Cognitive Preservation Research Articles

Glioma surgery in eloquent areas: can we preserve cognition?

BackgroundCognitive preservation is crucial in glioma surgery, as it is an important aspect of daily life functioning. Several studies claimed that surgery in eloquent areas is possible without causing severe cognitive damage. However, this conclusion was relatively ungrounded due to the lack of extensive neuropsychological testing in homogenous patient groups. In this study, we aimed to elucidate the short-term and long-term effects of glioma surgery on cognition by identifying all studies who conducted neuropsychological tests preoperatively and postoperatively in glioma patients.MethodsWe systematically searched the electronical databases Embase, Medline OvidSP, Web of Science, PsychINFO OvidSP, PubMed, Cochrane, Google Scholar, Scirius and Proquest aimed at cognitive performance in glioma patients preoperatively and postoperatively.ResultsWe included 17 studies with tests assessing the cognitive domains: language, memory, attention, executive functions and/or visuospatial abilities. Language was the domain most frequently examined. Immediately postoperatively, all studies except one, found deterioration in one or more cognitive domains. In the longer term (3–6/6–12 months postoperatively), the following tests showed both recovery and deterioration compared with the preoperative level: naming and verbal fluency (language), verbal word learning (memory) and Trailmaking B (executive functions).ConclusionsCognitive recovery to the preoperative level after surgery is possible to a certain extent; however, the results are too arbitrary to draw definite conclusions and not all studies investigated all cognitive domains. More studies with longer postoperative follow-up with tests for cognitive change are necessary for a better understanding of the conclusive effects of glioma surgery on cognition.

Regional cortical thinning in multiple sclerosis and its relation with cognitive impairment: A multicenter study

Objectives: The objectives of this paper are to compare in a multicenter setting patterns of regional cortical thickness in patients with relapsing–remitting multiple sclerosis (RRMS) and cognitive impairment (CI) and those cognitively preserved (CP), and explore the relationship between cortical thinning and cognitive performance. Methods: T1-weighted isotropic brain scans were collected at 3T from seven European centers in 60 RRMS patients and 65 healthy controls (HCs). Patients underwent clinical and neuropsychological examinations. Cortical thickness (CTh) measures were calculated using FreeSurfer (failing in four) and both lobar and vertex-based general linear model (GLM) analyses were compared between study groups. Results: Twenty (36%) MS patients were classified as CI. Mean global CTh was smaller in RRMS patients compared to HCs (left 2.43 vs. 2.53 mm, right 2.44 vs. 2.54 mm, p < 0.001). Multivariate GLM regional analysis showed significantly more temporal thinning in CI compared to CP patients. Verbal memory scores correlated to regional cortical thinning in the insula whereas visual memory scores correlated to parietal thinning. Conclusions: This multicenter study showed mild global cortical thinning in RRMS. The extent of thinning is less pronounced than previously reported. Only subtle regional differences between CI and CP patients were observed, some of which related to specific cognitive domains.

Structural MRI substrates of cognitive impairment in neuromyelitis optica.

To identify the clinical and structural MRI markers for predicting cognitive impairment (CI) in patients with neuromyelitis optica (NMO). Fifty-four patients with NMO and 27 healthy controls underwent extensive neuropsychological testing and multimodal 3.0T MRI. The patient group was classified as CI or cognitively preserved (CP), using a criterion of ≤1.5 SD on at least 2 cognitive domains. MRI measurements included white matter (WM) lesion volume, gray matter (GM), WM, and deep GM (DGM) volume, cortical thickness, and the severity and extent of WM tract diffusion metric alterations based on fractional anisotropy and mean, axial, and radial diffusivity. Groups were compared using a multivariate general linear model, and clinical and MRI measurements were related to average cognition z scores by partial correlations and a stepwise linear regression model. Twenty-six patients with NMO (48.2%) were classified as CI and showed WM tract diffusion abnormalities, particularly increased radial diffusivity, and GM especially DGM atrophy compared with healthy controls. Patients classified as CP also showed alterations of WM tract diffusion but without significant GM atrophy. Compared with the CP group, patients with CI demonstrated a lower level of education and decreased hippocampal volume. In the whole patient group, average cognition z scores were best predicted by the level of education and hippocampal volume (R(2) = 0.46, p < 0.001). In patients with NMO, WM tract integrity disruption was identified in both CP and CI groups. GM atrophy, particularly in the DGM, was only found in the CI group. Hippocampal volume is the main MRI predictor of cognition in NMO.

Cognitive impairment and memory disorders in relapsing-remitting multiple sclerosis: the role of white matter, gray matter and hippocampus.

Cognitive disorders occur in up to 65 % of multiple sclerosis (MS) patients; they have been correlated with different MRI measures of brain tissue damage, whole and regional brain atrophy. The hippocampal involvement has been poorly investigated in cognitively impaired (CI) MS patients. The objective of this study is to analyze and compare brain tissue abnormalities, including hippocampal atrophy, in relapsing-remitting MS (RRMS) patients with and without cognitive deficits, and to investigate their role in determining cognitive impairment in MS. Forty-six RRMS patients [20 CI and 26 cognitively preserved (CP)] and 25 age, sex and education-matched healthy controls (HCs) underwent neuropsychological evaluation and 3-Tesla anatomical MRI. T2 lesion load (T2-LL) was computed with a semiautomatic method, gray matter volume and white matter volume were estimated using SIENAX. Hippocampal volume (HV) was obtained by manual segmentation. Brain tissues volumes were compared among groups and correlated with cognitive performances. Compared to HCs, RRMS patients had significant atrophy of WM, GM, left and right Hippocampus (p < 0.001). Compared to CP, CI RRMS patients showed higher T2-LL (p = 0.02) and WM atrophy (p = 0.01). In the whole RRMS group, several cognitive tests correlated with brain tissue abnormalities (T2-LL, WM and GM atrophy); only verbal memory performances correlated with left hippocampal atrophy. Our results emphasize the role of T2-LL and WM atrophy in determining clinically evident cognitive impairment in MS patients and provide evidence that GM and hippocampal atrophy occur in MS patients regardless of cognitive status.

The implications of age-related neurofunctional compensatory mechanisms in executive function and language processing including the new Temporal Hypothesis for Compensation.

As the passage of time structurally alters one’s brain, cognition does not have to suffer the same faith, at least not to the same extent. Indeed, the existence of age-related compensatory mechanisms allow for some cognitive preservation. This paper attempts to coherently review the existing concepts of neurofunctional compensation when applied to two different cognitive domains, namely executive function and language processing. More precisely, we explore the Cognitive reserve (CR) model in healthy aging as well as its two underlying mechanisms: neural reserve and neural compensation. Furthermore, we review the Compensation-Related Utilization of Neural Circuits Hypothesis as well as the Growing Of Life Differences Explains Normal Aging model. Finally, we propose, based on some functional neuroimaging studies, the existence of another compensatory mechanism characterized by age-related delayed cerebral activation allowing for cognitive performance to be preserved at the expense of speed processing: the Temporal Hypothesis for Compensation.

Cognitive Reserve and Preservation of Functioning Following Traumatic Brain Injury (P7.188)

Cognitive Reserve and Preservation of Functioning Following Traumatic Brain Injury (P7.188)

Human neural stem cell transplantation provides long-term restoration of neuronal plasticity in the irradiated hippocampus.

For the majority of CNS malignancies, radiotherapy provides the best option for forestalling tumor growth, but is frequently associated with debilitating and progressive cognitive dysfunction. Despite the recognition of this serious side effect, satisfactory long-term solutions are not currently available and have prompted our efforts to explore the potential therapeutic efficacy of cranial stem cell transplants. We have demonstrated that intrahippocampal transplantation of human neural stem cells (hNSCs) can provide long-lasting cognitive benefits using an athymic rat model subjected to cranial irradiation. To explore the possible mechanisms underlying the capability of engrafted cells to ameliorate radiation-induced cognitive dysfunction we analyzed the expression patterns of the behaviorally induced activity-regulated cytoskeleton-associated protein (Arc) in the hippocampus at 1 and 8 months postgrafting. While immunohistochemical analyses revealed a small fraction (4.5%) of surviving hNSCs in the irradiated brain that did not express neuronal or astroglial makers, hNSC transplantation impacted the irradiated microenvironment of the host brain by promoting the expression of Arc at both time points. Arc is known to play key roles in the neuronal mechanisms underlying long-term synaptic plasticity and memory and provides a reliable marker for detecting neurons that are actively engaged in spatial and contextual information processing associated with memory consolidation. Cranial irradiation significantly reduced the number of pyramidal (CA1) and granule neurons (DG) expressing behaviorally induced Arc at 1 and 8 months postirradiation. Transplantation of hNSCs restored the expression of plasticity-related Arc in the host brain to control levels. These findings suggest that hNSC transplantation promotes the long-term recovery of host hippocampal neurons and indicates that one mechanism promoting the preservation of cognition after irradiation involves trophic support from engrafted cells.

Cognitive impairment in Chinese neuromyelitis optica

Background: Cognitive dysfunction is frequently seen in neuromyelitis optica (NMO). However, the features and influencing factors of cognitive impairment of Chinese NMO patients are unclear. Objective: To investigate the patterns of cognitive impairment in Chinese NMO patients, and correlate the neuropsychiatric scores with clinical and MRI parameters. Methods: Thirty-six Chinese NMO patients, and 30 sex and age-matched healthy controls were recruited with extensive neuropsychological assessments, using the modified Minimal Assessment of Cognitive Function in MS (MACFIMS). The demographic and clinical characteristics as well as MRI parameters were compared between cognitively impaired (CI) and cognitively preserved (CP) patients. Results: NMO patients were significantly impaired in the Paced Auditory Serial Addition Task (P<0.05), the Symbol Digit Modalities Test (P<0.001), the California Verbal Learning Test-Second Edition (P<0.05), the Brief Visuospatial Memory Test-Revised (P<0.05) and semantic fluency (P<0.001). Only lower education level was associated with cognitive dysfunction in NMO (odds ratio: 0.57, P<0.05). There were no significant differences of MRI parameters regarding white matter (WM) lesions, grey matter and WM brain volume between CI and CP patients. Conclusions: Chinese NMO patients particularly demonstrated cognitive impairment in information processing speed, executive function and memory. Lower education level was the main factor contributing to cognitive impairment in NMO.

Plasma Fatty Acid Profiles in Relation to Cognition and Gender in Alzheimer's Disease Patients During Oral Omega-3 Fatty Acid Supplementation: The OmegAD Study.

ω3 fatty acids (ω3 FAs) may slow the rate of decline in cognitive performance in mild forms of cognitive impairment and Alzheimer's disease (AD). However, the relationship between changes of plasma ω3 FA levels and cognitive performance, as well as effects of gender, are poorly known. To study the effect of 6-month administration of DHA-rich ω3 FA supplementation on plasma FA profiles in patients with mild to moderate AD in relation to cognitive performance and gender. This investigation is part of the OmegAD Study. 174 AD patients (74 ± 9 years) were randomized to a daily intake of 2.3 g ω3 FA or placebo for 6 months; subsequently all received the ω3 FA preparation for the next 6 months. Baseline as well as changes in plasma levels of the main ω3 FAs in 165 patients, while receiving ω3 FA supplementation for 6 months, were analyzed for association to cognitive performance (assessed by ADAS-cog and MMSE scores) as well as to gender. Preservation of cognitive functioning, assessed by ADAS-cog or its sub-items (but not MMSE) scores, was significantly associated to increasing plasma ω3 FA levels over time. Thus, the higher ω3 FA plasma levels rose, the lower was the rate of cognitive deterioration. This effect was not related to gender; since although females displayed higher ω3 FA plasma levels than did males after 6 months of supplementation, this difference disappeared when adjusted for body weight. Since our study suggests dose-response relationships between plasma levels of ω3 FA and preservation of cognition, future ω3 FA trials in patients with mild AD should consider exploring graded (and body weight adjusted) doses of ω3 FA.

Cognitive Deficits and Behavioral Disorders in Children: A Comprehensive Multidisciplinary Approach to Management

Preservation of human cognition is an important objective of the health policies of both developed and developing countries in this era of rapid demographic transition. Threat to human cognition can occur at any age in either sex due to diverse causes. Cognitive impairments pose a major obstacle to the social and economic development of any nation. Therefore, it is essential to implement a policy of “Cognitive Watch” to prevent cognitive deficits and decline in children. Management of cognitive deficits in children is quite challenging since the plasticity of a growing brain is different from that of an adult brain in several aspects. The conditions leading to cognitive deficits in children are heterogeneous with respect to etiology, pathology and pathogenesis. This review addresses some of the important conditions leading to cognitive deficits in children and their optimal management. It focuses on diverse theories of cognitive development, diverse conditions leading to cognitive decline, the biological, genetic, metabolic and endocrine mechanisms leading to pathogenesis, and suitable intervention strategies, so that it is possible to approach cognitive deficits from their developmental perspective, leading to a comprehensive multidisciplinary management. There are several classifications for cognitive deficits and intellectual disability in children but most of them are distributed and fragmented, since there is no uniform pattern of classification. Etiology- and pathology-based classification is essential to promote disorder-specific treatment. We have made a proposal for such a classification incorporating the cognitive domains.

Language in the aging brain: the network dynamics of cognitive decline and preservation.

Language is a crucial and complex lifelong faculty, underpinned by dynamic interactions within and between specialized brain networks. Whereas normal aging impairs specific aspects of language production, most core language processes are robust to brain aging. We review recent behavioral and neuroimaging evidence showing that language systems remain largely stable across the life span and that both younger and older adults depend on dynamic neural responses to linguistic demands. Although some aspects of network dynamics change with age, there is no consistent evidence that core language processes are underpinned by different neural networks in younger and older adults.

IKKβ deficiency in myeloid cells ameliorates Alzheimer's disease-related symptoms and pathology.

Alzheimer's disease (AD) is characterized by extracellular amyloid-β (Aβ) deposits and microglia-dominated inflammatory activation. Innate immune signaling controls microglial inflammatory activities and Aβ clearance. However, studies examining innate immunity in Aβ pathology and neuronal degeneration have produced conflicting results. In this study, we investigated the pathogenic role of innate immunity in AD by ablating a key signaling molecule, IKKβ, specifically in the myeloid cells of TgCRND8 APP-transgenic mice. Deficiency of IKKβ in myeloid cells, especially microglia, simultaneously reduced inflammatory activation and Aβ load in the brain and these effects were associated with reduction of cognitive deficits and preservation of synaptic structure proteins. IKKβ deficiency enhanced microglial recruitment to Aβ deposits and facilitated Aβ internalization, perhaps by inhibiting TGF-β-SMAD2/3 signaling, but did not affect Aβ production and efflux. Therefore, inhibition of IKKβ signaling in myeloid cells improves cognitive functions in AD mice by reducing inflammatory activation and enhancing Aβ clearance. These results contribute to a better understanding of AD pathogenesis and could offer a new therapeutic option for delaying AD progression.

Effects of spending time outdoors in daylight on the psychosocial well-being of older people and their family carers: a systematic review

BACKGROUND A range of studies found that spending time outdoors in daylight provided substantial benefits for the psychosocial well-being of older people. Good psychosocial well-being is essential in maintaining overall health as people age and often contributes to adequate physical functioning. OBJECTIVES The overall objective of this study was to undertake a systematic review on the effects of spending time outdoors in daylight on the psychosocial well-being of older people and their family carers. INCLUSION CRITERIA Types of participants: This review considered studies that included older people aged 55 years or more, including those living in a community or residential accommodation setting. In addition, this review considered family carers, who were defined as unpaid relatives or friends of an older person, who helped that individual with their activities of daily living. Types of intervention(s): The intervention of interest was spending time outdoors in daylight. Types of studies: All experimental and epidemiological study designs including randomized controlled trials and non-randomized controlled trials published in the English language were included in this review. Types of outcomes: This review considered studies that included objective and/or subjective measures of psychosocial well-being for older people and their family carers. SEARCH STRATEGY The search aimed to find published and unpublished studies through electronic databases, reference lists, key reports and the World Wide Web. An extensive search was undertaken for the following databases: MEDLINE, CINAHL, Wiley Online Library, ProQuest Central, Scopus, and the Cochrane Library. Databases were searched up to December 2013. METHODOLOGICAL QUALITY Methodological quality was assessed independently by three reviewers using the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) checklists. Disagreements that arose between the reviewers were resolved through discussion. DATA COLLECTION Quantitative data were extracted from papers included in the review using the standardized data extraction tool from JBI-MAStARI. The data was individually extracted by two reviewers. Disagreements that arose between the reviewers were resolved through discussion. All results were subject to double data entry. DATA SYNTHESIS For this review statistical pooling of the data was not possible due to the heterogeneity of the studies; therefore, the findings are presented in narrative form. RESULTS A total of 13 studies were included in the final review. In the four studies that evaluated the effects of exposure to daylight on behavioral disturbances, there was no evidence of effect of daylight hours on physical and verbal aggression. There was some evidence to indicate that exposure to daylight for a period of time resulted in fewer depressive symptoms. Increasing the frequency of going outdoors was associated with better cognitive preservation over a one year period. Similarly exposure to daylight resulted in improved social functioning and improved quality of life. There were no studies that evaluated the effect of spending time outdoors in daylight on the psychosocial well-being of family carers, including carer satisfaction or carer stress. CONCLUSIONS There is insufficient high-quality evidence from which conclusions can be drawn for the effect of spending time outdoors in daylight on the psychosocial TRUNCATED AT 500 WORDS

Designing therapeutic clinical trials for older and frail adults with cancer: U13 conference recommendations.

A majority of cancer diagnoses and deaths occur in patients age ≥ 65 years. With the aging of the US population, the number of older adults with cancer will grow. Although the coming wave of older patients with cancer was anticipated in the early 1980s, when the need for more research on the cancer-aging interface was recognized, many knowledge gaps remain when it comes to treating older and/or frailer patients with cancer. Relatively little is known about the best way to balance the risks and benefits of existing cancer therapies in older patients; however, these patients continue to be underrepresented in clinical trials. Furthermore, the available clinical trials often do not include end points pertinent to the older adult population, such as preservation of function, cognition, and independence. As part of its ongoing effort to advance research in the field of geriatric oncology, the Cancer and Aging Research Group held a conference in November 2012 in collaboration with the National Cancer Institute, the National Institute on Aging, and the Alliance for Clinical Trials in Oncology. The goal was to develop recommendations and establish research guidelines for the design and implementation of therapeutic clinical trials for older and/or frail adults. The conference sought to identify knowledge gaps in cancer clinical trials for older adults and propose clinical trial designs to fill these gaps. The ultimate goal of this conference series is to develop research that will lead to evidence-based care for older and/or frail adults with cancer.

Functional correlates of cognitive dysfunction in multiple sclerosis: A multicenter fMRI Study.

In this multicenter study, we applied functional magnetic resonance imaging (fMRI) to define the functional correlates of cognitive dysfunction in patients with multiple sclerosis (MS). fMRI scans during the performance of the N-back task were acquired from 42 right-handed relapsing remitting (RR) MS patients and 52 sex-matched right-handed healthy controls, studied at six European sites using 3.0 Tesla scanners. Patients with at least two abnormal (<2 standard deviations from the normative values) neuropsychological tests at a standardized evaluation were considered cognitively impaired (CI). FMRI data were analyzed using the SPM8 software, modeling regions showing load-dependent activations/deactivations with increasing task difficulty. Twenty (47%) MS patients were CI. During the N-back load condition, compared to controls and CI patients, cognitively preserved (CP) patients had increased recruitment of the right dorsolateral prefrontal cortex. As a function of increasing task difficulty, CI MS patients had reduced activations of several areas located in the fronto-parieto-temporal lobes as well as reduced deactivations of regions which are part of the default mode network compared to the other two groups. Significant correlations were found between abnormal fMRI patterns of activations and deactivations and behavioral measures, cognitive performance, and brain T2 and T1 lesion volumes. This multicenter study supports the theory that a preserved fMRI activity of the frontal lobe is associated with a better cognitive profile in MS patients. It also indicates the feasibility of fMRI to monitor disease evolution and treatment effects in future studies.

Type 2 diabetes as a risk factor for cognitive impairment: current insights.

Type 2 diabetes mellitus (T2DM) is a risk factor for cognitive dysfunction and dementia in the elderly. T2DM has been thought to be associated with vascular diseases, eventually leading to vascular dementia, but recent studies have established that T2DM is also associated with Alzheimer’s disease (AD). With the increase in the number of elderly individuals with T2DM, the number of diabetic patients with cognitive dysfunction has been increasing. T2DM may accelerate AD-associated pathologies through insulin resistance. Vascular pathologies may also be associated with cognitive dysfunction and dementia in T2DM subjects. Several other mechanisms also seem to be involved in T2DM-related cognitive dysfunction. More investigations to clarify the association of T2DM with cognitive impairment are warranted. These investigations may help to increase our understanding of AD and open a new door to the development of therapeutics. Recent pharmaceutical advancement in T2DM treatment has resulted in the availability of a wide range of antidiabetics. Some evidence has suggested that antidiabetic therapies help to prevent cognitive dysfunction. At present, however, the optimal level of blood glucose control and the best combination of medications to achieve it in terms of cognitive preservation have not been established. More investigation is warranted. Cognitive dysfunction is an emerging new complication of T2DM that requires further study.

Posterior brain damage and cognitive impairment in pediatric multiple sclerosis

We combined structural and functional MRI to better understand the mechanisms responsible for cognitive impairment in pediatric patients with multiple sclerosis (MS). Brain dual-echo, diffusion tensor, 3D T1-weighted, and resting-state (RS) fMRI scans were acquired from 35 consecutive pediatric patients with MS and 16 sex- and age-matched healthy controls. Patients with abnormalities in ≥2 neuropsychological tests were classified as cognitively impaired. The regional distribution of white matter (WM) and gray matter (GM) damage was assessed using voxel-wise analyses. Default mode network (DMN) RS functional connectivity (FC) was also measured. Sixteen patients (45%) were classified as cognitively impaired. Compared to cognitively preserved (CP) patients, cognitively impaired patients with MS had higher occurrence of T2 lesions as well as more severe damage to the WM and GM, as measured by atrophy and diffusivity abnormalities, in the posterior regions of the parietal lobes close to the midline (precuneus, posterior cingulum, and corpus callosum). Compared to the other study groups, they also showed reduced RS FC of the precuneus, whereas CP patients experienced an increased RS FC of the anterior cingulate cortex. A multivariable model identified diffusivity abnormalities of the cingulum and corpus callosum and RS FC of the precuneus as the covariates more strongly associated with cognitive impairment (C-index = 0.99). In pediatric patients with MS, cognitive dysfunction is associated with structural and functional abnormalities of the posterior core regions of the DMN. WM structural abnormalities co-occurring at this level are likely to be the substrate of such modifications.

REST and stress resistance in ageing and Alzheimer’s disease

SummaryHuman neurons are functional over an entire lifetime, yet the mechanisms that preserve function and protect against neurodegeneration during aging are unknown. Here we show that induction of the repressor element 1-silencing transcription/neuron-restrictive silencer factor (REST/NRSF) is a universal feature of normal aging in human cortical and hippocampal neurons. REST is lost, however, in mild cognitive impairment (MCI) and Alzheimer’s disease (AD). Chromatin immunoprecipitation with deep sequencing (ChIP-seq) and expression analysis show that REST represses genes that promote cell death and AD pathology, and induces the expression of stress response genes. Moreover, REST potently protects neurons from oxidative stress and amyloid β-protein (Aβ) toxicity, and conditional deletion of REST in the mouse brain leads to age-related neurodegeneration. A functional ortholog of REST, C. elegans SPR-4, also protects against oxidative stress and Aβ toxicity. During normal aging, REST is induced in part by cell non-autonomous Wnt signaling. However, in AD, frontotemporal dementia and dementia with Lewy bodies, REST is lost from the nucleus and appears in autophagosomes together with pathologic misfolded proteins. Finally, REST levels during aging are closely correlated with cognitive preservation and longevity. Thus, the activation state of REST may distinguish neuroprotection from neurodegeneration in the aging brain.

Reducing late effects of radiotherapy in average risk medulloblastoma.

To assess the efficacy and safety in average-risk pediatric medulloblastoma (MB) receiving tumor bed boost irradiation compared to a posterior fossa (PF) boost. Thirty patients were enrolled in the study and divided evenly into two treatment arms of 15. Both arms received 23.4 Gy craniospinal irradiation (CS) and a 32.4 Gy boost. Patients in arm 1 were given PF boosts, and those in arm 2 were given boosts to the gross target volume (GTV). Weekly oncovin was given throughout all radiotherapy (RT). Eight cycles of adjuvant chemotherapy of CCNU, oncovin and platinol were given to all patients after RT. MRI, pure tone audiogram (PTA) and intelligence quotient (IQ) tests were performed before and after RT and every three months thereafter. There were significant differences in the sparing dose to the cochlea and brain stem as well as the volume of the normal brain receiving a 100% dose. There was a significant initial improvement of hearing function in patients given the target volume boost after RT, which was lost after chemotherapy. With a median follow up of 23 months, there was no difference in progression free survival or overall survival between the two arms. Irradiation of the tumor bed after 23.4 Gy craniospinal irradiation for average-risk MB results in similar disease control as a PF boost. Dosimetric sparing for the cochleae and normal tissue is evident in patients receiving tumor bed boosts. The hearing improvement and cognitive function preservation effects of the treatment need more follow up.

A protective factor for the ageing brain

What guards the aged brain against neurodegeneration? A study finds that the REST protein has a central role in protecting ageing neurons from death and in maintaining cognitive capacity in the elderly. See Article p.448 Age is the biggest risk factor for neurodegenerative disease. But why do some age with cognitive function intact, yet others decline and develop Alzheimer's disease? Here Bruce Yankner and colleagues show that during ageing, a protein known as REST (repressor element 1-silencing transcription factor, also called NRSF) is increasingly expressed in human cortical and hippocampal neurons. REST levels are strongly correlated with cognitive preservation and longevity. REST represses genes that promote cell death and Alzheimer's disease pathology and induces those that mediate the stress response. Moreover, REST protects neurons from oxidative stress and amyloid β-protein toxicity. Deleting REST from the mouse brain results in age-related neuronal cell death. And, in humans with mild cognitive impairment or Alzheimer's disease, REST is excluded from the nucleus in neurons, and this exclusion is associated with autophagy and misfolded proteins. This work suggests that the activation state of REST may distinguish neuroprotection from neurodegeneration in the ageing brain.