Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU): Trial Satisfaction and Attitudes towards Future Clinical Trials.

BACKGROUND: Clinical trial satisfaction is increasingly important for future trial designs and is associated with treatment adherence and willingness to enroll in future research studies or to recommend trial participation. In this post-trial survey, we examined participant satisfaction and attitudes toward future clinical trials in the Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU). METHODS: We developed an anonymous, participant satisfaction survey tailored to participants enrolled in the DIAN-TU-001 double-blind clinical trial of solanezumab or gantenerumab and requested that all study sites share the survey with their trial participants. A total of 194 participants enrolled in the trial at 24 study sites. We utilized regression analysis to explore the link between participants' clinical trial experiences, their satisfaction, and their willingness to participate in upcoming trials. RESULTS: Survey responses were received over a sixteen-month window during 2020-2021 from 58 participants representing 15 study sites. Notably, 96.5% of the survey respondents expressed high levels of satisfaction with the trial, 91.4% would recommend trial participation, and 96.5% were willing to enroll again. Age, gender, and education did not influence satisfaction levels. Participants reported enhanced medical care (70.7%) and pride in contributing to the DIAN-TU trial (84.5%). Satisfaction with personnel and procedures was high (98.3%). Respondents had a mean age of 48.7 years, with most being from North America and Western Europe, matching the trial's demographic distribution. Participants' decisions to learn their genetic status increased during the trial, and most participants endorsed considering future trial participation regardless of the DIAN-TU-001 trial outcome. CONCLUSION: Results suggest that DIAN-TU-001 participants who responded to the survey exhibited high motivation to participate in research, overall satisfaction with the clinical trial, and willingness to participate in research in the future, despite a long trial duration of 4-7 years with detailed annual clinical, cognitive, PET, MRI, and lumbar puncture assessments. Implementation of features that alleviate barriers and challenges to trial participation is like to have a high impact on trial satisfaction and reduce participant burden.

Effects of Vascular Risk Factors on the Association of Blood-Based Biomarkers with Alzheimer's Disease.

Background: Comorbidities may influence the levels of blood-based biomarkers for Alzheimer's disease (AD). We investigated whether differences in risk factors or comorbid conditions might explain the discordance between clinical diagnosis and biomarker classifications in a multi-ethnic cohort of elderly individuals. Aims: To evaluate the relationship of medical conditions and other characteristics, including body mass index (BMI), vascular risk factors, and head injury, with cognitive impairment and blood-based biomarkers of AD, phosphorylated tau (P-tau 181, P-tau 217), in a multi-ethnic cohort. Methods: Three-hundred individuals, aged 65 and older, were selected from a prospective community-based cohort for equal representation among three racial/ethnic groups: non-Hispanic White, Hispanic/Latino and African American/Black. Participants were classified into four groups based on absence (Asym) or presence (Sym) of cognitive impairment and low (NEG) or high (POS) P-tau 217 or P-tau 181 levels, determined previously in the same cohort: (Asym/NEG, Asym/POS, Sym/NEG, Sym/POS). We examined differences in individual characteristics across the four groups. We performed post-hoc analysis examining the differences across biomarker and cognitive status. Results: P-tau 217 or P-tau 181 positive individuals had lower BMI than P-tau negative participants, regardless of symptom status. Symptomatic and asymptomatic participants did not differ in terms of BMI. BMI was not a mediator of the effect of P-tau 217 or P-tau 181 on dementia. Frequencies of other risk factors did not differ between the four groups of individuals. Conclusions: Participants with higher levels of P-tau 217 or P-tau 181 consistent with AD had lower BMI regardless of whether the individual was symptomatic. These findings suggest that weight loss may change with AD biomarker levels before onset of cognitive decline. They do not support BMI as a confounding variable. Further longitudinal studies could explore the relationship of risk factors with clinical diagnoses and biomarkers.

Extracellular Tau Oligomers Produce An Immediate Impairment of LTP and Memory.

Non-fibrillar soluble oligomeric forms of amyloid-ß peptide (oAß) and tau proteins are likely to play a major role in Alzheimer's disease (AD). The prevailing hypothesis on the disease etiopathogenesis is that oAß initiates tau pathology that slowly spreads throughout the medial temporal cortex and neocortices independently of Aß, eventually leading to memory loss. Here we show that a brief exposure to extracellular recombinant human tau oligomers (oTau), but not monomers, produces an impairment of long-term potentiation (LTP) and memory, independent of the presence of high oAß levels. The impairment is immediate as it raises as soon as 20 min after exposure to the oligomers. These effects are reproduced either by oTau extracted from AD human specimens, or naturally produced in mice overexpressing human tau. Finally, we found that oTau could also act in combination with oAß to produce these effects, as sub-toxic doses of the two peptides combined lead to LTP and memory impairment. These findings provide a novel view of the effects of tau and Aß on memory loss, offering new therapeutic opportunities in the therapy of AD and other neurodegenerative diseases associated with Aß and tau pathology.

A Randomized, Double-Blind, Phase 2 Study of the Effects of the Vaccine Vanutide Cridificar with QS-21 Adjuvant on Immunogenicity, Safety and Amyloid Imaging in Patients with Mild to Moderate Alzheimer's Disease.

BACKGROUND: Vanutide Cridificar (ACC-001), a novel investigational immunotherapeutic vaccine designed to elicit antibodies against the N-terminal peptide 1-7 of the amyloid-beta peptide, believed to be important in the pathogenesis of Alzheimer's disease (AD). OBJECTIVES: To evaluate the immunogenicity, safety and impact of ACC-001 with Quillaja saponaria (QS-21) adjuvant on the reduction of brain fibrillar amyloid burden, assayed by positron emission tomography (PET) imaging, in patients with mild to moderate AD. DESIGN: Randomized, phase 2, interventional study. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01284387. PARTICIPANTS: Individuals with mild to moderate Alzheimer's disease (Mini-Mental State Examination scores 18-26; measurable amyloid burden in the expected range, on the screening 18F-florbetapir PET scan; and a Rosen modified Hachinski ischemic score ≤4). INTERVENTION: Participants were randomized to 3 µg or 10 µg ACC-001 (each in combination with 50 µg QS-21) or placebo (without QS-21). MEASUREMENTS: Primary endpoint was the change from baseline to week 104 in cerebral amyloid burden as measured by the global cortical average (GCA) standard value uptake ratio (SUVR) based on the brain 18F-florbetapir PET composite cortical SUVR between each ACC-001+QS-21 dose compared with placebo. Secondary endpoints included safety, immunogenicity and pharmacodynamics. Exploratory endpoints included cognitive and functional efficacy, and health outcome measures. RESULTS: Of 126 randomized patients (placebo: 40; ACC-001 3 µg+QS-21: 43; and ACC-001 10 µg+QS-21: 43), 125 received study treatment; 92 (73%) completed the study. Change in 18F-florbetapir PET GCA SUVR, was not significantly different between either of the two ACC-001+QS-21 treatment groups and placebo (3 µg +QS-21 vs. placebo diff=-0.03, p=0.54; 10 µg +QS-21 vs. placebo diff=-0.08, p=0.07), but the trend was numerically consistent with a dose response. The geometric mean peak anti-Aß IgG titers were slightly higher in the 10 µg than the 3 µg group. The proportion of responders was similar in both dose groups of ACC-001+QS-21. The cerebrospinal fluid (CSF) p-tau changes from baseline in both active treatment groups were not statistically different from placebo, but were numerically consistent with a dose response (3 µg +QS-21 vs. placebo diff=-3.2, p=0.57; 10 µg +QS-21 vs. placebo diff=-7.0, p=0.19). The vMRI showed statistically significant faster treatment-related decrease in brain volume in the 10 µg group but was not significant in the 3 µg group, compared with placebo (3 µg diff =-1.3 mL/year, p=0.50; 10 µg diff=-4.2 mL/year, p=0.02). Measured plasma Aß levels increased in parallel with peak anti-Aß titers after each injection. Amyloid-related imaging abnormalities with edema/effusion (ARIA-E) were more frequent in patients who received ACC-001+QS-21 than placebo (6% vs. 0%) but none were symptomatic. The most common treatment-emergent adverse events in the active groups were injection reactions, and occurred more frequently in the ACC-001+QS-21 groups than the placebo (48% vs 8%), the majority of which were mild and transient. CONCLUSIONS: Primary biomarker efficacy endpoints were not statistically significant in either dose group. The numerical decreases in 18F-florbetapir PET GCA SUVR suggests a dose-related trend for greater reductions in fibrillar amyloid burden in the ACC-001+QS-21 10 µg group compared with placebo. Likewise, while not significant, there was a numerical trend of decreased CSF p-tau levels with ACC-001, possibly consistent with a downstream effect in the ACC-001+QS-21 group. Insufficient antibody titers or quality, insufficient power to detect a difference, or too short duration of follow up may be reasons why a statistically significant response was not observed. Brain volume measures showed faster volume loss in the 10 µg treatment group, similar to the effect seen in few earlier AD immunotherapy trials which may suggest removal of amyloid and resultant decrease in inflammation. No new, unexpected safety signals were detected.

Increased number of Purkinje cell dendritic swellings in essential tremor.

BACKGROUND AND PURPOSE: Essential Tremor (ET) is among the most prevalent neurologic disorders. Growing clinical and neuro-imaging evidence implicates cerebellar dysfunction in the pathogenesis of ET and emerging postmortem studies have identified structural changes in the cerebellum, particularly in Purkinje cells. In this study we systematically quantified focal Purkinje cell dendritic swellings (DS) in 20 ET vs. 19 control brains. METHODS: In each brain, a standard parasagittal neocerebellar tissue block was harvested. DS were quantified in one 7-µm thick section stained with Luxol Fast Blue/Hematoxylin and Eosin (LH&E) and one section stained with Bielschowsky method. RESULTS: The number of DS were higher in cases than controls by LH&E (1.50 ± 1.79 vs. 0.05 ± 0.23, P = 0.002) and Bielschowsky methods (2.70 ± 3.10 vs. 0.37 ± 0.50, P = 0.002). The number of DS was correlated with the number of torpedoes and marginally inversely correlated with the number of Purkinje cells. CONCLUSION: The current study documents and quantifies an additional structural abnormality in the ET cerebellum, adding to the growing list of such changes in this disease. The mechanisms that underlie this and other structural changes observed in ET are currently unknown, and they deserve additional exploration.

A phase 2 multiple ascending dose trial of bapineuzumab in mild to moderate Alzheimer disease.

BACKGROUND: Bapineuzumab, a humanized anti-amyloid-beta (Abeta) monoclonal antibody for the potential treatment of Alzheimer disease (AD), was evaluated in a multiple ascending dose, safety, and efficacy study in mild to moderate AD. METHODS: The study enrolled 234 patients, randomly assigned to IV bapineuzumab or placebo in 4 dose cohorts (0.15, 0.5, 1.0, or 2.0 mg/kg). Patients received 6 infusions, 13 weeks apart, with final assessments at week 78. The prespecified primary efficacy analysis in the modified intent-to-treat population assumed linear decline and compared treatment differences within dose cohorts on the Alzheimer's Disease Assessment Scale-Cognitive and Disability Assessment for Dementia. Exploratory analyses combined dose cohorts and did not assume a specific pattern of decline. RESULTS: No significant differences were found in the primary efficacy analysis. Exploratory analyses showed potential treatment differences (p < 0.05, unadjusted for multiple comparisons) on cognitive and functional endpoints in study "completers" and APOE epsilon4 noncarriers. Reversible vasogenic edema, detected on brain MRI in 12/124 (9.7%) bapineuzumab-treated patients, was more frequent in higher dose groups and APOE epsilon4 carriers. Six vasogenic edema patients were asymptomatic; 6 experienced transient symptoms. CONCLUSIONS: Primary efficacy outcomes in this phase 2 trial were not significant. Potential treatment differences in the exploratory analyses support further investigation of bapineuzumab in phase 3 with special attention to APOE epsilon4 carrier status. CLASSIFICATION OF EVIDENCE: Due to varying doses and a lack of statistical precision, this Class II ascending dose trial provides insufficient evidence to support or refute a benefit of bapineuzumab.

Hippocampal and entorhinal atrophy in mild cognitive impairment: prediction of Alzheimer disease.

OBJECTIVE: To evaluate the utility of MRI hippocampal and entorhinal cortex atrophy in predicting conversion from mild cognitive impairment (MCI) to Alzheimer disease (AD). METHODS: Baseline brain MRI was performed in 139 patients with MCI, broadly defined, and 63 healthy controls followed for an average of 5 years (range 1 to 9 years). RESULTS: Hippocampal and entorhinal cortex volumes were each largest in controls, intermediate in MCI nonconverters, and smallest in MCI converters to AD (37 of 139 patients converted to AD). In separate Cox proportional hazards models, covarying for intracranial volume, smaller hippocampal volume (risk ratio [RR] 3.62, 95% CI 1.93 to 6.80, p < 0.0001), and entorhinal cortex volume (RR 2.43, 95% CI 1.56 to 3.79, p < 0.0001) each predicted time to conversion to AD. Similar results were obtained for hippocampal and entorhinal cortex volume in patients with MCI with Mini-Mental State Examination (MMSE) scores > or = 27 out of 30 (21% converted to AD) and in the subset of patients with amnestic MCI (35% converted to AD). In the total patient sample, when both hippocampal and entorhinal volume were entered into an age-stratified Cox model with sex, MMSE, education, and intracranial volume, smaller hippocampal volume (RR 2.21, 95% CI 1.14 to 4.29, p < 0.02) and entorhinal cortex volume (RR 2.48, 95% CI 1.54 to 3.97, p < 0.0002) predicted time to conversion to AD. Similar results were obtained in a Cox model that also included Selective Reminding Test (SRT) delayed recall and Wechsler Adult Intelligence Scale-Revised (WAIS-R) Digit Symbol as predictors. Based on logistic regression models in the 3-year follow-up sample, for a fixed specificity of 80%, the sensitivities for MCI conversion to AD were as follows: age 43.3%, MMSE 43.3%, age + MMSE 63.7%, age + MMSE + SRT delayed recall + WAIS-R Digit Symbol 80.6% (79.6% correctly classified), hippocampus + entorhinal cortex 66.7%, age + MMSE + hippocampus + entorhinal cortex 76.7% (85% correctly classified), age + MMSE + SRT delayed recall + WAIS-R Digit Symbol + hippocampus + entorhinal cortex 83.3% (86.8% correctly classified). CONCLUSIONS: Smaller hippocampal and entorhinal cortex volumes each contribute to the prediction of conversion to Alzheimer disease. Age and cognitive variables also contribute to prediction, and the added value of hippocampal and entorhinal cortex volumes is small. Nonetheless, combining these MRI volumes with age and cognitive measures leads to high levels of predictive accuracy that may have potential clinical application.

Neuropathologic findings in essential tremor.

Pathologic findings, including cerebellar changes and brainstem Lewy bodies, distinguished 10 essential tremor (ET) cases from 12 controls. Numbers of torpedoes (p = 0.009) and Bergmann glia (p = 0.046) were increased in cases. Six cases (60%) had Lewy bodies vs 2 controls (16.7%) (odds ratio 7.5, 95% CI 1.04 to 54.1; p = 0.035). Four of these six had an atypical distribution of brainstem Lewy bodies. ET may be pathologically heterogeneous.

Aggregation of vascular risk factors and risk of incident Alzheimer disease.

BACKGROUND: The prevalence of Alzheimer disease (AD) is increasing in the elderly, and vascular risk factors may increase its risk. OBJECTIVE: To explore the association of the aggregation of vascular risk factors with AD. METHODS: The authors followed 1,138 individuals without dementia at baseline (mean age 76.2) for a mean of 5.5 years. The presence of vascular risk factors was related to incident possible and probable AD. RESULTS: Four risk factors (diabetes, hypertension, heart disease, and current smoking) were associated with a higher risk of AD (p < 0.10) when analyzed individually. The risk of AD increased with the number of risk factors (diabetes + hypertension + heart disease + current smoking). The adjusted hazards ratio of probable AD for the presence of three or more risk factors was 3.4 (95% CI: 1.8, 6.3; p for trend < 0.0001) compared with no risk factors. Diabetes and current smoking were the strongest risk factors in isolation or in clusters, but hypertension and heart disease were also related to a higher risk of AD when clustered with diabetes, smoking, or each other. CONCLUSIONS: The risk of Alzheimer disease (AD) increased with the number of vascular risk factors. Diabetes and current smoking were the strongest risk factors, but clusters including hypertension and heart disease also increased the risk of AD. These associations are unlikely to be explained by misclassification of the outcome, given strong associations when only probable AD is considered.

Motor signs during the course of Alzheimer disease.

BACKGROUND: Motor signs (MOSIs) are common in Alzheimer disease (AD) and may be associated with rates of cognitive decline, mortality, and cost of care. OBJECTIVE: To describe the progression and identify predictors of individual MOSIs in AD. METHODS: A cohort of 474 patients with AD at early stages was followed semiannually for up to 13.1 years (mean 3.6 years) in five centers in Europe and the United States. MOSIs were rated using a standardized portion of the Unified Parkinson's Disease Rating Scale. Overall, 3,030 visits/assessments of MOSIs (average 6.4/patient) were performed. Prevalence and incidence rates were calculated, and cumulative risk graphs were plotted for individual non-drug-induced MOSI domains. Rates of change over time taking into account potential covariates were also estimated. With use of each MOSI domain as outcome in Cox models, predictors of MOSI incidence were identified. RESULTS: At least one MOSI was detected in 13% of patients at first examination and in 36% for the last evaluation. Total MOSI score increased at an annual rate of 3% of total possible score. Rates of annual change for speech/facial expression (4%), rigidity (2.45%), posture/gait (3.9%), and bradykinesia (3.75%) were of similar magnitude, and their occurrence increased from first (3 to 6%) to last (22 to 29%) evaluation. Tremor was less frequent throughout the course of the disease (4% at first and 7% at last evaluation) and worsened less (0.75% increase/year). CONCLUSIONS: Most motor signs occur frequently and progress rapidly in Alzheimer disease. Tremor is an exception in that it occurs less frequently and advances at slower rates.

Plasma A[beta]40 and A[beta]42 and Alzheimer's disease: relation to age, mortality, and risk.

BACKGROUND: Plasma amyloid [beta]-peptide (A[beta]) 40 and A[beta]42 levels are increased in persons with mutations causing early-onset familial Alzheimer's disease (AD). Plasma A[beta]42 levels were also used to link microsatellite genetic markers to a putative AD genetic locus on chromosome 10 and were observed in patients with incipient sporadic AD. METHODS: The authors measured plasma A[beta]40 and A[beta]42 levels using a sandwich ELISA after the initial examination of 530 individuals participating in an epidemiologic study of aging and dementia. Participants were examined at 18-month intervals, and plasma A[beta]40 and A[beta]42 levels were repeated in 307 subjects 3 years after baseline. RESULTS: Compared with individuals who never developed AD, patients with AD at baseline and those who developed AD during the follow-up had significantly higher A[beta]42, but not A[beta]40, plasma levels. The risk of AD in the highest quartile of plasma A[beta]42 was increased by more than twofold over that in the lowest quartile. The highest plasma A[beta]42 levels were observed in patients with AD who died during the follow-up. Plasma A[beta]42, but not A[beta]40, levels decreased over time in patients with newly acquired AD. CONCLUSIONS: Plasma A[beta]40 and A[beta]42 increase with age and are strongly correlated with each other. Plasma A[beta]40 and A[beta]42 levels are elevated in some patients before and during the early stages of AD but decline thereafter. High plasma A[beta]42 levels may also be associated with mortality in patients with AD.

Natural history of Alzheimer's disease.

Alzheimer's disease (AD) is the principal cause of dementia in the elderly, and affects about 15 million people worldwide. The earliest symptom is usually an insidious impairment of memory. As the disease progresses, there is increasing impairment of language and other cognitive functions. Problems occur with naming and word-finding, and later with verbal and written comprehension and expression. Visuospatial, analytic and abstract reasoning abilities, judgment, and insight become affected. Behavioral changes may include delusions, hallucinations, irritability, agitation, verbal or physical aggression, wandering, and disinhibition. Ultimately, there is loss of self-hygiene, eating, dressing, and ambulatory abilities, and incontinence and motor dysfunction. Before diagnosis of AD, individuals may have memory complaints, which represent a period of mild cognitive impairment (MCI). Before MCI, there is a prodromal, ill-defined presymptomatic period of disease ('pre-MCI"). In this review, we particularly focus on these earliest stages. We also discuss the more advanced stages of AD, and address factors that may influence disease course. Understanding the natural history of AD will allow better targeting of the disease-modifying treatments that are on the horizon.

Characterization of initiated cells in N-methylnitrosourea-induced carcinogenesis of the CNS in the adult rat.

Glial tumors may originate from the malignant transformation of multipotent glial progenitor cells, but tools to study malignant transformation leading to gliomas are limited by the lack of biological systems that represent early stages of this disease in adult animals. In order to characterize the initiated cells that give rise to gliomas, we have employed the N-methylnitrosourea (MNU) model for induction of brain tumors in adult rats (Rushing et al., 1998). Specifically, we have isolated and cultured transformed (premalignant) cells from normal-appearing brains of rats exposed to MNU for 10 weeks and from histologically abnormal brains of rats exposed to MNU for 15 weeks. We compared them with cells cultured from control animals under identical conditions. Cultured cells were classified according to their morphology, immunophenotype, karyotype, proliferation capacity, and tumorigenicity in athymic mice. Cultures from untreated normal rat brains grew as monolayers and had normal karyotypes (42 X,Y), epithelioid morphology, and slow proliferative capacity (doubling time > 120 h). In contrast, cultured cells from brains of MNU-exposed animals had karyotypes that ranged from normal to highly aneuploid. Aneuploid lines grew rapidly in multilayers (doubling time < 24 h), had differentiated astrocytic or oligodendroglial morphology and immunohistochemical staining profile, and yielded tumors in athymic mice. Initiated cells with minor chromosomal aberrations assumed mixed bipolar or tripolar morphologies in high density cultures, proliferated rapidly, but showed contact inhibition and failed to induce tumors when injected s.c. in athymic mice. In general, lines showing no evidence of chromosomal aberrations had the most epithelioid morphology, proliferated slowly (doubling time > 72 h), and retained strict contact growth inhibition. The presumed undifferentiated glial progenitor cells in culture from either control or MNU-treated rats variably expressed markers such as vimentin, nestin, and NG2 proteoglycan, and they weakly expressed the mature astrocytic or oligodendroglial markers glial fibrillary acidic protein or galactocerbroside, respectively. These cultures differentiated to bipolar-tripolar morphology with concomitant maturation to a GFAP+ or GalC+ phenotype upon exposure to secondary messengers such as dibutyryl-cyclic-AMP and/or growth factors such as basic fibrillary growth factor. Continuous stimulation with these messengers resulted in terminal differentiation and consequent death upon withdrawal of the stimulus. These results provide information that could lead to detailed characterization of initiated, premalignant cells in the adult brain and to a better understanding of glial carcinogenesis.

Alzheimer's disease.

In this case study, we describe the symptoms, neuropsychological testing, and brain pathology of a man with Alzheimer's disease (AD). AD commonly presents with impairment of memory and language function. In this case, language difficulties were noted more prominently than was memory impairment. Throughout the limbic system and neocortex of the patient were large numbers of senile plaques and neurofibrillary tangles, the pathological hallmarks of AD.

Parkinson's disease.

In this case study, we describe the symptoms, neurological examination, test results, and brain pathology of a man with Parkinson's disease (PD). PD commonly presents with tremor or changes in one's ability to walk or move. Other major difficulties caused by this disease include rigidity of the body, slowness of movement, and postural imbalance. The disease symptoms principally result from the degeneration of a specific population of neuronal cells in the brain stem, in a region called the pars compacta of the substantia nigra. Pathology shows the loss of these cells and the appearance of characteristic neuronal cytoplasmic inclusions called Lewy bodies, which are composed principally of aggregated alpha-synuclein protein.

Glutamate transporter EAAT2 splice variants occur not only in ALS, but also in AD and controls.

OBJECTIVE: To ascertain the specificity of alternatively spliced mRNA variants of the astroglial glutamate transporter EAAT2 for ALS. BACKGROUND: An important hypothesis for ALS pathogenesis is that motor neuron injury may result from chronically elevated glutamate levels in the CNS. Supporting this idea are reports of decreased glutamate transport in ALS. This in turn has recently been suggested to be due to the presence of aberrant mRNA splice variants for EAAT2 in ALS. METHODS: Postmortem human brain tissue was obtained from different brain regions of patients with ALS, normal controls (NC), and patients with AD and Lewy body dementia (LB)-neurodegenerative diseases in which motor neurons are unaffected. Brain RNA was analyzed for EAAT2 isoforms using reverse transcription PCR and cDNA cloning/sequencing methods. RESULTS: Splice variants lacking exons 7 or 9 were present in ALS brain, as previously reported, but were also present in brains from NC, AD, and LB patients. PCR product sequence analyses from non-ALS brain show variant splicing identical to that reported for ALS. Quantitative PCR analysis shows that these isoforms may be somewhat more abundant in ALS than AD, LB, and NC brains. CONCLUSIONS: EAAT2 mRNA splice variants are found in the brains of NC and AD patients, as in ALS. The authors cannot exclude the possibility that quantitative changes in variant EAAT2 isoforms might relate directly, or indirectly, to ALS pathology. However, the qualitative presence of these "abnormal" EAAT2 splice variants does not appear to be sufficient to explain motor neuron degeneration in ALS.

Apoptosis and neurologic disease.

Many neurological disorders involve cell death. During development of the nervous system, cell death is a normal feature. Elimination of substantial numbers of initially generated cells enables useful pruning of "mismatched" or excessive cells produced by exuberance during the proliferative and migratory phases of development. Such cell death, occurring by "programmed" pathways, is termed apoptosis. In mature organisms, cells die in two major fashions, either by necrosis or apoptosis. In the adult nervous system, because there is little cell production during adulthood, there is little normal cell death. However, neurological disease is often associated with significant neural cell death. Acute disorders, occurring over minutes to hours, such as brain trauma, infarction, hemorrhage, or infection, prominently involve cell death, much of which is by necrosis. Chronic disorders, with relatively slow central nervous system degeneration, may occur over years or decades, but may involve cell losses. Such disorders include motor neuron diseases such as amyotrophic lateral sclerosis (ALS), cerebral dementing disorders such as Alzheimer's disease and frontotemporal dementia, and a variety of degenerative movement disorders including Parkinson's disease, Huntington's disease, and the inherited ataxias. There is evidence that the mechanism of neuronal cell death in these disorders may involve apoptosis. Direct conclusive evidence of apoptosis is scarce in these chronic disorders, because of the swiftness of cell death in relation to the slowness of the disease. Thus, at any particular time point of assessment, very few cells would be expected to be undergoing death. However, it is clearly of importance to define the type of cell death in these disorders. Of significance is that while treating the underlying causes of these conditions is an admirable goal, it may also be possible to develop productive therapies based on alleviating the process of cell death. This is particularly likely if this cell loss is through apoptosis, a programmed process for which the molecular cascade is increasingly understood. This article reviews our understanding of apoptosis in the nervous system, concentrating on its possible roles in chronic neurodegenerative disorders.