Natural history of Alzheimer's disease

Intervention for a Digital, Cognitive, Multi-Domain Alzheimer Risk Velocity Study: Protocol for a Randomized Controlled Trial

Background

In the United States, more than 6 million adults live with Alzheimer disease (AD) that affects 1 out of every 3 older adults. Although there is no cure for AD currently, lifestyle-based interventions aimed at slowing the rate of cognitive decline or delaying the onset of AD have shown promising results. However, most studies primarily focus on older adults (>55 years) and use in-person interventions.

Objective

The aim of this study is to determine the effects of a 2-year digital lifestyle intervention on AD risk among at-risk middle-aged and older adults (45-75 years) compared with a health education control.

Methods

The lifestyle intervention consists of a digitally delivered, personalized health coaching program that directly targets the modifiable risk factors for AD. The primary outcome measure is AD risk as determined by the Australian National University-Alzheimer Disease Risk Index; secondary outcome measures are functional fitness, blood biomarkers (inflammation, glucose, cholesterol, and triglycerides), and cognitive function (Repeatable Battery for the Assessment of Neuropsychological Status and Neurotrack Cognitive Battery). Screening commenced in January 2021 and was completed in June 2021.

Results

Baseline characteristics indicate no difference between the intervention and control groups for AD risk (mean −1.68, SD 7.31; P=.90).

Conclusions

The intervention in the Digital, Cognitive, Multi-domain Alzheimer Risk Velocity is uniquely designed to reduce the risk of AD through a web-based health coaching experience that addresses the modifiable lifestyle-based risk factors.

Trial Registration

ClinicalTrials.gov NCT04559789; https://clinicaltrials.gov/show/NCT04559789

International Registered Report Identifier (IRRID)

DERR1-10.2196/31841

Discovery of [11C]MK-6884: A Positron Emission Tomography (PET) Imaging Agent for the Study of M4Muscarinic Receptor Positive Allosteric Modulators (PAMs) in Neurodegenerative Diseases

The measurement of receptor occupancy (RO) using positron emission tomography (PET) has been instrumental in guiding discovery and development of CNS directed therapeutics. We and others have investigated muscarinic acetylcholine receptor 4 (M4) positive allosteric modulators (PAMs) for the treatment of symptoms associated with neuropsychiatric disorders. In this article, we describe the synthesis, in vitro, and in vivo characterization of a series of central pyridine-related M4 PAMs that can be conveniently radiolabeled with carbon-11 as PET tracers for the in vivo imaging of an allosteric binding site of the M4 receptor. We first demonstrated its feasibility by mapping the receptor distribution in mouse brain and confirming that a lead molecule 1 binds selectively to the receptor only in the presence of the orthosteric agonist carbachol. Through a competitive binding affinity assay and a number of physiochemical properties filters, several related compounds were identified as candidates for in vivo evaluation. These candidates were then radiolabeled with ¹¹C and studied in vivo in rhesus monkeys. This research eventually led to the discovery of the clinical radiotracer candidate [¹¹C]MK-6884.

De Deyn P, C. van Swieten J, M. van Duijn C, van der Zee J, Sleegers K, Van Broeckhoven C. Loss of DPP6 in neurodegenerative dementia: a genetic player in the dysfunction of neuronal excitability

Emerging evidence suggested a converging mechanism in neurodegenerative brain diseases (NBD) involving early neuronal network dysfunctions and alterations in the homeostasis of neuronal firing as culprits of neurodegeneration. In this study, we used paired-end short-read and direct long-read whole genome sequencing to investigate an unresolved autosomal dominant dementia family significantly linked to 7q36. We identified and validated a chromosomal inversion of ca. 4 Mb, segregating on the disease haplotype and disrupting the coding sequence of dipeptidyl-peptidase 6 gene (DPP6). DPP6 resequencing identified significantly more rare variants-nonsense, frameshift, and missense-in early-onset Alzheimer's disease (EOAD, p value = 0.03, OR = 2.21 95% CI 1.05-4.82) and frontotemporal dementia (FTD, p = 0.006, OR = 2.59, 95% CI 1.28-5.49) patient cohorts. DPP6 is a type II transmembrane protein with a highly structured extracellular domain and is mainly expressed in brain, where it binds to the potassium channel Kv4.2 enhancing its expression, regulating its gating properties and controlling the dendritic excitability of hippocampal neurons. Using in vitro modeling, we showed that the missense variants found in patients destabilize DPP6 and reduce its membrane expression (p < 0.001 and p < 0.0001) leading to a loss of protein. Reduced DPP6 and/or Kv4.2 expression was also detected in brain tissue of missense variant carriers. Loss of DPP6 is known to cause neuronal hyperexcitability and behavioral alterations in Dpp6-KO mice. Taken together, the results of our genomic, genetic, expression and modeling analyses, provided direct evidence supporting the involvement of DPP6 loss in dementia. We propose that loss of function variants have a higher penetrance and disease impact, whereas the missense variants have a variable risk contribution to disease that can vary from high to low penetrance. Our findings of DPP6, as novel gene in dementia, strengthen the involvement of neuronal hyperexcitability and alteration in the homeostasis of neuronal firing as a disease mechanism to further investigate.

A novel once-daily fixed-dose combination of memantine extended release and donepezil for the treatment of moderate to severe Alzheimer's disease: two phase I studies in healthy volunteers

BACKGROUND

Combining two standard-of-care medications for Alzheimer's disease (AD) into a single once-daily dosage unit may improve treatment adherence, facilitate drug administration, and reduce caregiver burden. A new fixed-dose combination (FDC) capsule containing 28 mg memantine extended release (ER) and 10 mg donepezil was evaluated for bioequivalence with co-administered commercially available memantine ER and donepezil, and for bioavailability with regard to food intake.

METHODS

Two phase I, single-dose, randomized, open-label, crossover studies were conducted in 18- to 45-year-old healthy individuals. In MDX-PK-104 study, fasting participants (N = 38) received co-administered memantine ER and donepezil or the FDC. In MDX-PK-105 study, participants (N = 36) received three treatments: intact FDC taken while fasting or after a high-fat meal, or FDC contents sprinkled on applesauce while fasting. Standard pharmacokinetic parameters for memantine and donepezil were calculated from the plasma concentration time-curve using non-compartmental analyses. Linear mixed-effects models were used to compare: (a) FDC versus co-administered individual drugs; (b) FDC fasted versus with food; and (c) FDC sprinkled on applesauce versus FDC intact, both fasted. Safety parameters were also evaluated.

RESULTS

The FDC capsule was bioequivalent to co-administered memantine ER and donepezil. There was no significant food effect on the bioavailability of the FDC components. There were no clinically relevant differences in time to maximum plasma concentration or safety profiles across treatments.

CONCLUSIONS

An FDC capsule containing 28 mg memantine ER and 10 mg donepezil is bioequivalent to commercially available memantine ER and donepezil, and bioavailability is not affected by food intake or sprinkling of capsule contents on applesauce.

Cumulative, additive benefits of memantine-donepezil combination over component monotherapies in moderate to severe Alzheimer's dementia: a pooled area under the curve analysis

INTRODUCTION

Treatment in moderate or severe Alzheimer's disease (AD) often involves adding memantine to a cholinesterase-inhibitor (ChEI: donepezil, galantamine, rivastigmine). Evidence from six-month randomized trials and long-term observational studies supports superiority of memantine-ChEI combination to ChEI monotherapy. We utilized area-under-the-curve (AUC) analysis to assess six-month cumulative treatment efficacy of memantine-donepezil combination versus component monotherapies on individual clinical domains and on a composite index.

METHODS

Data were pooled from 1,408 individuals with moderate to severe AD from four six-month randomized trials of memantine monotherapy (n = 570) or add-on therapy (donepezil-only subset: n = 847). AUC changes from baseline on measures of cognition (SIB), function (ADCS-ADL19), behavior (NPI), global status (CIBIC-Plus), and a composite index (4D-CI: equally weighted composite of four domain measures) were calculated using the trapezoidal rule and evaluated via analysis of covariance (ANCOVA) (2-sided-α = 0.05). AUC results were contrasted with visit-by-visit changes from baseline ("snapshot analysis"), performed using a mixed-effects model with repeated measures (MMRM).

RESULTS

Over the entire six-month period, placebo-only treatment was associated with significant cumulative worsening on all outcomes. Memantine-donepezil combination showed significantly greater AUC improvements (point x week) on the SIB, NPI, and CIBIC-Plus than placebo-donepezil (SIB: 68.4 versus 32.0, P = 0.019; NPI: -74.3 versus -28.2, P = 0.003; CIBIC-Plus: -2.5 versus 1.4, P = 0.006) and memantine-only monotherapies (SIB: 68.4 versus 12.0, P <0.001; NPI: -74.3 versus -7.4, P <0.001; CIBIC-Plus: -2.5 versus 2.7, P <0.001), whereas these comparisons were not significant for the ADCS-ADL19 (memantine-donepezil (1.4) versus placebo-donepezil (-0.9), P = 0.407; versus memantine-only (-12.2), P = 0.310). Composite index analysis demonstrated significant cumulative advantages of memantine-donepezil combination (630.0) over placebo-donepezil (344.7, P <0.001) and memantine-only (152.1, P <0.001) treatments. Combining memantine and donepezil had an additive effect. Compared with AUC analysis, baseline-to-endpoint change-score analysis underestimated effects of combination therapy, monotherapies, or both.

CONCLUSIONS

This large pooled area-under-the-curve analysis of randomized-trial data in moderate to severe AD provides ecologically valid support that adding memantine to stable donepezil results in overall clinical benefits that are additive compared with individual monotherapies, continue to accumulate through six-month treatment, and are at least 50% greater than those of monotherapies.

A review of β-amyloid neuroimaging in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia worldwide. As advancing age is the greatest risk factor for developing AD, the number of those afflicted is expected to increase markedly with the aging of the world's population. The inability to definitively diagnose AD until autopsy remains an impediment to establishing effective targeted treatments. Neuroimaging has enabled in vivo visualization of pathological changes in the brain associated with the disease, providing a greater understanding of its pathophysiological development and progression. However, neuroimaging biomarkers do not yet offer clear advantages over current clinical diagnostic criteria for them to be accepted into routine clinical use. Nonetheless, current insights from neuroimaging combined with the elucidation of biochemical and molecular processes in AD are informing the ongoing development of new imaging techniques and their application. Much of this research has been greatly assisted by the availability of transgenic mouse models of AD. In this review we summarize the main efforts of neuroimaging in AD in humans and in mouse models, with a specific focus on β-amyloid, and discuss the potential of new applications and novel approaches.

Multi target neuroprotective and neurorestorative anti-Parkinson and anti-Alzheimer drugs ladostigil and m30 derived from rasagiline

Present anti-PD and -AD drugs have limited symptomatic activity and devoid of neuroprotective and neurorestorative property that is needed for disease modifying action. The complex pathology of PD and AD led us to develop several multi-target neuroprotective and neurorestorative drugs with several CNS targets with the ability for possible disease modifying activity. Employing the pharmacophore of our anti-parkinson drug rasagiline (Azilect, N-propagrgyl-1-R-aminoindan), we have developed a series of novel multi-functional neuroprotective drugs (A) [TV-3326 (N-propargyl-3R-aminoindan-5yl)-ethyl methylcarbamate)], with both cholinesterase-butyrylesterase and brain selective monoamine-oxidase (MAO) A/B inhibitory activities and (B) the iron chelator-radical scavenging-brain selective monoamine oxidase (MAO) A/B inhibitor and M30 possessing the neuroprotective and neurorescuing propargyl moiety of rasagiline, as potential treatment of AD, DLB and PD with dementia. Another series of multi-target drugs (M30, HLA-20 series) which are brain permeable iron chelators and potent selective brain MAO inhibitors were also developed. These series of drugs have the ability of regulating and processing amyloid precursor protein (APP) since APP and alpha-synuclein are metaloproteins (iron-regulated proteins), with an iron responsive element 5"UTR mRNA similar to transferring and ferritin. Ladostigil inhibits brain acetyl and butyrylcholinesterase in rats after oral doses. After chronic but not acute treatment, it inhibits MAO-A and -B in the brain. Ladostigil acts like an anti-depressant in the forced swim test in rats, indicating a potential for anti-depressant activity. Ladostigil prevents the destruction of nigrostriatal neurons induced by infusion of neurotoxin MPTP in mice. The propargylamine moiety of ladostigil confers neuroprotective activity against cytotoxicity induced by ischemia and peroxynitrite in cultured neuronal cells. The multi-target iron chelator M30 has all the properties of ladostigil and similar neuroprotective activity to ladostigil, but is not a ChE inhibitor. M30 has a neurorestorative activity in post-lesion of nigrostriatal dopamine neurons in MPTP, lacatcystin and 6-hydroxydopamine animal models of PD. The neurorestorative activity is related to the ability of the drug to activate hypoxia inducing factor (HIF) which induces the production of such neurotrophins as brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and erythropoietin as well as glia-derived neurotrophic factor (GDNF). The unique multiple actions of ladostigil and M30 make the potentially useful drugs for the treatment of dementia with Parkinsonian-like symptoms and depression.

Development and evaluation of a telehealth videoconferenced support group for rural spouses of individuals diagnosed with atypical early-onset dementias

Atypical and early-onset dementias can be particularly problematic for family caregivers, and support groups aimed at memory loss and Alzheimer’s disease are not always helpful. Unfortunately, little has been developed specifically for caregivers of individuals with atypical dementias such as the frontotemporal dementias. Compounding the lack of access to interventions targeted specifically at caregivers of individuals with atypical and early-onset dementias are the unique needs of rural caregivers. Due to the relative infrequency of these particular dementias and the large geographical distances between rural caregivers, technology-facilitation is required for any group-based intervention. This paper describes the development of a secure telehealth videoconferenced support group for rural spouses of individuals with atypical and early-onset dementias. In addition, we provide preliminary evidence of effectiveness and describe a template for future groups based on the key therapeutic aspects of this novel technology-facilitated intervention.

Beneficial effect of antibodies against β- secretase cleavage site of APP on Alzheimer's-like pathology in triple-transgenic mice

The toxicity of amyloid β and tau, the two hallmark proteins in Alzheimer's disease (AD), has been extensively studied individually. Recently new data suggest their possible interactions and synergistic effects in the disease. In this study, we investigate the ability of antibodies against the β secretase cleavage site on APP, named BBS1, to affect tau pathology, besides their well established effect on intracellular Aβ and amyloid load. For this purpose we treated the triple transgenic mice model of AD (3x Tg-AD) with mAb BBS1 intracerebroventricularly, using mini osmotic pumps for one month. The experimental data demonstrated reduction in total and phosphorylated tau levels, explained by significant reduction in GSK3β which phosphorylates tau on sites recognized by antibodies against PHF1 and AT-8. The treatment increased the cognitive capabilities and reduced the brain inflammation levels which accompany AD pathology. The data showing that tau pathology was significantly reduced by BBS1 antibodies suggest a close interaction between tau and Aβ in the development of AD, and may serve as an efficient novel immunotherapy against both hallmarks of this disease.

Behavioral disturbances in dementia

Psychological symptoms and behavioral abnormalities are common and prominent characteristics of dementia. They include symptoms such as depression, anxiety psychosis, agitation, aggression, disinhibition, and sleep disturbances. Approximately 30% to 90% of patients with dementia suffer from such behavioral disorders. There are complex interactions between cognitive deficits, psychological symptoms, and behavioral abnormalities. A large number of standardized, reliable, and well-validated instruments for assessing the behavioral and psychological symptoms of dementia have been developed in order to evaluate the efficacy of treatment. Neurodegenerative processes in various brain areas, particularly in the frontotemporal cortex and limbic regions, leading to cholinergic, serotonergic, and noradrenergic neurotransmitter dysfunctions constitute the biological matrix of behavioral symptoms, whereas psychological factors and personality traits play a modifying role. A large number of pharmacological, psychoeducational, psychotherapeutic, and social strategies have been developed to improve the quality of life of patients and their caregivers.

Mapping the structural brain changes in Alzheimer's disease: the independent contribution of two imaging modalities

The macrostructural atrophy of Alzheimer's disease (AD) has been fully described. Current literature reports that also microstructural alterations occur in AD since the early stages. However, whether the microstructural changes offer unique information independent from macrostructural atrophy is unclear. Aim of this study is to define the independent contribution of macrostructural atrophy and microstructural alterations on AD pathology. The study involved 17 moderate to severe AD patients and 13 healthy controls. All participants underwent conventional and non conventional MRI (respectively, T1-weighted and diffusion-weighted MR scanning). We processed the images in order to obtain gray and white matter volumes to assess macrostructural atrophy, and fractional anisotropy and mean diffusivity to assess the microstructural damage. Analyses of covariance between patients and controls were performed to investigate microstructural tissue damage independent of macrostructural tissue loss, and vice versa, voxel by voxel. We observed microstructural differences, independent of macrostructural atrophy, between patients and controls in temporal and retrosplenial regions, as well as in thalamus, corticopontine tracts, striatum and precentral gyrus. Volumetric differences, independent of microstructural alterations, were observed mainly in the entorhinal cortex, posterior cingulum, and splenium. Measures of microstructural damage provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD as well as in others thought to be spared. This work expands the understanding of the topography of pathological changes in AD that can be captured with imaging techniques.

Zinc ions promote Alzheimer Abeta aggregation via population shift of polymorphic states

Although a key factor in Alzheimer's disease etiology is enrichment of Zn(2+) in aggregates, and there are data suggesting that zinc promotes aggregation, how Zn(2+)-Abeta coordination promotes aggregation is elusive. Here we probe the structures and mechanisms through which Zn(2+) can affect amyloidosis. By covalently linking fragments (that have experiment-based coordinates) we observed that, in oligomeric Zn(2+)-Abeta(42), Zn(2+) can simultaneously coordinate intra- and intermolecularly, bridging two peptides. Zinc coordination significantly decreases the solvation energy for large Zn(2+)-Abeta(42) oligomers and thus enhances their aggregation tendency. Zn(2+) binding does not change the beta-sheet association around the C-terminal hydrophobic region; however, it shifts the relative population of the preexisting amyloid polymorphic ensembles. As a result, although a parallel beta-sheet arrangement is still preferred, antiparallel and other less structured assemblies are stabilized, also becoming major species. Overall, Zn(2+) coordination promotes Abeta(42) aggregation leading to less uniform structures. Our replica exchange molecular dynamics simulations further reproduced an experimental observation that the increasing Zn(2+) concentration could slow down the aggregation rate, even though the aggregation rates are still much higher than in Zn(2+)-free solution.

Microstructural diffusion changes are independent of macrostructural volume loss in moderate to severe Alzheimer's disease

Although it is established that Alzheimer's disease (AD) leads to cerebral macrostructural atrophy, microstructural diffusion changes have also been observed, but it is not yet known whether these changes offer unique information about the disease pathology. Thus, a multi-modal imaging study was conducted to determine the independent contribution of each modality in moderate to severe AD. Seventeen patients with moderate-severe AD and 13 healthy volunteers underwent diffusion-weighted and T1-weighted MR scanning. Images were processed to obtain measures of macrostructural atrophy (gray and white matter volumes) and microstructural damage (fractional anisotropy and mean diffusivity). Microstructural diffusion changes independent of macrostructural loss were investigated using an ANCOVA where macrostructural maps were used as voxel-wise covariates. The reverse ANCOVA model was also assessed, where macrostructural loss was the dependent variable and microstructural diffusion tensor imaging maps were the imaging covariates. Diffusion differences between patients and controls were observed after controlling for volumetric differences in medial temporal, retrosplenial regions, anterior commissure, corona radiata, internal capsule, thalamus, corticopontine tracts, cerebral peduncle, striatum, and precentral gyrus. Independent volumetric differences were observed in the entorhinal cortex, inferior temporal lobe, posterior cingulate cortex, splenium and cerebellum. While it is well known that AD is associated with pronounced volumetric change, this study suggests that measures of microstructure provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD and in those thought to be spared. As such this work provides great understanding of the topography of pathological changes in AD that can be captured with imaging.

Memantine improves cognition and reduces Alzheimer's-like neuropathology in transgenic mice

Memantine is an N-methyl-d-aspartate receptor antagonist that is approved for the treatment of moderate to severe Alzheimer's disease (AD). In this study, three groups of triple-transgenic (3xTg-AD) mice with differing levels of AD-like pathology (6, 9, and 15 months of age) were treated for 3 months with doses of memantine equivalent to those used in humans. After the treatment, memantine-treated mice had restored cognition and significantly reduced the levels of insoluble amyloid-beta (Abeta), Abeta dodecamers (Abeta*56), prefibrillar soluble oligomers, and fibrillar oligomers. The effects on pathology were stronger in older, more impaired animals. Memantine treatment also was associated with a decline in the levels of total tau and hyperphosphorylated tau. Finally, memantine pre-incubation prevented Abeta-induced inhibition of long-term potentiation in hippocampal slices of cognitively normal mice. These results suggest that the effects of memantine treatment on AD brain include disease modification and prevention of synaptic dysfunction.

Changes in everyday function in individuals with psychometrically defined mild cognitive impairment in the Advanced Cognitive Training for Independent and Vital Elderly Study

OBJECTIVES

To examine trajectories of change in everyday function for individuals with cognitive deficits suggestive of mild cognitive impairment (MCI).

DESIGN

Using data from the longitudinal, multisite Advanced Cognitive Training for Independent and Vital Elderly Study allowed for post hoc classification of MCI status at baseline using psychometric definitions for amnestic MCI, nonamnestic MCI, multidomain MCI, and no MCI.

SETTING

Six U.S. cities.

PARTICIPANTS

Two thousand eight hundred thirty-two volunteers (mean age 74; 26% African American) living independently, recruited from senior housing, community centers, hospitals, and clinics.

MEASUREMENTS

Mixed-effect models examined changes in self-reported activities of daily living and instrumental activities of daily living (IADLs) from the Minimum Data Set Home Care Interview in 2,358 participants over a 3-year period.

RESULTS

In models for IADL performance, IADL difficulty, and a daily functioning composite, there was a significant time by MCI classification interaction for each MCI subtype, indicating that all MCI groups showed faster rates of decline in everyday function than cognitively normal participants with no MCI.

CONCLUSION

Results demonstrate the importance of MCI as a clinical entity that not only predicts progression to dementia, but also predicts functional declines in activities that are key to autonomy and quality of life. MCI classification guidelines should allow for functional changes in MCI, and clinicians should monitor for such changes. Preservation of function may serve as a meaningful outcome for intervention efforts.

Health problems and correlates of pain in nursing home residents with advanced dementia

This study describes the health problems and comorbid illnesses of nursing home (NH) residents with advanced dementia (n=123) and identifies correlates of staff-identified pain. Study participants were residents of 3 NHs in Maryland, their surrogate decision makers and their physicians. Residents' cognitive function was assessed at study enrollment, and their medical records were reviewed to identify all health problems/illnesses and use of pain medications during the 6 months before their enrollment. The most prevalent health problems were skin problems (95%), nutrition/hydration problems (85%), psychiatric/behavioral problems (85%), gastrointestinal problems (81%), and infections (80%). Sixty-three percent of residents had recognized pain, and 95% of those residents received pain medications. In a multivariate regression analysis, staff-identified pain was associated with aspiration (P=0.008), peripheral vascular disease (P=0.021), musculoskeletal disorders (P=0.032), higher cognitive function (P=0.013), and use of pain medications, including non-opiates (P=0.004) and the combination of opiates and non-opiates (P=0.001). NH residents with advanced dementia experience a complex mixture of multiple chronic and acute comorbidities. These results suggest the need for clinicians in long-term care facilities to be vigilant in assessing and treating pain, particularly as cognitive function declines in those with advanced dementia.

Linkage and association studies identify a novel locus for Alzheimer disease at 7q36 in a Dutch population-based sample

We obtained conclusive linkage of Alzheimer disease (AD) with a candidate region of 19.7 cM at 7q36 in an extended multiplex family, family 1270, ascertained in a population-based study of early-onset AD in the northern Netherlands. Single-nucleotide polymorphism and haplotype association analyses of a Dutch patient-control sample further supported the linkage at 7q36. In addition, we identified a shared haplotype at 7q36 between family 1270 and three of six multiplex AD-affected families from the same geographical region, which is indicative of a founder effect and defines a priority region of 9.3 cM. Mutation analysis of coding exons of 29 candidate genes identified one linked synonymous mutation, g.38030G-->C in exon 10, that affected codon 626 of the PAX transactivation domain interacting protein gene (PAXIP1). It remains to be determined whether PAXIP1 has a functional role in the expression of AD in family 1270 or whether another mutation at this locus explains the observed linkage and sharing. Together, our linkage data from the informative family 1270 and the association data in the population-based early-onset AD patient-control sample strongly support the identification of a novel AD locus at 7q36 and re-emphasize the genetic heterogeneity of AD.

Screening for mild cognitive impairment in elderly ambulatory patients with cognitive complaints

BACKGROUND AND AIMS

Identification of patients with Mild Cognitive Impairment (MCI) is strongly recommended because of their increased risk of dementia. Two brief global cognitive instruments, the Mini Mental State Examination (MMSE) and the Clock Drawing Test (CDT), were examined as useful screening methods for MCI.

METHODS

The sensitivity and specificity of MMSE and CDT, scored using the Sunderland and Wolf-Klein methods, were evaluated in 113 elderly individuals with three different MCI subtypes: amnestic, multiple domain impairments, and single non-memory domain. Diagnoses were made on the basis of extensive clinical and neuropsychometric assessment.

RESULTS

Used alone, MMSE and CDT at standard cut-offs were highly specific (about 0.80) but rather insensitive (less than 0.50) to all MCI subtypes. By contrast, when used in combination, an abnormal result on either MMSE or CDT scored by the Sunderland method had a specificity of 0.69 [0.57-0.81] and a sensitivity of 0.75 [0.64-0.87] for multiple domain impairments MCI. Results were similar for MMSE in combination with CDT scored by the Wolf-Klein method (specificity 0.71 [0.59-0.83]; sensitivity 0.68 [0.56-0.80]).

CONCLUSIONS

MMSE and CDT alone are not valid screening methods for MCI detection. In combination, they reach fair sensitivity and specificity for the multiple domain impairment MCI subtype. However, some theoretical concerns relating to this subtype, together with the uncertainty that still lingers about its prognostic value, caution against routine use of MMSE and CDT as MCI screening instruments.

Mitochondrial respiratory chain in brain homogenates: activities in different brain areas in patients with Alzheimer's disease

BACKGROUND AND AIMS

The potential influence of impaired oxidative metabolism in the modulation of manifestations in sporadic Alzheimer's disease (AD) has attracted much attention in the last 50 years. Unfortunately, many clinical and experimental results aiming at proving this hypothesis are still controversial. The aim was to study the enzymatic activities of respiratory chain (RC) complexes I through V in three brain areas of a group of patients with definite AD, and to compare the results with a group of normal brains. We simultaneously assessed the lipid peroxidation of the samples as a measure of free radical damage.

METHODS

The specific activity of the individual complexes of the RC was measured spectrophotometrically, and the loss of cis-parinaric acid fluorescence was used to determine the chemical process of lipid peroxidation.

RESULTS

We were not able to detect differences in any of the analyzed RC enzymatic activities, or in the level of lipid peroxidation between patients with AD and controls. Instead, differences were found in the number of mitochondria and in the intrinsic enzymatic activities of complexes III and IV in various brain areas.

CONCLUSIONS

Spectrophotometric enzymatic analyses of respiratory complexes in brain homogenates do not support the primary contribution of mitochondrial RC dysfunction in the pathogenesis of AD.

Medical management of advanced dementia

A cure for Alzheimer's disease (AD) is still far off, and clinicians face the burden of caring for patients at all stages of dementia for the foreseeable future. Those with advanced disease suffer neurological symptoms and signs that include incontinence; problems with gait and mobility; marked cognitive, language, and functional impairment; and in about 90% of patients, significant behavior problems. Dementia precludes the ability to initiate meaningful activities or social interactions. Whether patients are resident in the community or living in a nursing home, this composite reflects a highly complex medical and neuropsychiatric management challenge. Predictable medical conditions also must be addressed (i.e., those that accompany dementia, such as parkinsonism, and those that are prevalent in any aging population, such as hypertension). Clinicians can better address these problems with awareness of current treatment options. Placebo-controlled trials of some psychotropic agents have shown modest favorable effects on behavior problems. Use of acetylcholinesterase inhibitors (AChEIs) to treat cognitive impairment and secondary behavioral symptoms derives primarily from results of placebo-controlled clinical trials. Trials in patients with moderate to severe AD, outpatients as well as nursing home residents, show overall effects similar to those seen in outpatients with milder dementia. Treatment with AChEIs may delay institutional placement. Memantine has shown benefit in trials in moderate to severe dementia, although it is not yet approved in the United States. Emerging data have expanded physicians' ability to use pharmacotherapy in patients with advanced dementia. Physicians need to enact the principle that something can be done for our afflicted parents and grandparents.

Early diagnosis of Alzheimer's disease: clinical and economic benefits

An estimated four million individuals in the United States have Alzheimer's disease (AD). This number is expected to more than triple by mid-century. Primary care physicians have a key role in evaluating older patients for early signs of dementia and in initiating treatment that can significantly retard its progression over the maximum period of time. That role and its challenges will inevitably grow along with the expected increase in the population aged 65 and older. The tendency for physicians to dismiss memory complaints as normal aging must be replaced by awareness of the need to assess and possibly intervene. Early intervention is the optimal strategy, not only because the patient's level of function will be preserved for a longer period, but also because community-dwelling patients with AD incur less societal cost than those who require long-term institutional placement. Institutionalization contributes heavily to the annual cost of care for AD in the United States, which is estimated to be 100 billion dollars annually.

A meta-analysis of structural and functional brain imaging in dementia of the Alzheimer's type: a neuroimaging profile

We conducted a quantitative review of the imaging literature using meta-analytic methodology to characterize further the magnitude of hippocampal deficit in probable Alzheimer's disease (AD) and to determine whether other neuroanatomic structures in AD can better discriminate the disease from normal aging. Additionally, we parceled the discriminability of neuroanatomic structures by duration of disease to determine those structures most sensitive to AD in its early and late stages. One hundred twenty-one studies published between 1984 and 2000 met criteria for inclusion in the present analysis. In total, structural (i.e., CT and MRI) and functional (i.e., SPECT and PET) neuroimaging results from 3511 patients with AD, and 1632 normal healthy controls were recorded across meta-analyses. Our results include neuroimaging profiles for both early onset and longer duration patients with AD. In sum, these profiles yield a signature of diagnostic markers in both cortical and subcortical neuroanatomic areas. This signature is consistent with the clinical phenomenology of Alzheimer's dementia and should aid in the positive identification of AD.

The impact of mild cognitive impairment on functional abilities in the elderly

Mild cognitive impairment (MCI) covers a spectrum of cognitive impairment, bordered by normal cognitive performance on one end and frank dementia on the other. How wide the net for MCI is cast will affect the prevalence and severity of its functional consequences. Many studies suggest that MCI is an early stage of Alzheimer's disease. Therefore, investigation of the functional impact of MCI offers an important opportunity to examine the quality-of-life impact of a prodromal stage of Alzheimer's disease. In this review, the authors examine the nosology of the condition, the subjective experience of having an MCI diagnosis, and cross- sectional and prospective studies that have examined the topic.

In what extent anemia coexists with cognitive impairment in elderly: a cross-sectional study in Greece

BACKGROUND

A project aimed at studying the frequency of dementia and depression in the catchment area of the Health Centre of Chrissoupolis (HCCh), Northern Greece, was carried out. This paper reports the association between AD and anemia among the elderly participants in this Greek study.

METHODS

Eligible participants were people 65 years or over who were (a) living in the Elderly People's Home (all 48 subjects included); (b) visiting the Open Center for Elderly People during a 20 workday period (75 subjects) and (c) visiting the HCCh for routine medical care. The Mini Mental State Examination (MMSE) was used in assessing the cognitive capacity of the participants. Blood was drawn for serum hematocrit, vitamin B12 and folate determination.

RESULTS

The prevalence proportions of possible cognitive impairment among anemic and non-anemic males were 55.6% and 34.4%, respectively (X2 = 5.8, d.f. = 1, p = 0.016). The corresponding proportions in females were 47.5% and 40.1 % (X2 = 1.1, d.f. = 1, p = 0.305). Using logistic regression analysis, age-group (>or= 80 yrs), type of Institute, vitamin B12 and anemia had significant independent associations with possible cognitive impairment.

CONCLUSIONS

Anemia is a frequent finding in elderly and it may be a risk factor for dementia, but the extent of the associated deterioration of cognitive impairment or the relation with AD is not known. GPs should be aware of this coexistence and recommend for screening, assaying and treating elderly people.