Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The defining characteristic of Alzheimer's disease is cognitive impairment, but commonly this impairment is accompanied by mood and behavioral symptoms such as depression, anxiety, irritability, inappropriate behavior, sleep disturbance, psychosis, and agitation. The symptoms of Alzheimer's disease are not normative to the aging process. Diagnosis of Alzheimer's disease in the majority of cases can be made with confidence through office-based clinical assessment and informant interview. Alzheimer's disease is the most common of the dementing disorders and is exponentially increasing in incidence, projected to affect 8.64 million people in the United States by the year 2047. At present, no treatment can prevent or cure Alzheimer's disease, and the fact that Alzheimer's affects a geriatric population makes treatment all the more challenging. Therapies that could delay onset of symptoms even briefly would have a major impact on public health. As the prevalence of Alzheimer's disease increases, researchers are examining the efficacy of treatment options beyond the realm of the established cholinesterase inhibitors.
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PMID:Diagnosis and treatment of Alzheimer's disease. 1293 67

The ability of phencyclidine (PCP), a noncompetitive antagonist of NMDA receptor-mediated neurotransmission, to precipitate a schizophreniform psychosis in susceptible individuals is consistent with the hypothesized pathologic occurrence of NMDA receptor hypofunction in this disorder. Because the psychosis caused by PCP resembles schizophrenia in all of the relevant domains of psychopathology, investigators have sought to characterize animal models of NMDA receptor hypofunction. MK-801 (dizocilpine) binds to the same hydrophobic channel domain in the NMDA receptor-associated ionophore as PCP, and has been shown to elicit intense irregular episodes of jumping behavior in mice, termed "popping." MK-801-elicited mouse popping is an animal model of NMDA receptor hypofunction that has been used to screen novel candidate compounds for the treatment of schizophrenia. Recently, a selective abnormality in the transduction of the acetylcholine signal at the level of the alpha 7 nicotinic receptor has been described in schizophrenia. The existence of a nicotinic cholinergic abnormality in schizophrenia has stimulated interest in a potential therapeutic role for positive allosteric modulation of nicotinic receptors. Galantamine is a compound that possesses two interesting properties: inhibition of acetylcholinesterase and positive allosteric modulation of nicotinic neurotransmission. Theoretically, galantamine would be expected to increase the efficiency or likelihood that acetylcholine will promote channel opening and ionic conductance at nicotinic receptors. As expected, in the current investigation statistically significant popping behavior was elicited by MK-801 in mice (T(22) = 2.16, P < 0.05). This MK-801-elicited popping was significantly attenuated by 100 mg/kg of galantamine (T(22) = 2.24, P < 0.05). The data show that nicotinic interventions can influence NMDA receptor-mediated neurotransmission in the intact mouse.
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PMID:Modulation of MK-801-elicited mouse popping behavior by galantamine is complex and dose-dependent. 1294 37

Although disturbed memory function often coexists with psychosis, the cognitive effects of antipsychotic medications with diverse pharmacodynamic properties are rarely investigated. The neurocognitive profile of zuclopenthixol, a thioxanthene dopaminergic antagonist and a conventional neuroleptic agent, has yet to be investigated despite the effect of the drug on a variety of neurotransmitter systems involved in mediation of learning and memory processes. In this study, the effect of zuclopenthixol was tested on memory retrieval 24 h after training using an inhibitory avoidance task in rats. Acute administration of zuclopenthixol (0.7 and 1.4 mg/kg i.p.) before retrieval testing increased step-through latency during the test session. The same doses of zuclopenthixol did not affect the ambulatory activity of rats in the openfield test and therefore the facilitatory effect of the drug on memory function could not be confounded with any motoric properties. This study also investigated the effect of zuclopenthixol on cortical and hippocampal monoaminergic neurotransmitters' levels together with acetylcholinesterase enzyme (AChE) activity, both of which are known to be important in control of cognitive function. Administration of zuclopenthixol (0.7 and 1.4 mg/kg i.p.) neither affected dopamine (DA) level nor AChE activity in rat cortex and hippocampus. On the other hand, the lower dose of zuclopenthixol elevated cortical norepinephrine (NE) level, while the higher dose elevated both cortical and hippocampal NE level together with hippocampal serotonin (5-HT) level. These results may suggest the involvement of adrenergic and serotonergic mechanisms in the facilitatory effect of zuclopenthixol on retrieval memory. Zuclopenthixol may therefore be a better alternative than other commonly used antipsychotic medications reported to impair cognitive function of schizophrenic patients.
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PMID:Zuclopenthixol facilitates memory retrieval in rats: possible involvement of noradrenergic and serotonergic mechanisms. 1295 16

Dementia in Parkinson's disease (PDD) is a frequent and distressing complication with major consequences. Clinical and pathological features closely link PDD and dementia with Lewy bodies (DLB), suggesting they represent part of the same disease spectrum. Although dopaminergic deficiency primarily determines the akinetic-rigid symptoms of PDD and DLB, there is overwhelming evidence that cholinergic dysfunction underpins many of the cognitive impairments and psychotic features. Open-label studies have suggested that cholinesterase inhibitor drugs may exert positive effects upon all aspects of the neuropsychiatric syndrome in PDD and DLB but particularly apathy, anxiety, impaired attention, hallucinations, delusions, sleep disturbance, and cognitive test performance. Worsening of extrapyramidal motor features is reported only rarely. Initial double-blind, placebo-controlled studies in PDD and DLB have so far confirmed these encouraging results. Early identification of PD patients at greatest risk of developing dementia would permit early use of disease modifying treatments which represent the "golden fleece" management approach to these groups.
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PMID:Current treatment of dementia with Lewy bodies and dementia associated with Parkinson's disease. 1450 59

Psychosis is common in patients with Alzheimer's disease (AD) and contributes substantially to patient morbidity and caregiver distress. Antipsychotic medications are used to treat psychosis and other psychiatric or behavioral symptoms in AD, although optimal treatment guidelines have been elusive. Choosing the most advantageous medication for an individual patient is challenging. This article provides an overview of clinical management principles and medication treatment strategies for patients with AD and psychosis. Effects of individual medications are also described. Medications in the conventional neuroleptic, atypical antipsychotic, cholinesterase inhibitor, and serotonergic classes have been shown to ameliorate psychosis and behavioral symptoms in patients with AD, although the evidence is not conclusive for many medications. Side effects vary substantially across medication classes and modestly among individual patients. Improvement in agitation, aggression, or other behaviors with antipsychotic medication treatment may not depend on distinct antipsychotic effects. In contrast, there is preliminary evidence that delusions and hallucinations may respond to treatment with medications outside the antipsychotic class. Many important clinical questions warrant further research study. In particular, studies to compare how individual symptoms respond to different medications, and to examine how to best manage overlapping symptoms or incomplete treatment response are needed.
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PMID:Psychosis and antipsychotic medications in Alzheimer's disease: clinical management and research perspectives. 1456

The syndrome of dementia with Lewy bodies (DLB) is characterised by the clinical triad of fluctuating cognitive impairment, recurrent visual hallucinations and spontaneous motor features of Parkinsonism. In an attempt to define DLB as a distinct clinical syndrome separate from Alzheimer's disease (AD) and Parkinson's disease (PD) with dementia, a consensus workshop in 1995 established a new set of diagnostic criteria. Dementia that precedes or accompanies the onset of spontaneous (i.e., not neuroleptic-induced) Parkinsonism is termed DLB. In addition, fluctuations in alertness, cognition and function and visual hallucinations are emphasised and included as core features of DLB. The degree to which an individual patient exhibits cognitive impairment, behavioural problems and Parkinsonian features is variable. Therefore, treatment must be individualised. Although there are no officially approved drugs for DLB, limited experience from clinical trials, as well as past experience with the treatment of AD and PD patients, provide some basis for making drug choices. The cholinergic deficit seen in DLB makes cholinesterase inhibitor drugs the mainstay of treatment for cognitive impairment. This class of drugs has also shown therapeutic benefit in reducing hallucinations and other neuropsychiatric symptoms of the disease. Because of their relatively greater therapeutic window, cholinesterase inhibitors are also used as first-line therapy for the treatment of psychosis in DLB. Patients with DLB are extremely sensitive to the extrapyramidal side effects of neuroleptic medications. Thus, only atypical antipsychotic agents such as quetiapine, should be considered as alternative treatment for psychosis. Anxiety and depression are best treated with selective serotonin re-uptake inhibitors, whereas REM sleep behaviour disorder may be treated with low dose clonazepam. Parkinsonism responds to dopaminergic agents; however, precipitation or aggravation of hallucinosis may occur. Levodopa is preferred over dopamine agonists due to its lower propensity to cause hallucinations and somnolence. As the diagnostic criteria for DLB become more refined and validated by postmortem studies, it is hoped that rigorous, well-designed trials will be performed, aimed at alleviating the primary target symptoms of dementia, psychosis and Parkinsonism.
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PMID:Pharmacotherapy of dementia with Lewy bodies. 1459 56

Cholinesterase inhibitors are commonly used to improve cognition and treat psychosis and other behavioral symptoms in Alzheimer's disease, Parkinson's disease, and other neuropsychiatric conditions. However, mechanisms may exist that down-regulate the synaptic response to altered cholinergic transmission, thus limiting the efficacy of cholinomimetics in treating disease. Acetylcholinesterase knockout (AChE-/-) mice were used to investigate the neuronal adaptations to diminished synaptic acetylcholine (ACh) metabolism. The striatum of AChE-/- mice showed no changes in choline acetyltransferase activity or levels of the vesicular ACh transporter but showed striking 60% increases in the levels of the highaffinity choline transporter. This transporter takes choline from the synapse into the neuron for resynthesis of ACh. In addition, the striata of AChE-/- mice showed dramatic reductions in levels of the M1, M2, and M4 muscarinic ACh receptors (mAChRs), but no alterations in dopamine receptors or the beta2 subunit of nicotinic receptors. M1, M2, and M4 also showed decreased dendritic and cell surface distributions and enhanced intracellular localizations in striatal neurons of AChE-/- mice. mAChR antagonist treatment reversed the shifts in mAChR distribution, indicating that internalized receptors in AChE-/- mice can recover to basal distributions. Finally, AChE-/- mice showed increased sensitivity to mAChR antagonist-induced increases in locomotor activity, demonstrating functional mAChR down-regulation. mAChR downregulation in AChE-/- mice has important implications for the long-term use of cholinesterase inhibitors and other cholinomimetics in treating disorders characterized by perturbed cholinergic function.
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PMID:Altered striatal function and muscarinic cholinergic receptors in acetylcholinesterase knockout mice. 1464 60

We aimed to determine whether the cholinesterase inhibitor rivastigmine, an inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), would improve quality of life and cognitive function in 16 clinically stable subjects affected by schizophrenia in the residual phase. Study subjects began rivastigmine treatment at a dose of 1.5 mg bid. This dose was escalated at monthly intervals in increments of 1.5 mg bid to a maximum of 6 mg bid. All subjects were followed for 12 months. Quality of life was assessed using the Satisfaction with Life Domains Scale (SLDS, a self-report scale containing 10 "satisfaction" items); cognitive function, attentional function, and aspects of learning and memory were evaluated using common neuropsychological tests. Psychopathology was evaluated by means of the Brief Psychiatric Rating Scale (BPRS). Rivastigmine treatment resulted in significant improvements in quality of life, which were paralleled by significant improvements in cognitive function, learning and memory, and trends for improvement in attention. The BPRS factor "anergia" showed significant improvement, while low baseline scores in other psychotic factors did not permit further improvements. There were no reports of nausea or vomiting. In conclusion, rivastigmine significantly improved quality of life in subjects with schizophrenia. These benefits may relate to the drug's effects on cognitive deficits and negative symptoms associated with the condition.
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PMID:Effects of rivastigmine on cognitive function and quality of life in patients with schizophrenia. 1464 12

Neurologists and ophthalmologists should be familiar with the causes and treatment of visual hallucinations so that they are able to reassure patients and minimize the anguish associated with untreated visual hallucinations. Hallucinations are under-reported by patients because of the perceived psychiatric implication or because of poor insight into the unreal nature of the hallucinations. In the appropriate setting, physicians should specifically inquire about hallucinations as well as initiate medical treatment. Visual hallucinations have many etiologies and are associated with a variety of disorders. Identification of the associated disorder or cause is necessary to determine the appropriate treatment. Causes and associated disorders include ocular phenomena, migraine, seizures, visual loss (ie, release hallucinations), neurodegenerative disorders, midbrain injury, alcohol and drug effects, narcolepsy, post-traumatic stress disorder, and psychosis. Therapeutic treatment should be directed at the associated disorder or etiology. For instance, antiepileptic drugs may be appropriate for patients with irritative phenomena such as seizures and visual aura of migraine. Depending on the cause, other agents are available and include neuroleptics, cholinesterase inhibitors, and acetazolamide. Well-designed, randomized, controlled clinical trials regarding treatment of visual hallucinations associated with various disorders are lacking. Although complete resolution of visual hallucinations can be difficult, even minimal improvement may be symptomatically beneficial.
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PMID:Visual Hallucinations. 1466 72

Historically, drugs that increase central cholinergic transmission have primarily been investigated for relieving cognitive symptoms in mild-to-moderate Alzheimer's disease. These efforts have led to the somewhat unexpected findings that cholinergic therapy has a beneficial effect on selected neuropsychiatric symptoms in AD across disease stages. In Parkinson's disease with dementia and dementia with Lewy bodies, cholinergic deficits are more severe than in AD, and there is emerging evidence that cholinesterase inhibitors are efficacious in treating core symptoms of attentional disturbance and psychosis. Recent data also suggest a rational basis for cholinergic therapy in vascular dementia. The cognitive and neuropsychiatric effects of cholinergic therapy observed in AD and other dementias form the crux of an integrative model of cholinergic therapeutic efficacy that encompasses the diverse central nervous system actions of acetylcholine and its complementary interactions with central monoamine transmitters. This heuristic framework highlights the broader therapeutic potential of cholinergic therapy for symptom-based indications in other neuropsychiatric disorders.
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PMID:Cholinesterase-inhibitor therapy for dementia: novel clinical substrates and mechanisms for treatment response. 1503 99


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