Effects of aerobic exercise on mild cognitive impairment: a controlled trial

OBJECTIVES

To examine the effects of aerobic exercise on cognition and other biomarkers associated with Alzheimer disease pathology for older adults with mild cognitive impairment, and assess the role of sex as a predictor of response.

DESIGN

Six-month, randomized, controlled, clinical trial.

SETTING

Veterans Affairs Puget Sound Health Care System clinical research unit.

PARTICIPANTS

Thirty-three adults (17 women) with amnestic mild cognitive impairment ranging in age from 55 to 85 years (mean age, 70 years). Intervention Participants were randomized either to a high-intensity aerobic exercise or stretching control group. The aerobic group exercised under the supervision of a fitness trainer at 75% to 85% of heart rate reserve for 45 to 60 min/d, 4 d/wk for 6 months. The control group carried out supervised stretching activities according to the same schedule but maintained their heart rate at or below 50% of their heart rate reserve. Before and after the study, glucometabolic and treadmill tests were performed and fat distribution was assessed using dual-energy x-ray absorptiometry. At baseline, month 3, and month 6, blood was collected for assay and cognitive tests were administered.

MAIN OUTCOME MEASURES

Performance measures on Symbol-Digit Modalities, Verbal Fluency, Stroop, Trails B, Task Switching, Story Recall, and List Learning. Fasting plasma levels of insulin, cortisol, brain-derived neurotrophic factor, insulinlike growth factor-I, and beta-amyloids 40 and 42.

RESULTS

Six months of high-intensity aerobic exercise had sex-specific effects on cognition, glucose metabolism, and hypothalamic-pituitary-adrenal axis and trophic activity despite comparable gains in cardiorespiratory fitness and body fat reduction. For women, aerobic exercise improved performance on multiple tests of executive function, increased glucose disposal during the metabolic clamp, and reduced fasting plasma levels of insulin, cortisol, and brain-derived neurotrophic factor. For men, aerobic exercise increased plasma levels of insulinlike growth factor I and had a favorable effect only on Trails B performance.

CONCLUSIONS

This study provides support, using rigorous controlled methodology, for a potent nonpharmacologic intervention that improves executive control processes for older women at high risk of cognitive decline. Moreover, our results suggest that a sex bias in cognitive response may relate to sex-based differences in glucometabolic and hypothalamic-pituitary-adrenal axis responses to aerobic exercise.

Performance characteristics of plasma amyloid-beta 40 and 42 assays

Identifying biomarkers of Alzheimer's disease (AD) risk will be critical to effective AD prevention. Levels of circulating amyloid-beta (Abeta) 40 and 42 may be candidate biomarkers. However, properties of plasma Abeta assays must be established. Using five different protocols, blinded samples were used to assess: intra-assay reproducibility; impact of EDTA vs. heparin anticoagulant tubes; and effect of time-to-blood processing. In addition, percent recovery of known Abeta concentrations in spiked samples was assessed. Median intra-assay coefficients of variation for the assay protocols ranged from 6-24% for Abeta(40), and 8-14% for Abeta(42). There were no systematic differences in reproducibility by collection method. Plasma concentrations of Abeta (particularly Abeta(42) appeared stable in whole blood kept in ice packs and processed as long as 24 hours after collection. Recovery of expected concentrations was modest, ranging from -24% to 44% recovery of Abeta(40), and 17% to 61% of Abeta(42). In conclusion, across five protocols, plasma Abeta(40) and Abeta(42) levels were measured with generally low error, and measurements appeared similar in blood collected in EDTA versus heparin. While these preliminary findings suggest that measuring plasma Abeta(40) and Abeta(42) may be feasible in varied research settings, additional work in this area is necessary.

A worldwide multicentre comparison of assays for cerebrospinal fluid biomarkers in Alzheimer's disease

BACKGROUND

Different cerebrospinal fluid (CSF) amyloid-beta 1-42 (Abeta(1-42)), total Tau (Tau) and Tau phosphorylated at threonine 181 (P-Tau) levels are reported, but currently there is a lack of quality control programmes. The aim of this study was to compare the measurements of these CSF biomarkers, between and within centres.

METHODS

Three CSF-pool samples were distributed to 13 laboratories in 2004 and the same samples were again distributed to 18 laboratories in 2008. In 2004 six laboratories measured Abeta(1-42), Tau and P-Tau and seven laboratories measured one or two of these marker(s) by enzyme-linked immunosorbent assays (ELISAs). In 2008, 12 laboratories measured all three markers, three laboratories measured one or two marker(s) by ELISAs and three laboratories measured the markers by Luminex.

RESULTS

In 2004, the ELISA intercentre coefficients of variance (interCV) were 31%, 21% and 13% for Abeta(1-42), Tau and P-Tau, respectively. These were 37%, 16% and 15%, respectively, in 2008. When we restricted the analysis to the Innotest (N = 13) for Abeta(1-42), lower interCV were calculated (22%). The centres that participated in both years (N = 9) showed interCVs of 21%, 15% and 9% and intra-centre coefficients (intraCV) of variance of 25%,18% and 7% in 2008.

CONCLUSIONS

The highest variability was found for Abeta(1-42). The variabilities for Tau and P-Tau were lower in both years. The centres that participated in both years showed a high intraCV comparable to their interCV, indicating that there is not only a high variation between but also within centres. Besides a uniform standardization of (pre)analytical procedures, the same assay should be used to decrease the inter/intracentre variation.

Relationship between Amyloid β (Aβ) Protein and Inflammatory Markers in Down Syndrome (DS) (98.19)

Brain autopsy data from persons with DS showed that the neuropathology of Alzheimer disease (AD) is always present in DS 40 years of age and older. The core protein of the neuritic plaque is Aβ protein. Studies have suppoted the role of immune abnormalities and inflammation in the pathogenesis of DS. We hypothesized that the levels of TNFα and Cystatin C would be higher in DS than controls, and would correlate with Aβ levels. The study included 40 persons with DS (44±8 years old) and age-matched controls. Plasma levels of Aβ40 and Aβ42 , TNFα and Cystatin C were quantitated by using an ELISA. Aβ40 and Aβ42, TNFα and Cystatin C levels were higher in DS than controls (p<.001). Although there was significant relation between Aβ40 and Aβ42 levels (r=.6; p<.01)in DS, there was no relation between Aβ40 and Aβ42 levels with TNFα or Cystatin C. The higher TNFαand Cystatin C levels indicate a chronic state of immune activation in DS. Because there was no relation between Aβ and TNFα or Cyststin C the data suggests that increases in TNFα and Cystatin C reflect more infections in DS than AD neuropathology.

Plasma amyloid levels and the risk of AD in normal subjects in the Cardiovascular Health Study

OBJECTIVES

To examine the association between incident Alzheimer disease (AD), and plasma A beta 1-40 and A beta 1-42 levels in normal and mild cognitive impairment (MCI) subjects in a subgroup of participants of the Cardiovascular Health Study Cognition Study.

METHODS

We determined the plasma A beta 1-40 and A beta 1-42 levels of 274 nondemented subjects (232 normals and 42 with MCI) in 1998-1999 and repeated the measurements in 2002-2003. The mean age of the subjects at baseline was 79.3 +/- 3.6 years. We examined the association between A beta levels and incident AD over the ensuing 4.5 years, controlling for age, cystatin C level (marker of glomerular function), apolipoprotein E-4 allele, Modified-Mini-Mental State Examination scores, and MRI-identified infarcts.

RESULTS

In an unadjusted prospective model in normal subjects, both A beta 1-40 and A beta 1-42 levels in 1998-1999 were associated with incident AD (n = 55) in 2002-2003 (longitudinal analysis). In the fully adjusted multivariate model, neither A beta 1-42 nor A beta 1-40 nor their ratio was associated with incident AD. However, adjustment had a very small effect on point estimates for A beta 1-42, from an odds ratio (OR) of 1.61 (p = 0.007) in the unadjusted model to an OR of 1.46 (p = 0.08) in the fully adjusted model. In 2002-2003 (cross-sectional analysis), only the unadjusted models showed that both peptides were associated with AD.

CONCLUSIONS

Plasma A beta levels are affected by age and by systemic and CNS vascular risk factors. After controlling for these conditions, A beta-40 and A beta 1-42 are weak predictors of conversion to Alzheimer disease (AD) in normal subjects and are only weakly associated with AD in cross-sectional analysis. Consequently, plasma levels of A beta do not seem to be useful biomarkers for AD.

Hypometabolism and altered cerebrospinal fluid markers in normal apolipoprotein E E4 carriers with subjective memory complaints

BACKGROUND

We examined whether cerebral metabolic rates for glucose (CMRglc) on 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) and cerebrospinal fluid (CSF) markers of Alzheimer's disease (AD) are altered in cognitively normal apolipoprotein E (ApoE) E4 carriers with subjective memory complaints (SMC).

METHODS

Twenty-eight middle-aged normal subjects (NL) were examined, including 13 E4 carriers (E4+; 6 with SMC [SMC+] and 7 without SMC [SMC-]) and 15 noncarriers (E4-; 7 SMC+ and 8 SMC-). Subjects received an FDG-PET scan and a lumbar puncture to measure CSF total (T-Tau) and hyperphosphorylated tau(231) (P-Tau), 40 and 42 amino acid forms of beta-amyloid (Abeta40 and Abeta42), and F(2)-isoprostane (IP).

RESULTS

As compared with E4-, E4+ subjects showed decreased CMRglc in AD-related brain regions and associated higher CSF IP, P-Tau, T-Tau, and P-Tau/Abeta42 levels (p's < .05). As compared with SMC-, SMC+ subjects showed reduced parietotemporal and parahippocampal gyrus (PHG) CMRglc. A significant ApoE by SMC status interaction was found, with the E4+/SMC+ showing the lowest PHG CMRglc and the highest CSF IP, P-Tau, and P-Tau/Abeta42 levels as compared with all other subgroups (p's < or = .05). The combination of CSF and CMRglc measures significantly improved the accuracy of either measures alone in discriminating ApoE groups (86% accuracy, odds ratio [OR] = 4.1, p < .001) and E4+/SMC+ from all other subgroups (86% accuracy, OR = 3.7, p = .005). Parahippocampal gyrus CMRglc was the most accurate discriminator of SMC groups (75% accuracy, OR = 2.4, p < .001).

CONCLUSIONS

Normal E4 carriers with SMC show altered AD-related CSF and FDG-PET measures. Longitudinal studies are needed to assess whether these brain abnormalities foreshadow clinical decline.

Amyloid beta protein as a marker or risk factor of Alzheimer's disease

Alzheimer disease (AD) is a neurodegenerative disease that affects cognition, behavior and function. The etiology of the disease is unknown, however, the Primary Risk Factors for AD are aging, and family history. Neurofibrillary tangles (NFT) and amyloid-bearing neuritic plaques in the limbic and cerebral cortices are the characteristic neuropathologic lesions in brains of patients with AD. The NFT is mainly composed of hyprephosphorylated tau, whereas the major component of the neuritic plaques is the amyloid beta (Abeta) protein. The clinical diagnosis of probable AD is based on history, physical examination, neuropsychological testing, laboratory studies and neuroimaging techniques. However, there is no specific laboratory marker to support the diagnosis of definite AD or monitoring the progression of the disease. Several biochemical markers related to neuropathology have been identified in cerebrospinal fluid (CSF). We describe the studies of CSF or blood levels of amyloid beta protein in patients with AD and age-matched nondemented controls. Due to the heterogeneity and complex nature of the disease, it is highly unlikely that that a single marker specific for AD will be found.

Elevated plasma beta-amyloid peptide Abeta(42) levels, incident dementia, and mortality in Down syndrome

BACKGROUND

Deposition of the beta-amyloid peptide Abeta(42) is thought to be an important initial step in the pathogenesis of Alzheimer disease (AD). Individuals with Down syndrome have increased levels of beta-amyloid peptides and an increased risk for AD.

OBJECTIVE

To examine the relation of plasma levels of Abeta(42) and Abeta(40) to the risk of dementia in nondemented participants and all-cause mortality in adults with Down syndrome.

DESIGN

Prospective, community-based longitudinal cohort study.

SETTING

State and voluntary service providers in New York State.

PARTICIPANTS

Adults with Down syndrome (N = 204).

MAIN OUTCOME MEASURE

Plasma Abeta(42) and Abeta(40) levels were measured at initial examination. Participants were assessed for cognitive and functional abilities, behavioral/psychiatric conditions, and health and vital status at 14- to 18-month intervals for 4 cycles of data collection.

RESULTS

Among participants who were nondemented at baseline, those in the middle and highest tertiles of plasma Abeta(42) levels were more than 2 times as likely to develop AD as those in the lowest tertile. Compared with participants without AD, participants with prevalent AD had higher levels of plasma Abeta(42) but not Abeta(40). Among all participants, those in the highest tertile of plasma Abeta(42) level at baseline were more than twice as likely to die during the study period as those in the lowest tertile, whereas there was no difference in risk of death between those in the middle and lowest tertiles of plasma Abeta(42) level.

CONCLUSION

Elevations in plasma Abeta(42) peptide levels are associated with earlier onset of AD and increased risk of death.

Decreased cerebrospinal fluid amyloid beta (1-40) levels in frontotemporal lobar degeneration

The role of amyloid metabolism in the pathophysiology of frontotemporal lobar degeneration (FTLD) has yet to be elucidated. We compared CSF levels of amyloid beta 1-40 (Abeta40) and amyloid beta 1-42 (Abeta42) in patients with FTLD (n = 21) versus patients with Alzheimer's disease (AD, n = 39) and in control subjects (n = 30). While in AD cases Abeta42 levels were lower and CSF Abeta40 levels equal to those in controls, a significant decrease in Abeta40 and increase in the CSF Abeta42/Abeta40 ratio was observed in FTLD compared with AD and control subjects. These findings favour a differential involvement of amyloid beta peptides in FTLD compared with AD.

Imaging and CSF studies in the preclinical diagnosis of Alzheimer's disease

It is widely believed that the path to early and effective treatment for Alzheimer's disease (AD) requires the development of early diagnostic markers that are both sensitive and specific. To this aim, using longitudinal study designs, we and others have examined magnetic resonance imaging (MRI), 2-fluoro-2-deoxy-d-glucose-positron emission tomography (FDG/PET), and cerebrospinal fluid (CSF) biomarkers in cognitively normal elderly (NL) subjects and in patients with mild cognitive impairment (MCI). Such investigations have led to the often replicated findings that structural evidence of hippocampal atrophy as determined by MRI, as well as metabolic evidence from FDG-PET scan of hippocampal damage, predicts the conversion from MCI to AD. In this article we present a growing body of evidence of even earlier diagnosis. Brain pathology can be detected in NL subjects and used to predict future transition to MCI. This prediction is enabled by examinations revealing reduced glucose metabolism in the hippocampal formation (hippocampus and entorhinal cortex [EC]) as well as by the rate of medial temporal lobe atrophy as determined by MRI. However, neither regional atrophy nor glucose metabolism reductions are specific for AD. These measures provide secondary not primary evidence for AD. Consequently, we will also summarize recent efforts to improve the diagnostic specificity by combining imaging with CSF biomarkers and most recently by evaluating amyloid imaging using PET. We conclude that the combined use of conventional imaging, that is MRI or FDG-PET, with selected CSF biomarkers incrementally contributes to the early and specific diagnosis of AD. Moreover, selected combinations of imaging and CSF biomarkers measures are of importance in monitoring the course of AD and thus relevant to evaluating clinical trials.

Intraneuronal Abeta immunoreactivity is not a predictor of brain amyloidosis-beta or neurofibrillary degeneration

Amyloid beta (Abeta) immunoreactivity in neurons was examined in brains of 32 control subjects, 31 people with Down syndrome, and 36 patients with sporadic Alzheimer's disease to determine if intraneuronal Abeta immunoreactivity is an early manifestation of Alzheimer-type pathology leading to fibrillar plaque formation and/or neurofibrillary degeneration. The appearance of Abeta immunoreactivity in neurons in infants and stable neuron-type specific Abeta immunoreactivity in a majority of brain structures during late childhood, adulthood, and normal aging does not support this hypothesis. The absence or detection of only traces of reaction with antibodies against 4-13 aa and 8-17 aa of Abeta in neurons indicated that intraneuronal Abeta was mainly a product of alpha- and gamma-secretases (Abeta(17-40/42)). The presence of N-terminally truncated Abeta(17-40) and Abeta(17-42) in the control brains was confirmed by Western blotting and the identity of Abeta(17-40) was confirmed by mass spectrometry. The prevalence of products of alpha- and gamma -secretases in neurons and beta- and gamma-secretases in plaques argues against major contribution of Abeta-immunopositive material detected in neuronal soma to amyloid deposit in plaques. The strongest intraneuronal Abeta(17-42) immunoreactivity was observed in structures with low susceptibility to fibrillar Abeta deposition, neurofibrillary degeneration, and neuronal loss compared to areas more vulnerable to Alzheimer-type pathology. These observations indicate that the intraneuronal Abeta immunoreactivity detected in this study is not a predictor of brain amyloidosis or neurofibrillary degeneration. The constant level of Abeta immunoreactivity in structures free from neuronal pathology during essentially the entire life span suggests that intraneuronal amino-terminally truncated Abeta represents a product of normal neuronal metabolism.

Increased Amyloid β Protein Levels in Children with Down Syndrome (129.47)

Objective: To quantitate plasma amyloid β protein (Aβ)40, Aβ42, and neopterin levels in Down Syndrome (DS) children and controls.

Background: DS persons (&gt;40 years) have neuropathological changes characteristic of Alzheimer disease (AD). Soluble forms of Aβ generated from amyloid precursor protein (APP) end at C-terminal residues 40 and 42. Neopterin is an immune activation marker for the cell-mediated immune response.

Design/Methods: Blood was collected from DS (N = 35; 7 ± 3.8 years old) and their siblings (N = 34; 10 ± 4.5). Plasma Aβ40, Aβ42, and neopterin levels were quantitated by ELISA.

Results: Aβ40 (Mean ± SD; 277 ± 70 pg/ml) and Aβ42 (31 ± 8 pg/ml) levels were higher in DS children than controls (Aβ40 155 ± 35 pg/ml, Aβ42 22 ± 5 pg/ml) (p&lt;.0001). There were significant negative correlations between age and Aβ40 in DS (r=.47, p&lt;.004) or controls (r=.38, p&lt;.026) and Aβ42 levels in DS (r=.61, p&lt;.001) but not in controls. Neopterin levels were higher in DS (3.01 ± 1.37 ng/ml) than controls (1.57 ± 0.65 ng/ml) (p&lt;.0001). There was no correlation between neopterin levels and age, and Aβ40 or Aβ42 levels in DS or controls.

Conclusion: The overexpression of APP gene in DS leads to increases in plasma Aβ40 and Aβ42 levels before plaque formation in DS brain. A lack of correlation between neopterin and Aβ levels suggests that higher neopterin concentrations in DS reflect inflammatory cell activation rather than AD neuropathology.

Humoral immune responses to peptides derived from the beta-amyloid peptide C-terminal sequence

There is a continuing interest in the immunochemical quantification of isoforms of amyloid beta-peptide (Abeta) in body fluids of patients with Alzheimer's disease (AD); however, at present there is no general procedure to produce and test the required antibodies. We examined various methods to generate rabbit anti-Abeta; antibodies that are specific for Abeta(38), Abeta(40) and Abeta(42), and we tested their specificity and sensitivity by ELISA and Western blotting. To produce high-affinity antibodies required repeated inoculations of small doses of peptide conjugates over a period of at least 6 months. Antibodies generated to peptides derived from the Abeta(42) sequence showed some cross-reactivity with Abeta(40), but antibodies generated to Abeta4 peptides did not cross-react with Abeta(42). The shortest peptide capable of generating antibodies of moderate affinity possessed the sequence Met(35)-Ala(42); however, antibodies raised to the peptide Gly(33)-Ala(42) possessed the greatest affinity (K(D) = 1 nM) and specificity for Abeta(42). The latter antibodies were over 50,000-fold more reactive with Abeta(42) than with Abeta(40). They can detect Abeta isoforms in extracts of normal brain, where the peptides are present at levels below one part per billion. Our results provide methods to generate and characterize the specificity and affinity of anti-Abeta antibodies. This information is necessary to develop sensitive and specific immunoassays to quantify Abeta isoforms in brain extracts and in body fluids.

Increased amyloid beta protein levels in children and adolescents with Down syndrome

BACKGROUND

Persons with Down syndrome (DS) (40 years and older) have neuropathological changes characteristic of Alzheimer disease (AD). Soluble forms of amyloid beta (Abeta) peptide generated from amyloid precursor protein (APP) end at C-terminal residues 40 and 42. The presence of the apolipoprotein E (ApoE) epsilon4 allele is a significant risk factor for the development of sporadic AD. Although preliminary studies have shown an association of plasma Abeta42 and ApoE epsilon4 allele in older persons with DS who have dementia, the relationship between plasma Abeta40 and Abeta42 levels and ApoE phenotypes in children with DS has not been examined. Inflammation might play a role in the growth of DS brains. Neopterin is an immune activation marker for the cell-mediated immune response.

OBJECTIVE

To examine the levels of plasma Abeta40, Abeta42, and neopterin in children or adolescents with DS or controls.

MATERIALS AND METHODS

Blood was collected from DS (N=35; 7+/-3.8 years old) and their siblings (N=34; 10+/-4.5). Plasma Abeta40 and Abeta42, and neopterin levels were quantitated by sandwich ELISA.

RESULTS

Abeta40 and Abeta42 levels were higher in DS than controls. The ratio of Abeta42/Abeta40 was lower in DS than in controls. There were significant negative correlations between age and Abeta40 in DS and controls, and between age and Abeta42 levels in DS but not in controls. There was no association of Abeta40 or Abeta42 levels with Apo E in either group. Neopterin levels were higher in DS than controls, and the levels were not correlated with Abeta40 and Abeta42 levels in DS or controls.

CONCLUSIONS

The over expression of APP gene in DS leads to increases in plasma Abeta40 and Abeta42 levels before plaque formation in DS brain. Higher neopterin concentrations in DS reflect inflammatory cell activation. Further studies are needed to determine whether DS children with lower plasma Abeta42/Abeta40 ratios are at increased risk of developing AD during aging than those with higher ratios.

Cerebral beta-amyloid angiopathy in aged squirrel monkeys

Cerebral beta-amyloid angiopathy (CAA) is an age-related disorder of the brain vasculature that is involved in up to 20% of non-traumatic cerebral hemorrhage in humans. CAA is a risk factor for cognitive decline, and may exacerbate the dementia of Alzheimer's disease. Progress in discovering the cause and potential therapies for this disorder has been hindered by the paucity of animal models, particularly models of idiopathic CAA. The squirrel monkey (Saimiri spp) develops significant CAA in the natural course of aging. To evaluate the suitability of Saimiri as a model of human CAA, we studied the distribution and composition of Abeta subtypes in CAA and parenchymal (senile plaque) deposits in the brains of aged squirrel monkeys, as well as the relationship between vascular beta-amyloid deposition and comorbid vasculopathies that occur in aged humans. Our findings show that: 1) CAA consists ultrastructurally of classical amyloid fibrils and is the principal type of cerebral beta-amyloidosis in squirrel monkeys; 2) The two primary isoforms of Abeta (Abeta40 and Abeta42) coexist in most microvascular and parenchymal lesions of Saimiri, although Abeta40 tends to predominate in larger arterioles; 3) CAA and parenchymal plaques overlap to a considerable degree in most affected brain areas, and are distributed symmetrically in the two hemispheres; 4) Both CAA and plaques are particularly abundant in rostral regions and comparatively sparse in the occipital lobe; 5) Capillaries are especially vulnerable to CAA in squirrel monkeys; and 6) When CAA is severe, it is associated with a small, but significant, increase in other vasculopathies, including microhemorrhage, fibrinoid extravasation and focal gliosis. These findings, in the context of genetic, vascular and immunologic similarities between squirrel monkeys and humans, support the squirrel monkey as a biologically advantageous model for studying the basic biology of idiopathic, age-related CAA, and for testing emerging therapies for human beta-amyloidoses such as Alzheimer's disease.

Blocking the apolipoprotein E/amyloid-beta interaction as a potential therapeutic approach for Alzheimer's disease

The amyloid-beta (Abeta) cascade hypothesis of Alzheimer's disease (AD) maintains that accumulation of Abeta peptide constitutes a critical event in the early disease pathogenesis. The direct binding between Abeta and apolipoprotein E (apoE) is an important factor implicated in both Abeta clearance and its deposition in the brain's parenchyma and the walls of meningoencephalic vessels as cerebral amyloid angiopathy. With the aim of testing the effect of blocking the apoE/Abeta interaction in vivo as a potential novel therapeutic target for AD pharmacotherapy, we have developed Abeta12-28P, which is a blood-brain-barrier-permeable nontoxic, and nonfibrillogenic synthetic peptide homologous to the apoE binding site on the full-length Abeta. Abeta12-28P binds with high affinity to apoE, preventing its binding to Abeta, but has no direct effect on Abeta aggregation. Abeta12-28P shows a strong pharmacological effect in vivo. Its systemic administration resulted in a significant reduction of Abeta plaques and cerebral amyloid angiopathy burden and a reduction of the total brain level of Abeta in two AD transgenic mice models. The treatment did not affect the levels of soluble Abeta fraction or Abeta oligomers, indicating that inhibition of the apoE/Abeta interaction in vivo has a net effect of increasing Abeta clearance over deposition and at the same time does not create conditions favoring formation of toxic oligomers. Furthermore, behavioral studies demonstrated that treatment with Abeta12-28P prevents a memory deficit in transgenic animals. These findings provide evidence of another therapeutic approach for AD.

Neurochemical aftermath of amateur boxing

BACKGROUND

Little solid information is available on the possible risks for neuronal injury in amateur boxing.

OBJECTIVE

To determine whether amateur boxing and severity of hits are associated with elevated levels of biochemical markers for neuronal injury in cerebrospinal fluid.

DESIGN

Longitudinal study.

SETTING

Referral center specializing in evaluation of neurodegenerative disorders.

PARTICIPANTS

Fourteen amateur boxers (11 men and 3 women) and 10 healthy male nonathletic control subjects.

INTERVENTIONS

The boxers underwent lumbar puncture 7 to 10 days and 3 months after a bout. The control subjects underwent LP once.

MAIN OUTCOME MEASURES

Neurofilament light protein, total tau, glial fibrillary acidic protein, phosphorylated tau, and beta-amyloid protein 1-40 (Abeta([1-40])) and 1-42 (Abeta([1-42])) concentrations in cerebrospinal fluid were measured.

RESULTS

Increased levels after a bout compared with after 3 months of rest from boxing were found for 2 markers for neuronal and axonal injury, neurofilament light protein (mean +/- SD, 845 +/- 1140 ng/L vs 208 +/- 108 ng/L; P = .008) and total tau (mean +/- SD, 449 +/- 176 ng/L vs 306 +/- 78 ng/L; P = .006), and for the astroglial injury marker glial fibrillary acidic protein (mean +/- SD, 541 +/- 199 ng/L vs 405 +/- 138 ng/L; P = .003). The increase was significantly higher among boxers who had received many hits (>15) or high-impact hits to the head compared with boxers who reported few hits. In the boxers, concentrations of neurofilament light protein and glial fibrillary acidic protein, but not total tau, were significantly elevated after a bout compared with the nonathletic control subjects. With the exception of neurofilament light protein, there were no significant differences between boxers after 3 months of rest from boxing and the nonathletic control subjects.

CONCLUSIONS

Amateur boxing is associated with acute neuronal and astroglial injury. If verified in longitudinal studies with extensive follow-up regarding the clinical outcome, analyses of cerebrospinal fluid may provide a scientific basis for medical counseling of athletes after boxing or head injury.

Increased cerebrospinal fluid A beta38/A beta42 ratio in Alzheimer disease

We quantitated amyloid beta peptide (A beta) 38, A beta40 and A beta42 levels in matched CSF and plasma from Alzheimer disease (AD) patients and controls. CSF A beta38 and A beta40 levels were similar in AD patients and in controls; however, they were higher in controls with APOE upsilon4 allele than those without. CSF A beta42 levels were lower in AD patients than in controls. The CSF A beta38/42 ratio was higher in AD patients than controls, consistent with the previously reported higher A beta40/42 ratio. A beta38, A beta40 and A beta42 levels in plasma were similar in AD patients and in controls and showed no relationship to levels in CSF. Our findings suggest that the increased CSF A beta38/42 ratio found in AD patients is derived entirely from reduction of CSF A beta42 levels.