Abstract
domenica 27 novembre 2016
A POGLUT1 mutation causes a muscular dystrophy with reduced Notch signaling and satellite cell loss.
First-in-human assessment of PRX002, an anti–α-synuclein monoclonal antibody, in healthy volunteers
ABSTRACT
Background: α-Synuclein is a major component of pathologic inclusions that characterize Parkinson's disease. PRX002 is an antibody that targets α-synuclein, and its murine parent antibody 9E4 has been shown in preclinical studies to reduce α-synuclein pathology and to protect against cognitive and motor deteriorations and progressive neurodegeneration in human α-synuclein transgenic mice. Methods: This first-in-human, randomized, double-blind, placebo-controlled, phase 1 study assessed the impact of PRX002 administered to 40 healthy participants in 5 ascending-dose cohorts (n = 8/cohort) in which participants were randomly assigned to receive a single intravenous infusion of study drug (0.3, 1, 3, 10, or 30 mg/kg; n = 6/cohort) or placebo (n = 2/cohort). Results: PRX002 demonstrated favorable safety, tolerability, and pharmacokinetic profiles at all doses tested, with no immunogenicity. No serious adverse events, discontinuations as a result of adverse events, or dose-limiting toxicities were reported. Serum PRX002 exposure was dose proportional; the average terminal half-life across all doses was 18.2 days. A significant dose-dependent reduction in free serum α-synuclein (unbound to PRX002) was apparent within 1 hour after PRX002 administration, whereas total α-synuclein (free plus bound) increased dose-dependently, presumably because of the expected change in kinetics following antibody binding. Conclusions: This study demonstrates that serum α-synuclein can be safely modulated in a dose-dependent manner after single intravenous infusions of an anti–α-synuclein antibody. These findings support continued development of PRX002, including further characterization of its safety, tolerability, pharmacokinetics, and pharmacodynamic effects in the central nervous system in patients with Parkinson's disease
Movement Disorders 2016
Efficacy of phosphodiesterase-4 inhibitors in juvenile Batten disease (CLN3)
Abstract
Objective
Juvenile neuronal ceroid lipofuscinosis (JNCL), or juvenile Batten disease, is a pediatric lysosomal storage disease caused by autosomal recessive mutations in CLN3, typified by blindness, seizures, progressive cognitive and motor decline, and premature death. Currently, there is no treatment for JNCL that slows disease progression, which highlights the need to explore novel strategies to extend the survival and quality of life of afflicted children. Cyclic adenosine monophosphate (cAMP) is a second messenger with pleiotropic effects, including regulating neuroinflammation and neuronal survival. Here we investigated whether 3 phosphodiesterase-4 (PDE4) inhibitors (rolipram, roflumilast, and PF-06266047) could mitigate behavioral deficits and cell-specific pathology in the Cln3Δex7/8 mouse model of JNCL.
Methods
In a randomized, blinded study, wild-type (WT) and Cln3Δex7/8 mice received PDE4 inhibitors daily beginning at 1 or 3 months of age and continuing for 6 to 9 months, with motor deficits assessed by accelerating rotarod testing. The effect of PDE4 inhibitors on cAMP levels, astrocyte and microglial activation (glial fibrillary acidic protein and CD68, respectively), lysosomal pathology (lysosomal-associated membrane protein 1), and astrocyte glutamate transporter expression (glutamate/aspartate transporter) were also examined in WT and Cln3Δex7/8 animals.
Results
cAMP levels were significantly reduced in the Cln3Δex7/8 brain, and were restored by PF-06266047. PDE4 inhibitors significantly improved motor function in Cln3Δex7/8 mice, attenuated glial activation and lysosomal pathology, and restored glutamate transporter expression to levels observed in WT animals, with no evidence of toxicity as revealed by blood chemistry analysis.
Interpretation
These studies reveal neuroprotective effects for PDE4 inhibitors in Cln3Δex7/8 mice and support their therapeutic potential in JNCL patients.
Ann Neurol 2016
Early lipofuscin accumulation in frontal lobe epilepsy
Abstract
Objective
This study reports on a novel brain pathology in young patients with frontal lobe epilepsy (FLE) that is distinct from focal cortical dysplasia (FCD).
Methods
Surgical specimens from 20 young adults with FLE (mean age, 30 years) were investigated with histological/immunohistochemical markers for cortical laminar architecture, mammalian target of (mTOR) pathway activation and inhibition, cellular autophagy, and synaptic vesicle-mediated trafficking as well as proteomics analysis. Findings were correlated with pre-/postoperative clinical, imaging, and electrophysiological data.
Results
Excessive lipofuscin accumulation was observed in abnormal dysmorphic neurones in 6 cases, but not in seven FCD type IIB and 7 pathology-negative cases, despite similar age and seizure histories. Abnormal dysmorphic neurones on proteomics analysis were comparable to aged human brains. The mTOR pathway was activated, as in cases with dysplasia, but the immunoreactivities of nucleoporin p62, DEP-domain containing protein 5, clathrin, and dynamin-1 were different between groups, suggesting that enhanced autophagy flux and abnormal synaptic vesicle trafficking contribute to early lipofuscin aggregation in these cases, compared to suppression of autophagy in cases with typical dysplasia. Cases with abnormal neuronal lipofuscin showed subtle magnetic resonance imaging cortical abnormalities that localized with seizure onset zone and were more likely to have a family history.
Interpretation
We propose that excess neuronal lipofuscin accumulation in young patients with FLE represents a novel pathology underlying this epilepsy; the early accumulation of lipofuscin may be disease driven, secondary to as-yet unidentified drivers accelerating autophagic pathways, which may underpin the neuronal dysfunction in this condition.
Ann Neurol 2016
Cryptococcal meningitis: epidemiology, immunology, diagnosis and therapy
HIV-associated cryptococcal meningitis is by far the most common cause of adult meningitis in many areas of the world that have high HIV seroprevalence. In most areas in Sub-Saharan Africa, the incidence of cryptococcal meningitis is not decreasing despite availability of antiretroviral therapy, because of issues of adherence and retention in HIV care. In addition, cryptococcal meningitis in HIV-seronegative individuals is a substantial problem: the risk of cryptococcal infection is increased in transplant recipients and other individuals with defects in cell-mediated immunity, and cryptococcosis is also reported in the apparently immunocompetent. Despite therapy, mortality rates in these groups are high. Over the past 5 years, advances have been made in rapid point-of-care diagnosis and early detection of cryptococcal antigen in the blood. These advances have enabled development of screening and pre-emptive treatment strategies aimed at preventing the development of clinical infection in patients with late-stage HIV infection. Progress in optimizing antifungal combinations has been aided by evaluation of the clearance rate of infection by using serial quantitative cultures of cerebrospinal fluid (CSF). Measurement and management of raised CSF pressure, a common complication, is a vital component of care. In addition, we now better understand protective immune responses in HIV-associated cases, immunogenetic predisposition to infection, and the role of immune-mediated pathology in patients with non-HIV associated infection and in the context of HIV-associated immune reconstitution reactions.
Nature Reviews Neurology 2016
Evaluation of Cognitive Deficits and Structural Hippocampal Damage in Encephalitis With Leucine-Rich, Glioma-Inactivated 1 Antibodies
Abstract
Importance Limbic encephalitis with leucine-rich, glioma-inactivated 1 (LGI1) antibodies is one of the most frequent variants of autoimmune encephalitis with antibodies targeting neuronal surface antigens. However, the neuroimaging pattern and long-term cognitive outcome are not well understood.
Objective To study cognitive outcome and structural magnetic resonance imaging (MRI) alterations in patients with anti-LGI1 encephalitis.
Design, Setting, and Participants A cross-sectional study was conducted at the Departments of Neurology at Charité-Universitätsmedizin Berlin and University Hospital Schleswig-Holstein, Kiel, Germany. Data on 30 patients with anti-LGI1 encephalitis and 27 healthy control individuals matched for age, sex, and educational level were collected from June 1, 2013, through February 28, 2015.
Main Outcomes and Measures Clinical assessment, cognitive testing, and high-resolution MRI data, including whole-brain, hippocampal and basal ganglia volumetry; white matter integrity (diffusion tensor imaging); gray matter density (voxel-based morphometry); and hippocampal microstructural integrity (mean diffusivity and fractional anisotropy).
Results Of the 30 patients included in the study, 19 were male (63%); mean (SD) age was 65.7 (12.3) years. Patients with anti-LGI1 encephalitis had incomplete recovery with significant and persisting verbal (mean [SE] Rey Auditory Verbal Learning Test [RAVLT], delayed recall: patients, 6.52 [1.05]; controls, 11.78 [0.56], P < .001) and visuospatial (Rey-Osterrieth Complex Figure Test [ROCF], delayed recall: patients, 16.0 [1.96]; controls, 25.86 [1.24]; P < .001) memory deficits. These deficits were accompanied by pronounced hippocampal atrophy, including subfields cornu ammonis 2/3 (CA2/3) and CA4/dentate gyrus (DG), as well as impaired hippocampal microstructural integrity. Higher disease severity correlated with larger verbal memory deficits (RAVLT delayed recall, r = −0.40; P = .049), decreased volumes of left hippocampus (r = −0.47; P = .02) and left CA2/3 (r = −0.41; P = .04) and CA4/DG (r = −0.43; P = .03) subfields, and impaired left hippocampal microstructural integrity (r = 0.47; P = .01). In turn, decreased volume of the left CA2/3 subfield (RAVLT delayed recall, r = 0.40; P = .047) and impaired left hippocampal microstructural integrity (RAVLT recognition, r = −0.41; P = .04) correlated with verbal memory deficits. Basal ganglia MRI signal abnormalities were observed in only 1 patient, but a longer duration of faciobrachial dystonic seizures correlated with a reduction of pallidum volume (r = −0.71; P = .03). In contrast, no abnormalities of cortical gray matter or white matter were found. The latency between disease onset and initiation of immunotherapy was significantly correlated with verbal (RAVLT recall after interference, r = −0.48; P = .02) and visuospatial (ROCF delayed recall, r = −0.46; P = .03) memory deficits.
Conclusions and Relevance Anti-LGI1 encephalitis is associated with cognitive deficits and disability as a result of structural damage to the hippocampal memory system. This damage might be prevented by early immunotherapy.
JAMA Neurology 2016
Durability of the Rituximab Response in Acetylcholine Receptor Autoantibody–Positive Myasthenia Gravis
Abstract
Importance Myasthenia gravis (MG), an autoimmune disorder of neuromuscular transmission, is treated by an array of immunotherapeutics, many of which are nonspecific. Even with current therapies, a subset of patients has medically refractory MG. The benefits of B-cell–targeted therapy with rituximab have been observed in MG; however, the duration of these benefits after treatment is unclear.
Objective To evaluate the durability of response to rituximab in the treatment of acetylcholine receptor autoantibody–positive (AChR+) generalized MG.
Design, Setting and Participants This retrospective case series study included 16 patients with AChR+ MG referred to an MG clinic from January 1, 2007, to December 31, 2015. The patients were treated with rituximab and followed up for 18 to 84 months after treatment.
Main Outcomes and Measures Assessment of long-term clinical response, durability of response and/or relapse rate, AChR autoantibody levels, adverse effects, and inflammatory markers.
Results In the 16 patients (6 men and 10 women; median age, 42 [range, 18-69] years), clinical improvement was observed in parallel with complete withdrawal or reduction of other immunotherapies, with all patients achieving complete stable remission, pharmacologic remission, or minimal manifestations based on the Myasthenia Gravis Foundation of America postintervention status criteria. Nine patients (56%) had a relapse during a mean follow-up of 36 (range, 24-47) months. Seven patients (44%) remained relapse free with a mean follow-up of 47 (range, 18-81) months since the last rituximab treatment. All values were normalized to a pretreatment anti-AChR antibody level of 100% and the mean levels after each rituximab cycle were calculated. A 33% decrease was seen after cycle 1 of rituximab treatment (100% vs 67%; P = .004); 20% after cycle 2 (compared with cycle 1) (67% vs 47%; P = .008); and 17% after cycle 3 (compared with cycle 2) (47% vs 30%; P = .02). However, the serum cytokine levels measured were found to be unchanged.
Conclusions and Relevance Rituximab therapy appears to be an effective option in patients with refractory AChR+ MG, who were observed to have a durable response after treatment. Identification of markers of disease relapse and sustained remission are critical next steps in the development of pathophysiology-relevant, evidence-based practice parameters for rituximab in the treatment of MG.
JAMA Neurology 2016
Efficacy, safety, and tolerability of lacosamide monotherapy versus controlled-release carbamazepine in patients with newly diagnosed epilepsy: a phase 3, randomised, double-blind, non-inferiority trial
Summary
Further options for monotherapy are needed to treat newly diagnosed epilepsy in adults. We assessed the efficacy, safety, and tolerability of lacosamide as a first-line monotherapy option for these patients.
Methods
In this phase 3, randomised, double-blind, non-inferiority trial, patients from 185 epilepsy or general neurology centres in Europe, North America, and the Asia Pacific region, aged 16 years or older and with newly diagnosed epilepsy were randomly assigned in a 1:1 ratio, via a computer-generated code, to receive lacosamide monotherapy or controlled-release carbamazepine (carbamazepine-CR) twice daily. Patients, investigators, and trial personnel were masked to treatment allocation. From starting doses of 100 mg/day lacosamide or 200 mg/day carbamazepine-CR, uptitration to the first target level of 200 mg/day and 400 mg/day, respectively, took place over 2 weeks. After a 1-week stabilisation period, patients entered a 6-month assessment period. If a seizure occurred, the dose was titrated to the next target level (400 or 600 mg/day for lacosamide and 800 or 1200 mg/day for carbamazepine-CR) over 2 weeks with a 1-week stabilisation period, and the 6-month assessment period began again. Patients who completed 6 months of treatment and remained seizure-free entered a 6-month maintenance period on the same dose. The primary efficacy outcome was the proportion of patients remaining free from seizures for 6 consecutive months after stabilisation at the last assessed dose. The predefined non-inferiority criteria were −12% absolute and −20% relative difference between treatment groups. This trial is registered with ClinicalTrials.gov, number NCT01243177.
Findings
The trial was done between April 27, 2011, and Aug 7, 2015. 888 patients were randomly assigned treatment. 444 patients taking lacosamide and 442 taking carbamazepine-CR were included in the full analysis set (took at least one dose of study treatment), and 408 and 397, respectively, were included in the per-protocol set. In the full analysis set, 327 (74%) patients in the lacosamide group and 308 (70%) in the carbamazepine-CR group completed 6 months of treatment without seizures. The proportion of patients in the full analysis set predicted by the Kaplan-Meier method to be seizure-free at 6 months was 90% taking lacosamide and 91% taking carbamazepine-CR (absolute treatment-difference: −1·3%, 95% CI −5·5 to 2·8 relative treatment difference: −6·0%). Kaplan-Meier estimates results were similar in the per-protocol set (92% and 93%; −1·3%, −5·3 to 2·7; −5·7%). Treatment-emergent adverse events were reported in 328 (74%) patients receiving lacosamide and 332 (75%) receiving carbamazepine-CR. 32 (7%) patients taking lacosamide and 43 (10%) taking carbamazepine-CR had serious treatment-emergent adverse events, and 47 (11%) and 69 (16%), respectively, had treatment-emergent adverse events that led to withdrawal.
Interpretation
Treatment with lacosamide met the predefined non-inferiority criteria when compared with carbamazepine-CR. Therefore, it might be useful as first-line monotherapy for adults with newly diagnosed epilepsy.
Lancet Neurology
Evolving use of seizure medications after intracerebral hemorrhage A multicenter study
ABSTRACT
Objective: Prophylactic medications can be a source of preventable harm, potentially affecting large numbers of patients. Few data exist about how clinicians change prescribing practices in response to new data and revisions to guidelines about preventable harm from a prophylactic medication. We sought to determine the changes in prescribing practice of seizure medications for patients with intracerebral hemorrhage (ICH) across a metropolitan area before and after new outcomes data and revised prescribing guidelines were published.
Methods: We conducted an observational study using electronic medical record data from 4 academic medical centers in a large US metropolitan area.
Results: A total of 3,422 patients with ICH, diagnosed between 2007 and 2012, were included. In 2009, after a publication found an association of phenytoin with higher odds of dependence or death, the use of phenytoin declined from 9.6% in 2009 to 2.2% in 2012 (p < 0.00001). Conversely, the use of levetiracetam more than doubled, from 15.1% in 2007 to 35% in 2012 (p < 0.00001). Use of levetiracetam varied among the 4 institutions from 6.7% to 29.8% (p < 0.00001).
Conclusions: New data that led to revised prescribing guidelines for prophylactic seizure medications for patients with ICH were temporally associated with a significant decrease in use of the medication, potentially reducing adverse outcomes. However, a corresponding increase in the use of an alternative medication, levetiracetam, occurred despite limited knowledge about its potential effects on outcomes. Future guideline changes should anticipate and address alternatives.
Neurology 2016
Sleep-related hypermotor epilepsy Long-term outcome in a large cohort
ABSTRACT
Objective: To assess the long-term outcome of sleep-related hypermotor epilepsy (SHE).
Methods: We retrospectively reconstructed a representative cohort of patients diagnosed with SHE according to international diagnostic criteria, sleep-related seizures ≥75% and follow-up ≥5 years. Terminal remission (TR) was defined as a period of ≥5 consecutive years of seizure freedom at the last follow-up. We used Kaplan-Meier estimates to calculate the cumulative time-dependent probability of TR and to generate survival curves. Univariate and multivariate Cox regression analyses were performed.
Results: We included 139 patients with a 16-year median follow-up (2,414 person-years). The mean age at onset was 13 ± 10 years. SHE was sporadic in 86% of cases and familial in 14%; 16% of patients had underlying brain abnormalities. Forty-five percent of patients had at least 1 seizure in wakefulness lifetime and 55% had seizures only in sleep (typical SHE). At the last assessment, 31 patients achieved TR (TR group, 22.3%), while 108 (NTR group, 77.7%) still had seizures or had been in remission for <5 years. The cumulative TR rate was 20.4%, 23.5%, and 28.4% by 10, 20, and 30 years from inclusion. At univariate analysis, any underlying brain disorder (any combination of intellectual disability, perinatal insult, pathologic neurologic examination, and brain structural abnormalities) and seizures in wakefulness were more frequent among the NTR group (p = 0.028; p = 0.043). Absence of any underlying brain disorder (hazard ratio 4.21, 95% confidence interval 1.26–14.05, p = 0.020) and typical SHE (hazard ratio 2.76, 95% confidence interval 1.31–5.85, p = 0.008) were associated with TR.
Conclusions: Our data show a poor prognosis of SHE after a long-term follow-up. Its outcome is primarily a function of the underlying etiology.
Neurology 2016
sabato 19 novembre 2016
Cutaneous malignant melanoma and Parkinson disease: Common pathways?
Abstract
The mechanisms underlying the high prevalence of cutaneous malignant melanoma (CMM) in Parkinson disease (PD) are unclear, but plausibly involve common pathways. 129Ser-phosphorylated α-synuclein, a pathological PD hallmark, is abundantly expressed in CMM, but not in normal skin. In inherited PD, PARK genes harbor germline mutations; the same genes are somatically mutated in CMM, or their encoded proteins are involved in melanomagenesis. Conversely, genes associated with CMM affect PD risk. PD/CMM-targeted cells share neural crest origin and melanogenesis capability. Pigmentation gene variants may underlie their susceptibility. We review putative genetic intersections that may be suggestive of shared pathways in
neurodegeneration/melanomagenesis.
Ann Neurol 2016
Neuroinflammation — using big data to inform clinical practice
Abstract
Neuroinflammation is emerging as a central process in many neurological conditions, either as a causative factor or as a secondary response to nervous system insult. Understanding the causes and consequences of neuroinflammation could, therefore, provide insight that is needed to improve therapeutic interventions across many diseases. However, the complexity of the pathways involved necessitates the use of high-throughput approaches to extensively interrogate the process, and appropriate strategies to translate the data generated into clinical benefit. Use of 'big data' aims to generate, integrate and analyse large, heterogeneous datasets to provide in-depth insights into complex processes, and has the potential to unravel the complexities of neuroinflammation. Limitations in data analysis approaches currently prevent the full potential of big data being reached, but some aspects of big data are already yielding results. The implementation of 'omics' analyses in particular is becoming routine practice in biomedical research, and neuroimaging is producing large sets of complex data. In this Review, we evaluate the impact of the drive to collect and analyse big data on our understanding of neuroinflammation in disease. We describe the breadth of big data that are leading to an evolution in our understanding of this field, exemplify how these data are beginning to be of use in a clinical setting, and consider possible future directions.
Nature Reviews Neurology 2016
Association of Brain Amyloid-β With Slow Gait in Elderly Individuals Without Dementia Influence of Cognition and Apolipoprotein E ε4 Genotype
Abstract
Importance Motor slowing appears in preclinical Alzheimer disease (AD), progresses with AD progression, and is associated with AD pathologic findings at autopsy. Whether amyloid-β (Aβ) is associated with gait speed in elderly individuals without dementia and whether cognition and apolipoprotein E ε4 (APOE ε4) influence this association remain unknown.
Objectives To examine the association between Aβ and gait speed in elderly individuals without dementia and to study the influence of cognition and APOE ε4 status on this association.
Design, Setting, and Participants This cross-sectional analysis included 183 elderly individuals without dementia, including a cognitively normal (CN) subsample of 144 adults, enrolled in the Ginkgo Evaluation of Memory study at a university center from January 1, 2000, through December 31, 2009, and enrolled in a follow-up substudy a mean (SD) of 10 (3) months after the initial study closeout. Data analysis was performed from October 1, 2015, to June 1, 2016.
Main Outcomes and Measures We assessed cerebral Aβ on Pittsburgh Compound B (PiB) positron emission tomography, gait speed over 4.57 m (15 ft), and cognition on the Mini-Mental State Examination and Trail Making Test Parts A and B. We grouped participants into high Aβ (PiB+) and low Aβ (PiB–) groups on standardized global PiB cutoffs and examined group differences. We studied the influence of cognition and APOE ε4 on the global and regional associations between gait speed and Aβ in the whole sample and the CN subsample.
Results Among the 183 study participants, mean (SD) age was 85.5 (3) years, 76 were women (41.5%), and 177 were white (96.7%). The PiB+ individuals were comparable to the PiB– individuals on demographics, comorbidities, cognition, hippocampal volume, and small-vessel disease but not on gait speed (0.85 vs 0.92 m/s, P = .01) or proportion of APOE ε4 carriers (29 [29.0%] vs 5 [6.0%], P < .001). In the whole sample and the CN subsample, the association between global PiB retention and slower gait withstood adjustment for covariates (β = −0.068, P = .03 and β = −0.074, P = .04, respectively); however, this association was attenuated by Mini-Mental State Examination and Trail Making Test Parts A and B and was rendered statistically nonsignificant by APOE ε4 in both samples (β = −0.055 and β = −0.058, respectively; both P ≥ .10). Several regional associations between gait speed and PiB uptake withstood relevant adjustments; however, APOE ε4 rendered only the medial (β = −0.22, P = .03) and lateral (β = −0.08, P = .03) temporal regions, subcortical white matter (β = −0.13, P = .02), and occipital regions (β = −0.15, P = .03) in the whole sample and the occipital regions (β = −0.21, P = .01) in the CN subsample statistically significant.
Conclusions and Relevance Cerebral Aβ deposition is associated with slower gait speed in elderly individuals without dementia; however, this association is weaker in those who are CN. Cognition and APOE ε4 carrier status influence the association between Aβ and gait speed in elderly individuals without dementia.
JAMA Neurology 2016
Association of Amyloid Pathology With Myelin Alteration in Preclinical Alzheimer Disease
Abstract
Importance The accumulation of aggregated β-amyloid and tau proteins into plaques and tangles is a central feature of Alzheimer disease (AD). While plaque and tangle accumulation likely contributes to neuron and synapse loss, disease-related changes to oligodendrocytes and myelin are also suspected of playing a role in development of AD dementia. Still, to our knowledge, little is known about AD-related myelin changes, and even when present, they are often regarded as secondary to concomitant arteriosclerosis or related to aging.
Objective To assess associations between hallmark AD pathology and novel quantitative neuroimaging markers while being sensitive to white matter myelin content.
Design, Setting, and Participants Magnetic resonance imaging was performed at an academic research neuroimaging center on a cohort of 71 cognitively asymptomatic adults enriched for AD risk. Lumbar punctures were performed and assayed for cerebrospinal fluid (CSF) biomarkers of AD pathology, including β-amyloid 42, total tau protein, phosphorylated tau 181, and soluble amyloid precursor protein. We measured whole-brain longitudinal and transverse relaxation rates as well as the myelin water fraction from each of these individuals.
Main Outcomes and Measures Automated brain mapping algorithms and statistical models were used to evaluate the relationships between age, CSF biomarkers of AD pathology, and quantitative magnetic resonance imaging relaxometry measures, including the longitudinal and transverse relaxation rates and the myelin water fraction.
Results The mean (SD) age for the 19 male participants and 52 female participants in the study was 61.6 (6.4) years. Widespread age-related changes to myelin were observed across the brain, particularly in late myelinating brain regions such as frontal white matter and the genu of the corpus callosum. Quantitative relaxometry measures were negatively associated with levels of CSF biomarkers across brain white matter and in areas preferentially affected in AD. Furthermore, significant age-by-biomarker interactions were observed between myelin water fraction and phosphorylated tau 181/β-amyloid 42, suggesting that phosphorylated tau 181/β-amyloid 42 levels modulate age-related changes in myelin water fraction.
Conclusions and Relevance These findings suggest amyloid pathologies significantly influence white matter and that these abnormalities may signify an early feature of the disease process. We expect that clarifying the nature of myelin damage in preclinical AD may be informative on the disease’s course and lead to new markers of efficacy for prevention and treatment trials.
JAMA Neurology 2016
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