence on hippocampal function but has little influence on working memory. In contrast, other studies have found that the Met allele can also play a protective role in certain neurological conditions and is associated with improved non-verbal reasoning skills in the elderly suggesting effects that appear disease, domain and age specific. We have investigated six haplotype-tagging single nucleotide polymorphisms (SNPs) using a cohort of 722 elderly individuals who have completed cognitive tests that measured the domains of fluid intelligence, processing speed and memory. We found that the presence of the Met allele reduced cognitive performance on all cognitive tests. This reached nominal significance for tests of processing speed (P = 0.001), delayed recall (P = 0.037) and general intelligence (g) (P = 0.008). No association was observed between cognitive tests and any other SNPs once the Val66Met was adjusted for. Our results support initial findings that the Met allele is associated with reduced cognitive functioning. We found no evidence that the Met allele plays a protective role in older non-demented individuals. Magnetic resonance imaging data collected from a subgroup of 61 volunteers showed that the left and right hippocampus were 5.0% and 3.9% smaller, respectively, in those possessing the Met allele, although only a non-significant trend was observed.