Safety and Acceptability of the Research Lumbar Puncture

Cerebrospinal fluid diagnostics in first-episode schizophrenia

We evaluated the clinical use and the safety of cerebrospinal fluid diagnostics in 155 patients with the suspected diagnosis of first-episode schizophrenia. Five patients (3.2%) revealed pathological findings that lead to diagnostic re-evaluation and changes in clinical management. No serious adverse events occurred, but we documented 16 (10.3%) cases of mild to moderate headache or local pain at the puncture site. Our results underline the value of lumbar puncture in the clinical workup of first-episode patients with suspected schizophrenia.

Consensus Guidelines for CSF and Blood Biobanking for CNS Biomarker Studies

There is a long history of research into body fluid biomarkers in neurodegenerative and neuroinflammatory diseases. However, only a few biomarkers in cerebrospinal fluid (CSF) are being used in clinical practice. Anti-aquaporin-4 antibodies in serum are currently useful for the diagnosis of neuromyelitis optica (NMO), but we could expect novel CSF biomarkers that help define prognosis and response to treatment for this disease. One of the most critical factors in biomarker research is the inadequate powering of studies performed by single centers. Collaboration between investigators is needed to establish large biobanks of well-defined samples. A key issue in collaboration is to establish standardized protocols for biobanking to ensure that the statistical power gained by increasing the numbers of CSF samples is not compromised by pre-analytical factors. Here, consensus guidelines for CSF collection and biobanking are presented, based on the guidelines that have been published by the BioMS-eu network for CSF biomarker research. We focussed on CSF collection procedures, pre-analytical factors and high quality clinical and paraclinical information. Importantly, the biobanking protocols are applicable for CSF biobanks for research targeting any neurological disease.

Evaluating the reliability of anatomic landmarks in safe lumbar puncture using magnetic resonance imaging: does sex matter?

Aim. To determine the level of the conus medullaris-Tuffier's line, and conus medullaris-Tuffier's line distance using imaging and evaluate their relation to age and gender. Methods. We performed a cross-sectional study of 189 adult participants, who underwent MR imaging of lumbosacral spine. Each vertebra was divided into 3 equal segments (upper, middle, and lower), and intervertebral disc space was also assumed as one segment. All segments from T12 upper segment to L5S1 intervertebral disc were numbered consecutively. The position of conus medullaris and Tuffier's line was determined by the vertebral segment or intervertebral disc space at the same level. The patients were stratified into high/low conus medullaris position (cutpoint: L1 middle segment) and short/long conus-Tuffier's distance (cutpoint: 14 segments). Results. Women with low conus were significantly more than men, in patients older than 50 years old (72.7% in females versus 55.3% in males; P < .05), whereas there was not such a sexual dimorphism in patients younger than 50 years old. Similarly, short conus-Tuffier's distance was more frequent among women than men in patients older than 50 years old (59.7% in females versus 39.5% in males; P < .05), whereas there was not any gender difference in patients younger than 50 years old. Conus-Tuffier's distance was negatively correlated with age (r = −0.32, P < .001) in all studied population. Conclusion. Anatomical landmarks vary according to age and gender, with a lower end of conus medullaris in women, so clinicians should use more caution on the identification of the appropriate site for lumbar puncture, particularly in elderly women.

What we worry about when we worry about the ethics of clinical research

Clinical research is thought to be ethically problematic and is subject to extensive regulation and oversight. Despite frequent endorsement of this view, there has been almost no systematic evaluation of why clinical research might be ethically problematic. As a result, it is difficult to determine whether the regulations to which clinical research is subject address the ethical concerns it raises. Commentators who consider this question at all tend to assume that clinical research is ethically problematic because it exposes some individuals to risks for the benefit of others. Yet, many other activities that expose some individuals to risks for the benefit of others are not subject to extensive regulation and oversight. This difference raises the question of whether clinical research is distinct from these activities in normatively relevant ways and, if so, what implications this difference (or differences) has for how clinical research should be regulated and conducted. The present manuscript attempts to answer this question by comparing clinical research to two other activities that expose some individuals to risks for the benefit of others. This comparison highlights an aspect of clinical research which has received relatively little attention, namely, the active role investigators play in exposing subjects to risks. I argue that this aspect explains much of the ethical concern expressed regarding clinical research. I end by considering the normative significance of this feature and the implications it has for how clinical research should be regulated and conducted.

CSF biomarkers in neurodegenerative diseases

Neurodegenerative diseases are major world wide causes of morbidity and mortality. They form a heterogeneous group of diseases, ranging from rare monogenic inherited errors of metabolism to common multi-factorial dementias. Major research efforts focus on the development of disease modifying drugs for neurodegenerative diseases. As a result, there follows a need for reliable tools for diagnosis, prognosis and monitoring of therapy. Processes in the brain can be monitored by analysis of cerebrospinal fluid (CSF). Several CSF biomarkers of pathological processes in the brain are now available. Such biomarkers may be used for both research and in the clinical setting. However, several difficult problems remain to be solved. More intensive collaboration between academia, industry and government is likely needed to develop treatments and biomarkers for neurodegenerative diseases. This article reviews the definitions, usage and current limitations of CSF biomarkers in this field.

Amyloid precursor protein (APP) processing genes and cerebrospinal fluid APP cleavage product levels in Alzheimer's disease

The aim of this exploratory investigation was to determine if genetic variation within amyloid precursor protein (APP) or its processing enzymes correlates with APP cleavage product levels: APPα, APPβ or Aβ42, in cerebrospinal fluid (CSF) of cognitively normal subjects or Alzheimer's disease (AD) patients. Cognitively normal control subjects (n = 170) and AD patients (n = 92) were genotyped for 19 putative regulatory tagging SNPs within 9 genes (APP, ADAM10, BACE1, BACE2, PSEN1, PSEN2, PEN2, NCSTN and APH1B) involved in the APP processing pathway. SNP genotypes were tested for their association with CSF APPα, APPβ, and Aβ42, AD risk and age-at-onset while taking into account age, gender, race and APOE ε4. After adjusting for multiple comparisons, a significant association was found between ADAM10 SNP rs514049 and APPα levels. In controls, the rs514049 CC genotype had higher APPα levels than the CA, AA collapsed genotype, whereas the opposite effect was seen in AD patients. These results suggest that genetic variation within ADAM10, an APP processing gene, influences CSF APPα levels in an AD specific manner.

Neuroinflammation Screening in Immunotherapy Trials against Alzheimer's Disease

Due to side effects in the form of meningoencephalitis in the interrupted phase II AN1792 trial of active antiamyloid β(Aβ) immunization against Alzheimer's disease (AD), there has been concern that anti-Aβ immunization may cause destructive neuroinflammation. Here, we report on two patients fulfilling clinical AD criteria who were diagnosed with Lyme neuroborreliosis during screening before inclusion in anti-Aβ immunotherapy trials. The two cases illustrate the necessity of careful biochemical screening for neuroinflammatory/neuroinfectious conditions before an AD diagnosis is made and before clinical AD patients are included in trials of therapy that could impact the immune system. Should the two cases have been included and deteriorated, additional investigations might have led to the erroneous conclusion that therapy-induced meningoencephalitis had occurred.

[Alzheimer's and related diseases: toward earlier and more accurate diagnosis]

Because of population ageing, the prevalence of Alzheimer's disease (AD), the most common cause of dementia, increases progressively. This condition is now considered as a public health priority. New disease modifying therapeutic strategies could be available in the next few years that would necessitate an accurate and early diagnosis of the disease. Recently developed diagnostic tools are being assessed. Development of structural brain imaging allows to measure the hippocampus volume. Metabolic imaging can assess a broad range of functional parameters such as cerebral blood flow and dopaminergic activity with single photon emission computed tomography, cerebral glucose metabolism and cerebral amyloid burden with positron emission tomography. Those imaging methods are under evaluation to appreciate cerebral abnormalities that may occur earlier than structural ones. Cerebrospinal fluid biomarkers, in particular amyloid and tau peptides, allow us to look at in vivo biochemical cerebral changes related to AD, before possible serum biomarkers. Studies are under way to confirm the relevance of these new diagnostic tools. It will help us to improve evaluation of patients with AD or related diseases.

Quantification of α-synuclein in cerebrospinal fluid as a biomarker candidate: review of the literature and considerations for future studies

The pursuit of laboratory tests that allow for the reliable and inexpensive identification of subjects with parkinsonism represents a hot topic in translational neuroscience. This unmet need affects the counseling of presymptomatic, at-risk subjects and delays the accurate diagnosis of already symptomatic individuals. The absence of validated markers that are closely linked to the pathological disease process also compromises the objective monitoring of therapeutic interventions in clinical trials. Typical Parkinson’s disease represents a heterogenous syndrome (but the majority of patients suffer from neurodegeneration) that is linked to the misprocessing of α-synuclein (α-Syn). The identification of α-Syn as a bona fide constituent of human cerebrospinal fluid and its quantification in early cross-sectional studies represent the beginning of a new chapter in Parkinson’s disease research. It will determine what role, if any, cerebrospinal fluid α-Syn plays as a biomarker candidate in Lewy inclusion-positive forms of parkinsonism. This article focuses on the progress that has been made in seven recently published papers and highlights the challenges that lie ahead. We also provide specific information regarding standardized operating procedures for cerebrospinal fluid collection in PD biomarker research efforts.

cNEUPRO: Novel Biomarkers for Neurodegenerative Diseases

“clinical NEUroPROteomics of neurodegenerative diseases” (cNEUPRO) is a Specific Targeted Research Project (STREP) within the sixth framework program of the European Commission dedicated to the search for novel biomarker candidates for Alzheimer's disease and other neurodegenerative diseases. The ultimate goal of cNEUPRO is to identify one or more valid biomarker(s) in blood and CSF applicable to support the early and differential diagnosis of dementia disorders. The consortium covers all steps required for the discovery of novel biomarker candidates such as acquisition of high quality CSF and blood samples from relevant patient groups and controls, analysis of body fluids by various methods, and finally assay development and assay validation. Here we report the standardized procedures for diagnosis and preanalytical sample-handling within the project, as well as the status of the ongoing research activities and some first results.

Biological markers and Alzheimer disease: a canadian perspective

Decreased β-amyloid_1-42 and increased phospho-tau protein levels in the cerebrospinal fluid (CSF) are currently the most accurate chemical neurodiagnostics of sporadic Alzheimer disease (AD). A report (2007) of the Third Canadian Consensus Conference on the Diagnosis and Treatment of Dementia (2006) recommended that biological markers should not be currently requisitioned by primary care physicians in the routine investigation of subjects with memory complaints. Consideration for such testing should prompt patient referral to a specialist engaged in dementia evaluations or a Memory Clinic. The specialist should consider having CSF biomarkers (β-amyloid_1-42 and phospho-tau) measured at a reputable facility in restricted cases presenting with atypical features and diagnostic confusion, but not as a routine procedure in all individuals with typical sporadic AD phenotypes. We submit that developments in the field of AD biomarker discovery since publication of the 3rd CCCDTD consensus data do not warrant revision of the 2007 recommendations.

Increased cerebrospinal fluid F2-isoprostanes are associated with aging and latent Alzheimer's disease as identified by biomarkers

Alzheimer's disease (AD) is a common age-related chronic illness with latent, prodrome, and fully symptomatic dementia stages. Increased free radical injury to regions of brain is one feature of prodrome and dementia stages of AD; however, it also is associated with advancing age. This raises the possibility that age-related free radical injury to brain might be caused in part or in full by latent AD. We quantified free radical injury in the central nervous system with cerebrospinal fluid (CSF) F(2)-isoprostanes (IsoPs) in 421 clinically normal individuals and observed a significant increase over the adult human lifespan (P < 0.001). Using CSF amyloid (A) β(42) and tau, we defined normality using results from 28 clinically normal individuals <50 years old, and then stratified 74 clinically normal subjects ≥60 years into those with CSF that had normal CSF Aβ(42) and tau (n = 37); abnormal CSF Aβ(42) and tau, the biomarker signature of AD (n = 24); decreased Aβ(42) only (n = 4); or increased tau only (n = 9). Increased CSF F(2)-IsoPs were present in clinically normal subjects with the biomarker signature of AD (P < 0.05) and those subjects with increased CSF tau (P < 0.001). Finally, we analyzed the relationship between age and CSF F(2)-IsoPs for those clinically normal adults with normal CSF (n = 37) and those with abnormal CSF Aβ(42) and/or tau (n = 37); only those with normal CSF demonstrated a significant increase with age (P < 0.01). These results show that CSF F(2)-IsoPs increased across the human lifespan and that this age-related increase in free radical injury to brain persisted after culling those with laboratory evidence of latent AD.

Biomarkers for Alzheimer's disease: academic, industry and regulatory perspectives

Advances in therapeutic strategies for Alzheimer's disease that lead to even small delays in onset and progression of the condition would significantly reduce the global burden of the disease. To effectively test compounds for Alzheimer's disease and bring therapy to individuals as early as possible there is an urgent need for collaboration between academic institutions, industry and regulatory organizations for the establishment of standards and networks for the identification and qualification of biological marker candidates. Biomarkers are needed to monitor drug safety, to identify individuals who are most likely to respond to specific treatments, to stratify presymptomatic patients and to quantify the benefits of treatments. Biomarkers that achieve these characteristics should enable objective business decisions in portfolio management and facilitate regulatory approval of new therapies.

Cerebrospinal fluid analysis should be considered in patients with cognitive problems

Hepatologists assay liver enzymes and cardiologists structural heart proteins in serum to diagnose and monitor their patients. This way of thinking has not quite made it into the memory clinics yet, in spite of the availability of validated cerebrospinal fluid biomarkers for key pathological events in the brain in neurodegeneration. Here, we argue that a spinal tap should be considered in all patients who seek medical advice for memory problems and list the highly relevant clinical questions CSF analyses can address.

Cerebrospinal fluid abnormalities and rate of decline in everyday function across the dementia spectrum: normal aging, mild cognitive impairment, and Alzheimer disease

OBJECTIVE

To investigate the effect of cerebrospinal fluid (CSF) abnormalities on the rate of decline in everyday function in normal aging, mild cognitive impairment (MCI), and mild Alzheimer disease (AD).

DESIGN

Immunoassays of total tau (t-tau), tau phosphorylated at threonine 181 (p-tau(181)), and beta-amyloid 1-42 (Abeta(42)) concentrations were performed in CSF obtained from participants in the Alzheimer's Disease Neuroimaging Initiative. Random effects regressions were used to examine the relationship among CSF abnormalities, cognitive impairment (assessed with the Alzheimer Disease Assessment Scale-cognitive subscale [ADAS-Cog]), and functional decline (assessed with the Pfeffer Functional Activities Questionnaire) and to determine whether the impact of CSF abnormalities on functional decline is mediated by cognitive impairment.

SETTING

Fifty-eight sites in the United States and Canada.

PARTICIPANTS

One hundred fourteen cognitively intact adults, 195 patients with MCI, and 100 patients with mild AD. Main Outcome Measure Decline in the Pfeffer Functional Activities Questionnaire score.

RESULTS

Abnormalities in all CSF analytes were associated with functional decline in MCI, and all but the t-tau:Abeta(42) ratio were associated with functional decline in controls. No abnormal CSF analyte was associated with functional decline in AD. Among controls, p-tau(181) concentration was the most sensitive to functional decline, whereas in MCI it was Abeta(42) concentration. Cerebrospinal fluid biomarkers were uniformly more sensitive to functional decline than the ADAS-Cog score among controls and variably so in MCI, whereas the ADAS-Cog score was unequivocally more sensitive than CSF biomarkers in AD. The impact of CSF abnormalities on functional decline in MCI was partially mediated by their effect on cognitive status. Across all diagnostic groups, persons with both tau and Abeta(42) abnormalities exhibited the steepest rate of functional decline.

CONCLUSIONS

Abnormalities in CSF are associated with functional decline and thus with future development of AD in controls and patients with MCI. However, they do not predict further functional degradation in patients with AD. Persons with comorbid tau and Abeta(42) abnormalities are at greatest risk of functional loss.

To know or not to know: ethical issues related to early diagnosis of Alzheimer's disease

In Alzheimer's disease (AD), pathological processes start in the brain long before clinical dementia. Biomarkers reflecting brain alterations may therefore indicate disease at an early stage, enabling early diagnosis. This raises several ethical questions and the potential benefits of early diagnosis must be weighted against possible disadvantages. Currently, there are few strong arguments favouring early diagnosis, due to the lack of disease modifying therapy. Also, available diagnostic methods risk erroneous classifications, with potentially grave consequences. However, a possible benefit of early diagnosis even without disease modifying therapy is that it may enable early decision making when patients still have full decision competence, avoiding problems of hypothetical consents. It may also help identifying patients with cognitive dysfunction secondary to other diseases that may be responsive to treatment already today.

Aspects of beta-amyloid as a biomarker for Alzheimer's disease

Alzheimer's disease is an age-related neurodegenerative disorder that results in progressive cognitive impairment and death. The accumulation of beta-amyloid (Abeta) in specific brain regions is believed by many to represent the earliest event in the pathogenesis of the disease. Here, we review the key aspects of Abeta as a biomarker for Alzheimer's disease, including the pathogenicity of Abeta, the possible biological functions of its precursor protein, the Abeta metabolism and homeostasis, the diagnostic performance of different Abeta assays in different settings and the potential usefulness of Abeta as a surrogate marker for treatment efficacy in clinical trials of novel Abeta-targeting drugs against Alzheimer's disease.

Cerebrospinal Fluid Biomarkers in Diagnosing Alzheimer's Disease in Clinical Practice: An Illustration with 3 Case Reports

Analysis of the brain specific biomarkers amyloid β₄₂ (Aβ₄₂) and total tau (t-tau) protein in cerebrospinal fluid (CSF) has a sensitivity and specificity of more than 85% for differentiating Alzheimer's Disease (AD) from non-demented controls. International guidelines are contradictory in their advice on the use of CSF biomarkers in AD diagnostics, resulting in a lack of consistency in clinical practice. We present three case reports that illustrate clinical practice according to the Dutch and European guidelines and portray the value of CSF biomarker analysis as an add-on diagnostic to the standard diagnostic workup for AD.

Imaging and biomarkers for Alzheimer's disease

The development of acetyl-cholinesterase inhibitors, and the prospect of future therapies to prevent, or modify, the course of Alzheimer's disease necessitates greater accuracy in diagnosis of this heterogeneous disease. Current diagnosis is based on clinical criteria and neuropathology. This is not always sufficient, and the development of sensitive and specific biomarkers would enable earlier and more accurate diagnosis. Genetic markers, such as Apolipoprotein E4, and cerebrospinal fluid markers such as beta-amyloid and tau, support a diagnosis of Alzheimer's disease. The latter can also predict conversion from mild cognitive impairment to dementia. Imaging markers improve diagnostic accuracy by reflecting brain function or aspects of in vivo pathological changes. In order for such biomarkers to become clinically useful, however, effective treatments need to become available, and long-term follow-up studies are necessary to evaluate the relevance of cross-sectional biomarker changes for the longitudinal natural history of the disease.

A consensus protocol for the standardization of cerebrospinal fluid collection and biobanking

There is a long history of research into body fluid biomarkers in neurodegenerative and neuroinflammatory diseases. However, only a few biomarkers in CSF are being used in clinical practice. One of the most critical factors in CSF biomarker research is the inadequate powering of studies because of the lack of sufficient samples that can be obtained in single-center studies. Therefore, collaboration between investigators is needed to establish large biobanks of well-defined samples. Standardized protocols for biobanking are a prerequisite to ensure that the statistical power gained by increasing the numbers of CSF samples is not compromised by preanalytical factors. Here, a consensus report on recommendations for CSF collection and biobanking is presented, formed by the BioMS-eu network for CSF biomarker research in multiple sclerosis. We focus on CSF collection procedures, preanalytical factors, and high-quality clinical and paraclinical information. The biobanking protocols are applicable for CSF biobanks for research targeting any neurologic disease.

Neurochemical biomarkers in the differential diagnosis of movement disorders

In recent years, the neurochemical analysis of neuronal proteins in cerebrospinal fluid (CSF) has become increasingly accepted for the diagnosis of neurodegenerative dementia diseases such as Alzheimer's disease and Creutzfeldt-Jakob disease. CSF surrounds the central nervous system, and in the composition of CSF proteins one finds brain-specific proteins that are prioritized from blood-derived proteins. Levels of specific CSF proteins could be very promising biomarkers for central nervous system diseases. We need the development of more easily accessible biomarkers, in the blood. In neurodegenerative diseases with and without dementia, studies on CSF and blood proteins have investigated the usefulness of biomarkers in differential diagnosis. The clinical diagnoses of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration still rely mainly on clinical symptoms as defined by international classification criteria. In this article, we review CSF biomarkers in these movement disorders and discuss recent published reports on the neurochemical intra vitam diagnosis of neurodegenerative disorders (including recent CSF alpha-synuclein findings).

Total and phosphorylated tau protein as biological markers of Alzheimer's disease

Advances in our understanding of tau-mediated neurodegeneration in Alzheimer's disease (AD) are moving this disease pathway to center stage for the development of biomarkers and disease modifying drug discovery efforts. Immunoassays were developed detecting total (t-tau) and tau phosphorylated at specific epitopes (p-tauX) in cerebrospinal fluid (CSF), methods to analyse tau in blood are at the experimental beginning. Clinical research consistently demonstrated CSF t- and p-tau increased in AD compared to controls. Measuring these tau species proved informative for classifying AD from relevant differential diagnoses. Tau phosphorylated at threonine 231 (p-tau231) differentiated between AD and frontotemporal dementia, tau phosphorylated at serine 181 (p-tau181) enhanced classification between AD and dementia with Lewy bodies. T- and p-tau are considered "core" AD biomarkers that have been successfully validated by controlled large-scale multi-center studies. Tau biomarkers are implemented in clinical trials to reflect biological activity, mechanisms of action of compounds, support enrichment of target populations, provide endpoints for proof-of-concept and confirmatory trials on disease modification. World-wide quality control initiatives are underway to set required methodological and protocol standards. Discussions with regulatory authorities gain momentum defining the role of tau biomarkers for trial designs and how they may be further qualified for surrogate marker status.

Safety of lumbar puncture procedures in patients with Alzheimer's disease

Changes in cerebrospinal fluid (CSF) biomarkers are representative of biochemical changes in the brain. Collection of CSF by lumbar puncture (LP) is essential for biomarker analysis, which is important for research in neurodegenerative disorders. However, LP for research purposes has been controversial due to a reported high incidence of severe LP headache when using standard 18g or 20g Quincke needles with a beveled cutting tip. A procedural safety analysis was performed using the database of a multicenter, 13-week study of CSF cholinesterase activity. A 24g Sprotte atraumatic needle was used to collect CSF at baseline and at Week 13 from 63 older patients with mild to moderate Alzheimer's disease. There was a < 2% LP headache incidence, and a favorable safety profile was reported. In conclusion, LP performed with a 24g Sprotte atraumatic needle (blunt, "bullet" tip) was a well tolerated procedure, with good acceptability.

Factors associated with traumatic fluoroscopy-guided lumbar punctures: a retrospective review

BACKGROUND AND PURPOSE

To minimize diagnostic confusion, a CSF specimen should be free from traumatically introduced red blood cells (RBCs). The purpose of this research is to determine if patient age, sex, gauge of the lumbar puncture (LP) needle, or the level of LP is associated with an increased risk for traumatic fluoroscopy-guided LP.

MATERIALS AND METHODS

Data were collected retrospectively for consecutive male and female patients of all ages (n = 756) who underwent a fluoroscopy-guided LP for a 2-year period. We defined traumatic LP as a CSF sample with an RBC count more than 500 cells/mm(3) without xanthochromia.

RESULTS

Rate of traumatic LP was 13.3%. The rate of traumatic LP at the L4-L5 level (19%) was significantly higher than at the L2-L3 (9%) or L3-L4 level (10%). Patients older than 80 years had higher traumatic LP rates (25.9%) compared with patients between ages 11 and 80 years (12.4%). Sex and gauge of the spinal needle were not associated with increased rate of traumatic LP. Patients younger than 1 year had failed LP rate of 58.8% compared with 3.2% failure rate in older patients.

CONCLUSIONS

Fluoroscopy-guided LP at the L4-L5 level is associated with nearly twice the risk for traumatic puncture compared with the L2-L3 or L3-L4 level. Rates of traumatic result are twice as high in adults older than 80 years compared with younger patients. Failure rates for fluoroscopy-guided LP are low except in children younger than 1 year, in whom failure occurs in most cases.

Schizophrenia genomics and proteomics: are we any closer to biomarker discovery?

The field of proteomics has made leaps and bounds in the last 10 years particularly in the fields of oncology and cardiovascular medicine. In comparison, neuroproteomics is still playing catch up mainly due to the relative complexity of neurological disorders. Schizophrenia is one such disorder, believed to be the results of multiple factors both genetic and environmental. Affecting over 2 million people in the US alone, it has become a major clinical and public health concern worldwide. This paper gives an update of schizophrenia biomarker research as reviewed by Lakhan in 2006 and gives us a rundown of the progress made during the last two years. Several studies demonstrate the potential of cerebrospinal fluid as a source of neuro-specific biomarkers. Genetic association studies are making headway in identifying candidate genes for schizophrenia. In addition, metabonomics, bioinformatics, and neuroimaging techniques are aiming to complete the picture by filling in knowledge gaps. International cooperation in the form of genomics and protein databases and brain banks is facilitating research efforts. While none of the recent developments described here in qualifies as biomarker discovery, many are likely to be stepping stones towards that goal.

Cerebrospinal fluid: when is it worthwhile to do a lumbar puncture?

Clinicians should have an understanding of a lumbar puncture is indicated in the differential diagnosis of dementia and delirium. In most cases, this procedure is not commonly performed in outpatient practice for the differential diagnosis of dementia. However, in patients who have acute or subacute onset or a very rapid decline—such as in suspected Creutzfeldt-Jakob disease (CJD)—cerebrospinal fluid (CSF) 14-3-3, and tau proteins can be diagnostic for at least sporadic CJD. Practice parameters from the American Academy of Neurology (AAN) suggest performing a spinal tap on patients ≤55 years of age. However, that recommendation may not always be beneficial, particularly in a patient who has a prominent family history of either Alzheimer’s disease (AD) or frontotemporal dementia. Per the AAN practice parameter, lumbar puncture for CSF analysis is indicated in the diagnosis of central nervous system (CNS) infection, carcinomatous meningitis, or CNS vasculitis.

Beyond the clinically indicated lumbar puncture, there is utility of CSF biomarkers, including CSF Aβ42, total tau, and phospho-tau, which are the best studied. These biomarkers may be useful for cases involving atypical presentations of dementia, eg, when it is difficult to determine if the patient has AD versus frontotemporal dementia. They may be most useful for cases in which there is an atypical presentation of the fluorodeoxyglucose PET image or PET image features of both AD and frontotemporal dementia.

Biomarkers for cognitive impairment and dementia in elderly people

The threat of a looming pandemic of dementia in elderly people highlights the compelling need for the development and validation of biomarkers that can be used to identify pre-clinical and prodromal stages of disease in addition to fully symptomatic dementia. Although predictive risk factors and correlative neuroimaging measures will have important roles in these efforts, this Review describes recent progress in the discovery, validation, and standardisation of molecular biomarkers--small molecules and macromolecules whose concentration in the brain or biological fluids can aid diagnosis at different stages of the more common dementing diseases and in the assessment of disease progression and response to therapeutics. An approach that efficiently combines independent information from risk-factor assessment, neuroimaging measures, and biomarkers might soon guide clinicians in the early diagnosis and management of cognitive impairment in elderly people.

Free radical-mediated damage to brain in Alzheimer's disease and its transgenic mouse models

Advances in our understanding of the etiologies and pathogenesis of Alzheimer's disease (AD) highlight a role for free radical-mediated injury to brain regions from early stages of this illness. Here we will review the evidence from transgenic mouse models of AD, autopsy samples, and human biofluids obtained during life paying particular attention to the stage of disease. In addition, we will review the epidemiologic literature that addresses the potential of anti-oxidants to prevent incident dementia from AD, and the clinical trial literature that addresses anti-oxidant preventative or therapeutic strategies for different stage of AD. Future efforts in preclinical models and ultimately clinical trials are needed to define optimally effective agents and combinations, doses, and timing to suppress safely this facet of AD.

Clinical proteomics in neurodegenerative disorders

Neurodegenerative disorders are characterized by neuronal impairment that eventually leads to neuronal death. In spite of the brain's known capacity for regeneration, lost neurons are difficult to replace. Therefore, drugs aimed at inhibiting neurodegenerative processes are likely to be most effective if the treatment is initiated as early as possible. However, clinical manifestations in early disease stages are often numerous, subtle and difficult to diagnose. This is where biomarkers that specifically reflect onset of pathology, directly or indirectly, may have a profound impact on diagnosis making in the future. A triplet of biomarkers for Alzheimer's disease (AD), total and hyperphosphorylated tau and the 42 amino acid isoform of beta-amyloid, has already been established for early detection of AD before the onset of dementia. However, more biomarkers are needed both for AD and for other neurodegenerative disorders, such as Parkinson's disease, frontotemporal dementia and amyotrophic lateral sclerosis. This review provides an update on recent advances in clinical neuroproteomics, a biomarker discovery field that has expanded immensely during the last decade, and gives an overview of the most commonly used techniques and the major clinically relevant findings these techniques have lead to.

[Near a biological diagnosis of Alzheimer's disease and related disorders]

PURPOSE

To review the current concepts in the biological diagnosis of Alzheimer's disease (AD) and related disorders.

CURRENT KNOWLEDGE AND KEY POINTS

As new therapeutics specific of AD may be available soon, early diagnosis of AD in the context of mild cognitive impairment (MCI) or dementia appears to be challenging. The high amount of atypical clinical forms of AD leads to develop new tools allowing in vivo diagnosis. New CerebroSpinal Fluid (CSF) biomarkers seem to reflect specific aspects of deep neuropathological changes observed in AD, i.e. amyloid deposits and neurofibrillary tangles. Amyloid beta-peptide 1-42 (Abeta(1-42)) and hyperphosphorylated tubulin associated unit (tau) isoforms appear to be the most sensitive and specific CSF biomarkers, the combination of these biomarkers depicting the best diagnosis value for AD. These molecules are also efficient in the prediction of the conversion from the MCI state to the dementia state of AD. Combined to clinical and neuro-imaging information, CSF biomarkers appear thus to be highly relevant in improving the early etiological diagnosis of dementia.

FUTURE PROSPECTS AND PROJECTS

The current research focalises on the development of new molecules coming from Abeta and tau protein families, in the CSF and in the serum, as well as molecules reflecting other pathological metabolism changes, as alpha-synuclein in Lewy Body Disease. The diagnosis value of CSF biological markers is so promising that they have been recently included in the research diagnosis criteria of AD.

CSF multianalyte profile distinguishes Alzheimer and Parkinson diseases

The therapeutic imperative for Alzheimer disease (AD) and Parkinson disease (PD) calls for discovery and validation of biomarkers. Increased cerebrospinal fluid (CSF) tau and decreased amyloid (A) beta42 have been validated as biomarkers of AD. In contrast, there is no validated CSF biomarker for PD. We validated our proteomics-discovered multianalyte profile (MAP) in CSF from 95 control subjects, 48 patients with probable AD, and 40 patients with probable PD. An optimal 8-member MAP agreed with expert diagnosis for 90 control subjects (95%), 36 patients with probable AD (75%), and 38 patients with probable PD (95%). This MAP consisted of the following (in decreasing order of contribution): tau, brain-derived neurotrophic factor, interleukin 8, Abeta42, beta2-microglobulin, vitamin D binding protein, apolipoprotein (apo) AII, and apoE. This first large-scale validation of a proteomic-discovered MAP suggests a panel of 8 CSF proteins that are highly effective at identifying PD and moderately effective at identifying AD.

Biomarkers for Alzheimer's disease

The development and validation of biomarkers for the latent, prodromal and dementia stages of Alzheimer's disease (AD) is a pressing issue because of their high prevalence and an emerging set of experimental therapeutics that will soon force decisions regarding risk versus benefit. While genetic risk factors and neuroimaging will certainly have important roles to play, here we have focused on biomarkers assayed in body fluids. There is developing consensus for a central role for cerebrospinal fluid amyloid-beta (Abeta)42 and tau species to aid in the diagnosis of AD at different stages; plasma-based assays for Abeta species show some promise, but the picture is much less clear than in the cerebrospinal fluid. Biomarkers of different pathogenic steps thought to contribute to AD will also be important in assessing pharmacologic mechanisms of new therapies. Discovery approaches now underway may develop novel panels of biomarkers for AD. The next 5 years will see standardization of more established approaches, and the combination of different modalities into the most effective means for assessing different stages of AD.

Research criteria for the diagnosis of Alzheimer's disease: revising the NINCDS-ADRDA criteria

The NINCDS-ADRDA and the DSM-IV-TR criteria for Alzheimer's disease (AD) are the prevailing diagnostic standards in research; however, they have now fallen behind the unprecedented growth of scientific knowledge. Distinctive and reliable biomarkers of AD are now available through structural MRI, molecular neuroimaging with PET, and cerebrospinal fluid analyses. This progress provides the impetus for our proposal of revised diagnostic criteria for AD. Our framework was developed to capture both the earliest stages, before full-blown dementia, as well as the full spectrum of the illness. These new criteria are centred on a clinical core of early and significant episodic memory impairment. They stipulate that there must also be at least one or more abnormal biomarkers among structural neuroimaging with MRI, molecular neuroimaging with PET, and cerebrospinal fluid analysis of amyloid beta or tau proteins. The timeliness of these criteria is highlighted by the many drugs in development that are directed at changing pathogenesis, particularly at the production and clearance of amyloid beta as well as at the hyperphosphorylation state of tau. Validation studies in existing and prospective cohorts are needed to advance these criteria and optimise their sensitivity, specificity, and accuracy.

A combined dataset of human cerebrospinal fluid proteins identified by multi-dimensional chromatography and tandem mass spectrometry

Human cerebrospinal fluid (CSF) is an important source for studying protein biomarkers of age-related neurodegenerative diseases. Before characterizing biomarkers unique to each disease, it is necessary to categorize CSF proteins systematically and extensively. However, the enormous complexity, great dynamic range of protein concentrations, and tremendous protein heterogeneity due to post-translational modification of CSF create significant challenges to the existing proteomics technologies for an in-depth, nonbiased profiling of the human CSF proteome. To circumvent these difficulties, in the last few years, we have utilized several different separation methodologies and mass spectrometric platforms that greatly enhanced the identification coverage and the depth of protein profiling of CSF to characterize CSF proteome. In total, 2594 proteins were identified in well-characterized pooled human CSF samples using stringent proteomics criteria. This report summarizes our efforts to comprehensively characterize the human CSF proteome to date.

Biomarkers in the diagnosis of Alzheimer's disease: are we ready?

Although clinical manifestations of cognitive dysfunction and impairments of activities of daily living are the current standard measures for the diagnosis of Alzheimer's disease, biomarkers are receiving increasing attention in research centers as possible early diagnostic measures or as surrogate measures of the ongoing pathology. In preparation for the upcoming development of the Diagnostic and Statistical Manual of Mental Disorders (5th ed; DSM-V) nosology, the American Psychiatric Association has sponsored an effort to reassess the current approaches to diagnosis in dementia in general and Alzheimer's disease in particular. This article focuses on the potential use of biomarkers in the diagnosis of Alzheimer's disease, in the monitoring of mild cognitive impairment, and as possible prognostic markers in normal controls at risk for dementia. Most advanced information is available with the biomarkers found in the cerebrospinal fluid, but there are many other potential biomarkers using blood, brain imaging, or a combination. The current biomarker approaches to diagnosis are reviewed along with a special emphasis on near-term recommendations and further research directions.

Biomarkers to advance drug development for Alzheimer’s disease

There is a sense of excitement and anticipation that drugs based on the β-amyloid hypothesis of Alzheimer’s disease (AD) may significantly reduce progression of the disease. However, without appropriate biomarkers, potentially effective drugs may actually fail to demonstrate efficacy owing to difficulties in choosing a proper dose and difficulty in detecting improved clinical outcomes in short trials. Both hypothesis- and discovery-based approaches, including high-throughput proteomic profiling, should be applied for discovery of biomarkers to better understand the action of novel therapies on their targets and on the molecular pathology of the disease. It is also imperative to identify antecedent markers, without which, patients with AD will be prescribed drugs that may prolong a life of slowly progressing dementia. Where we look for novel AD biomarkers and how we discover them is the subject of this perspective.