https://www.unsv.com/upload/2011/12/20/733309-260748385437.pdf

Pathological roles of MAPK signaling pathways in human diseases

Alzheimer's disease is one of the most common causes of mental deterioration in elderly people, accounting for around 50%-60% of the overall cases of dementia among persons over 65 years of age. The past two decades have witnessed a considerable research effort directed towards discovering the cause of Alzheimer's disease with the ultimate hope of developing safe and effective pharmacological treatments. This article examines the existing scientific applicability of the original cholinergic hypothesis of Alzheimer's disease by describing the biochemical and histopathological changes of neurotransmitter markers that occur in the brains of patients with Alzheimer's disease both at postmortem and neurosurgical cerebral biopsy and the behavioural consequences of cholinomimetic drugs and cholinergic lesions. Such studies have resulted in the discovery of an association between a decline in learning and memory, and a deficit in excitatory amino acid (EAA) neurotransmission, together with important roles for the cholinergic system in attentional processing and as a modulator of EAA neurotransmission. Accordingly, although there is presently no "cure" for Alzheimer's disease, a large number of potential therapeutic interventions have emerged that are designed to correct loss of presynaptic cholinergic function. A few of these compounds have confirmed efficacy in delaying the deterioration of symptoms of Alzheimer's disease, a valuable treatment target considering the progressive nature of the disease. Indeed, three compounds have received European approval for the treatment of the cognitive symptoms of Alzheimer's disease, first tacrine and more recently, donepezil and rivastigmine, all of which are cholinesterase inhibitors.

https://jnnp.bmj.com/content/jnnp/66/2/137.full.pdf

The cholinergic hypothesis of Alzheimer’s disease: a review of progress

Article abstract—Objective: To update the 1994 practice parameter for the diagnosis of dementia in the elderly. Background: The AAN previously published a practice parameter on dementia in 1994. New research and clinical developments warrant an update of some aspects of diagnosis. Methods: Studies published in English from 1985 through 1999 were identified that addressed four questions: 1) Are the current criteria for the diagnosis of dementia reliable? 2) Are the current diagnostic criteria able to establish a diagnosis for the prevalent dementias in the elderly? 3) Do laboratory tests improve the accuracy of the clinical diagnosis of dementing illness? 4) What comorbidities should be evaluated in elderly patients undergoing an initial assessment for dementia? Recommendations: Based on evidence in the literature, the following recommendations are made. 1) The DSM-III-R definition of dementia is reliable and should be used (Guideline). 2) The National Institute of Neurologic, Communicative Disorders and Stroke‐AD and Related Disorders Association (NINCDS-ADRDA) or the Diagnostic and Statistical Manual, 3rd edition, revised (DSM-IIIR) diagnostic criteria for AD and clinical criteria for Creutzfeldt‐Jakob disease (CJD) have sufficient reliability and validity and should be used (Guideline). Diagnostic criteria for vascular dementia, dementia with Lewy bodies, and frontotemporal dementia may be of use in clinical practice (Option) but have imperfect reliability and validity. 3) Structural neuroimaging with either a noncontrast CT or MR scan in the initial evaluation of patients with dementia is appropriate. Because of insufficient data on validity, no other imaging procedure is recommended (Guideline). There are currently no genetic markers recommended for routine diagnostic purposes (Guideline). The CSF 14-3-3 protein is useful for confirming or rejecting the diagnosis of CJD (Guideline). 4) Screening for depression, B12 deficiency, and hypothyroidism should be performed (Guideline). Screening for syphilis in patients with dementia is not justified unless clinical suspicion for neurosyphilis is present (Guideline). Conclusions: Diagnostic criteria for dementia have improved since the 1994 practice parameter. Further research is needed to improve clinical definitions of dementia and its subtypes, as well as to determine the utility of various instruments of neuroimaging, biomarkers, and genetic testing in increasing diagnostic accuracy.

https://n.neurology.org/content/neurology/56/9/1143.full.pdf

Practice parameter: Diagnosis of dementia (an evidence-based review) Report of the Quality Standards Subcommittee of the American Academy of Neurology

The efficacy and safety of donepezil as a treatment for patients with mild to moderate Alzheimer's disease (AD) was investigated in a multicenter, double-blind study. Patients were randomly assigned to treatment with placebo (n = 162), 5 mg/d donepezil (n = 154), or 10 mg/d donepezil (n = 157) for 24 weeks followed by a 6-week, single-blind placebo washout. The primary efficacy measures were the cognitive portion of the Alzheimer's Disease Assessment Scale (ADAS-cog) and the Clinician's Interview Based Assessment of Change-Plus (CIBIC plus), with the Mini-Mental State Examination (MMSE), Clinical Dementia Rating Scale-Sum of the Boxes (CDR-SB), and patient rated Quality of Life (QoL) used as secondary measures. Cognitive function, as measured by the ADAS-cog, was significantly improved in the 5- and 10-mg/d donepezil groups as compared with the placebo group at weeks 12, 18, and 24. Clinician's global ratings on the CIBIC plus also improved in both the 5- and 10-mg/d donepezil groups relative to placebo. At the end of the 6-week placebo washout phase, ADAS-cog scores and CIBIC plus ratings were not significantly different for the three groups. Significant treatment benefits were also observed consistently in both the 5- and 10-mg/d groups on the MMSE and the CDR-SB, but there was no consistent effect on the patient-rated QoL. Cholinergic side effects (primarily diarrhea, nausea, and vomiting) were reported more often in the 10-mg/d group than either the 5-mg/d or placebo groups. Side effects were transient and generally mild in severity. These data indicate that donepezil is a well-tolerated drug that improves cognition and global function in patients with mild to moderate AD.

A 24-week, double-blind, placebo-controlled trial of donepezil in patients with Alzheimer's disease

The 'Hawthorne Effect' may be an important factor affecting the generalisability of clinical research to routine practice, but has been little studied. Hawthorne Effects have been reported in previous clinical trials in dementia but to our knowledge, no attempt has been made to quantify them. Our aim was to compare minimal follow-up to intensive follow-up in participants in a placebo controlled trial of Ginkgo biloba for treating mild-moderate dementia. Participants in a dementia trial were randomised to intensive follow-up (with comprehensive assessment visits at baseline and two, four and six months post randomisation) or minimal follow-up (with an abbreviated assessment at baseline and a full assessment at six months). Our primary outcomes were cognitive functioning (ADAS-Cog) and participant and carer-rated quality of life (QOL-AD). We recruited 176 participants, mainly through general practices. The main analysis was based on Intention to treat (ITT), with available data. In the ANCOVA model with baseline score as a co-variate, follow-up group had a significant effect on outcome at six months on the ADAS-Cog score (n = 140; mean difference = -2.018; 95%CI -3.914, -0.121; p = 0.037 favouring the intensive follow-up group), and on participant-rated quality of life score (n = 142; mean difference = -1.382; 95%CI -2.642, -0.122; p = 0.032 favouring minimal follow-up group). There was no significant difference on carer quality of life. We found that more intensive follow-up of individuals in a placebo-controlled clinical trial of Ginkgo biloba for treating mild-moderate dementia resulted in a better outcome than minimal follow-up, as measured by their cognitive functioning. Current controlled trials: ISRCTN45577048

/pdf/the-hawthorne-effect-a-randomised-controlled-trial-4b372i859g.pdf

The Hawthorne Effect: a randomised, controlled trial

Senile dementia of the Alzheimer type (SDAT) is a degenerative disease of the brain that affects up to 20% or more of individuals who live beyond 80 years of age. A deficiency of cholinergic function is expected to play a major role in the development of SDAT psychopathology. Possible existence of an underactive cholinergic system has led to clinical trials of cholinomimetic drugs to attempt to reverse the deficit in SDAT. Some improvement in memory function has followed the administration of cholinesterase (ChE) inhibitors, but in general the affected individuals have not been returned to normal or mildy impaired mental functions or activities of daily living functioning. This paper is a critical review of results of acute and chronic trials performed with ChE inhibitors in experimental animals and humans. We also review and discuss mechanisms of decvelopment of pharmacological behavioral tolerance to ChE inhibitors. Behavioral changes following ChE inhibition appear to coincide with predicted peak levels of acetulcholine (ACh) concentration in the brain. Yet we find an inconsistent relationship among the degree of ChE inhibition, changes in brain acetylcholine concentrations, and behavioral changes, both therapeutic and adverse effects, following administration of ChE inhibitors. ChE inhibition is associated with distressing adverse effects. The therapeutic effects of increased ACh levels in the brain may be masked by these side effects. We suggest that an adequate test of the efficacy of ChE inhibition may await the use of new and improved ChE inhibitors that produce significantly fewer side effects and greater therapeutic effects than drugs presently being tested for efficacy in the treatment of SDAT patients.

Mechanisms of cholinesterase inhibition in senile dementia of the alzheimer type: Clinical, pharmacological, and therapeutic aspects

Cholinergic Basis for Alzheimer Therapy

Depressive syndromes that occur during the course of schizophrenia are not clearly understood but have important implications for the treatment of the schizophrenic patient. In this review of the literature on depression secondary to schizophrenia, the author notes that lack of tested diagnostic criteria has led to a misunderstanding of its relatively high frequency and its association with poor outcome features such as impaired psychosocial functioning, schizophrenic relapse, and suicide. Differential diagnosis, including ruling out akinetic depression, is essential, he believes, partly because the concept of schizophrenic depression as postpsychotic is not supported by evidence. Clinical management must address such increased risk factors as relapse and suicide, but evidence indicates that secondary depression in schizophrenia does not respond to antidepressant medication.

Depression in schizophrenia.

Following the introduction of cholinesterase inhibitors in 1986 and a 20-yr long period of successful clinical application in mild, moderate and severe patients, the treatment of AD has turned to modify the course of pathological processes thought to comprise the disease. Several active and passive vaccines are presently under investigation for efficacy, reducing amyloid-beta in the brain of patients with mild-moderately advanced disease. Three large international immunization trials are in progress in US and Europe on mild-moderate AD patients. Among these, the most advanced trial in time is the humanized antibody trial. In addition, drugs aiming to reduce tau phosphorylation (GSK3 inhibitors) are about to enter clinical phases of development. Due to intrinsic difficulties, the developments of gamma-and beta-secretase inhibitors have not yet reached clinical stages. Only one anti-amyloid-aggregation, an aminoglycan compound, and one anti-APO-E approach with rosiglitazone are currently in clinical testing. Stem-cell therapy and gene-replacing therapy remain experimental and far from clinical application. Based on experimental evidence that NGF (nerve growth factor) treatment could provide prolonged protection of the central cholinergic system, i.c.v. infusion of NGF, with genetically modified fibroblasts or gene therapy are under current investigation. NGF treatment could probably double the clinical effect of ChEIs in time. Given the level of scientific and clinical activity it is reasonable to expect that within the next five to ten years a new therapy for AD will, by blocking disease progression, both produce long term stabilization of at least 5 years in patients with AD and prevent or delay emergence in persons at risk for AD.

One hundred years after the discovery of Alzheimer's disease. A turning point for therapy?

Fifty patients with probable Alzheimer disease (AD) completed a 3-month double-blind study to compare metrifonate to placebo. We dosed metrifonate to achieve a 40-60% inhibition of red blood cell acetylcholinesterase activity. The Alzheimer Disease Assessment Scale cognitive subscale score (ADAS-C) served as the primary outcome measure. At the completion of 3 months of treatment, the metrifonate group ADAS-C score differed significantly from the placebo group score by 2.6 points (p < 0.01). A 0.75-point trend toward improvement occurred during treatment in the ADAS cognitive performance of the metrifonate group (p = 0.15), and a 1.10-point deterioration in cognitive performance was found in the placebo group (p < 0.02). On the Global Improvement Scale (GIS), the two groups differed significantly on their changes from baseline to treatment phase (p < 0.02). Significant deterioration occurred in GIS scores (p < 0.01) and in Mini Mental State Examination (MMSE) scores (p < 0.03) in the placebo-treated group. Adverse effects were uncommon and did not require adjustment of the dose of metrifonate or discontinuation of treatment. We achieved a mean of 52.3% decrease in red blood cell acetylcholinesterase activity. During up to 18 months of subsequent open metrifonate treatment of patients, we found a deterioration of 1.68 points per year in MMSE performance. These findings support further study of the effects of metrifonate on deterioration rate in AD.

Robert E. Becker

Papers

Mechanisms of cholinesterase inhibition in senile dementia of the alzheimer type: Clinical, pharmacological, and therapeutic aspects

Cholinergic Basis for Alzheimer Therapy

Depression in schizophrenia.

One hundred years after the discovery of Alzheimer's disease. A turning point for therapy?

Double-blind, placebo-controlled study of metrifonate, an acetylcholinesterase inhibitor, for Alzheimer disease.