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rCBF and cognitive impairment changes assessed by SPECT and ADAS-cog in late-onset Alzheimer's disease after 18 months of treatment with the cholinesterase inhibitors donepezil or galantamine. Brain Imaging Behav 2019; 13:75-86. [PMID: 29247294 DOI: 10.1007/s11682-017-9803-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Late-onset Alzheimer's disease (AD) differs substantially from early-onset AD. In this cross sectional study we investigated brain perfusion changes after 18 months of treatment with cholinesterase inhibitors (ChEIs) donepezil or galantamine. Twenty-five drug-naïve late-onset AD patients were recruited from outpatient clinics. We examined brain perfusion using single photon emission computed tomography (SPECT) and used three-dimensional stereotactic surface projection (3D-SSP) and the stereotactic extraction estimation method (SEE) level 3 to analyze classified gyrus level segments. We assessed cognitive function using the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) grouped into three subgroup domains, language, memory, and praxis. In the follow-up data, some regions were further hypoperfused, reflecting worsening of the disease, while other regions showed alleviated hypoperfusion, potentially related to the ChEIs treatment. Regional cerebral blood flow (rCBF) decreased in the parietal cortex and increased in the frontal and the limbic cortices. Increased hypoperfusion significantly correlated with ADAS-cog scores changes were seen in the superior parietal lobule, inferior parietal lobule, angular gyrus, and supramarginal gyrus of the parietal cortex. Alleviated hypoperfusion significantly related to recovery of ADAS-cog scores were seen in the rectal and paracentral lobule of the frontal cortex, and the anterior cingulate of the limbic cortex. These regions showed significant relationships with total ADAS-cog and language, memory and praxis subscales scores. The current longitudinal study indicates prominent rCBF changes and their relationships with changes in ADAS-cog scores in late-onset AD patients.
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Chao LL. Effects of Home Photobiomodulation Treatments on Cognitive and Behavioral Function, Cerebral Perfusion, and Resting-State Functional Connectivity in Patients with Dementia: A Pilot Trial. PHOTOBIOMODULATION PHOTOMEDICINE AND LASER SURGERY 2019; 37:133-141. [PMID: 31050950 DOI: 10.1089/photob.2018.4555] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Objective: To examine the effects of transcranial and intranasal photobiomodulation (PBM) therapy, administered at home, in patients with dementia. Background: This study sought to replicate and build upon a previously published case series report describing improved cognitive function in five patients with mild-to-moderate dementia after 12 weeks of transcranial and intranasal near-infrared (NIR) PBM therapy. Materials and methods: Eight participants (mean age: 79.8 ± 5.8 years old) diagnosed with dementia by their physicians were randomized to 12 weeks of usual care (UC, n = 4) or home PBM treatments (n = 4). The NIR PBM treatments were administered by a study partner at home three times per week with the Vielight Neuro Gamma device. The participants were assessed with the Alzheimer's Disease Assessment Scale-cognitive (ADAS-cog) subscale and the Neuropsychiatric Inventory (NPI) at baseline and 6 and 12 weeks, and with arterial spin-labeled perfusion magnetic resonance imaging (MRI) and resting-state functional MRI at baseline and 12 weeks. Results: At baseline, the UC and PBM groups did not differ demographically or clinically. However, after 12 weeks, there were improvements in ADAS-cog (group × time interaction: F1,6 = 16.35, p = 0.007) and NPI (group × time interaction: F1,6 = 7.52, p = 0.03), increased cerebral perfusion (group × time interaction: F1,6 = 8.46, p < 0.03), and increased connectivity between the posterior cingulate cortex and lateral parietal nodes within the default-mode network in the PBM group. Conclusions: Because PBM was well tolerated and associated with no adverse side effects, these results support the potential of PBM therapy as a viable home treatment for individuals with dementia.
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Affiliation(s)
- Linda L Chao
- 1 Center for Imaging of Neurodegenerative Diseases, San Francisco VA Medical Center, San Francisco, California.,2 Department of Radiology and Biomedical Imaging and University of California, San Francisco, San Francisco, California.,3 Department of Psychiatry, University of California, San Francisco, San Francisco, California
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3
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Harch PG, Fogarty EF. Hyperbaric oxygen therapy for Alzheimer's dementia with positron emission tomography imaging: a case report. Med Gas Res 2019; 8:181-184. [PMID: 30713673 PMCID: PMC6352566 DOI: 10.4103/2045-9912.248271] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/22/2018] [Indexed: 12/25/2022] Open
Abstract
A 58-year-old female was diagnosed with Alzheimer's dementia (AD) which was rapidly progressive in the 8 months prior to initiation of hyperbaric oxygen therapy (HBOT). 18Fluorodeoxyglucose (18FDG) positron emission tomography (PET) brain imaging demonstrated global and typical metabolic deficits in AD (posterior temporal-parietal watershed and cingulate areas). An 8-week course of HBOT reversed the patient's symptomatic decline. Repeat PET imaging demonstrated a corresponding 6.5-38% regional and global increase in brain metabolism, including increased metabolism in the typical AD diagnostic areas of the brain. Continued HBOT in conjunction with standard pharmacotherapy maintained the patient's symptomatic level of function over an ensuing 22 months. This is the first reported case of simultaneous HBOT-induced symptomatic and 18FDG PET documented improvement of brain metabolism in AD and suggests an effect on global pathology in AD.
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Affiliation(s)
- Paul G Harch
- Department of Medicine, Section of Emergency and Hyperbaric Medicine, Louisiana State University School of Medicine, New Orleans, LA, USA
| | - Edward F Fogarty
- Department of Radiology, University of North Dakota School of Medicine and Health Sciences, Bismarck, ND, USA
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4
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Nano-carrier enabled drug delivery systems for nose to brain targeting for the treatment of neurodegenerative disorders. J Drug Deliv Sci Technol 2018. [DOI: 10.1016/j.jddst.2017.09.022] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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5
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Shokouhi S, Campbell D, Brill AB, Gwirtsman HE. Longitudinal Positron Emission Tomography in Preventive Alzheimer's Disease Drug Trials, Critical Barriers from Imaging Science Perspective. Brain Pathol 2018; 26:664-71. [PMID: 27327527 PMCID: PMC5958602 DOI: 10.1111/bpa.12399] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 06/16/2016] [Indexed: 12/30/2022] Open
Abstract
Recent Alzheimer's trials have recruited cognitively normal people at risk for Alzheimer's dementia. Due to the lack of clinical symptoms in normal population, conventional clinical outcome measures are not suitable for these early trials. While several groups are developing new composite cognitive tests that could serve as potential outcome measures by detecting subtle cognitive changes in normal people, there is a need for longitudinal brain imaging techniques that can correlate with temporal changes in these new tests and provide additional objective measures of neuropathological changes in brain. Positron emission tomography (PET) is a nuclear medicine imaging procedure based on the measurement of annihilation photons after positron emission from radiolabeled molecules that allow tracking of biological processes in body, including the brain. PET is a well-established in vivo imaging modality in Alzheimer's disease diagnosis and research due to its capability of detecting abnormalities in three major hallmarks of this disease. These include (1) amyloid beta plaques; (2) neurofibrillary tau tangles and (3) decrease in neuronal activity due to loss of nerve cell connection and death. While semiquantitative PET imaging techniques are commonly used to set discrete cut-points to stratify abnormal levels of amyloid accumulation and neurodegeneration, they are suboptimal for detecting subtle longitudinal changes. In this study, we have identified and discussed four critical barriers in conventional longitudinal PET imaging that may be particularly relevant for early Alzheimer's disease studies. These include within and across subject heterogeneity of AD-affected brain regions, PET intensity normalization, neuronal compensations in early disease stages and cerebrovascular amyloid deposition.
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Affiliation(s)
- Sepideh Shokouhi
- Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center
| | - Desmond Campbell
- Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center
| | - Aaron B Brill
- Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center
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6
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Scheltens NME, Kuyper IS, Boellaard R, Barkhof F, Teunissen CE, Broersen LM, Lansbergen MM, van der Flier WM, van Berckel BNM, Scheltens P. Design of the NL-ENIGMA study: Exploring the effect of Souvenaid on cerebral glucose metabolism in early Alzheimer's disease. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2017; 2:233-240. [PMID: 29067310 PMCID: PMC5651347 DOI: 10.1016/j.trci.2016.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Introduction Alzheimer's disease is associated with early synaptic loss. Specific nutrients are known to be rate limiting for synapse formation. Studies have shown that administering specific nutrients may improve memory function, possibly by increasing synapse formation. This Dutch study explores the Effect of a specific Nutritional Intervention on cerebral Glucose Metabolism in early Alzheimer's disease (NL-ENIGMA, Dutch Trial Register NTR4718, http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=4718). The NL-ENIGMA study is designed to test whether the specific multinutrient combination Fortasyn Connect present in the medical food Souvenaid influences cerebral glucose metabolism as a marker for improved synapse function. Methods This study is a double-blind, randomized controlled parallel-group single-center trial. Forty drug-naive patients with mild cognitive impairment or mild dementia with evidence of amyloid deposition are 1:1 randomized to receive either the multinutrient combination or placebo once daily. Main exploratory outcome parameters include absolute quantitative positron emission tomography with 18F-fluorodeoxyglucose (including arterial sampling) and standard uptake value ratios normalized for the cerebellum or pons after 24 weeks. Discussion We expect the NL-ENIGMA study to provide further insight in the potential of this multinutrient combination to improve synapse function. This study explores the Effect of a specific Nutritional Intervention on cerebral Glucose Metabolism in early Alzheimer's disease (AD). Forty drug-naive patients with mild cognitive impairment or mild dementia because of AD will be analyzed. Synapse function is explored using positron emission tomography with 18F-fluorodeoxyglucose including arterial sampling.
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Affiliation(s)
- Nienke M E Scheltens
- Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Ingrid S Kuyper
- Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Ronald Boellaard
- Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.,Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Frederik Barkhof
- Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.,Institutes of Neurology and Healthcare Engineering, UCL, London, UK
| | - Charlotte E Teunissen
- Neurochemistry Laboratory and Biobank, Department of Clinical Chemistry, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Laus M Broersen
- Nutricia Research, Nutricia Advanced Medical Nutrition, Utrecht, The Netherlands
| | - Marieke M Lansbergen
- Nutricia Research, Nutricia Advanced Medical Nutrition, Utrecht, The Netherlands
| | - Wiesje M van der Flier
- Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.,Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands
| | - Bart N M van Berckel
- Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Philip Scheltens
- Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
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Deleye S, Waldron AM, Verhaeghe J, Bottelbergs A, Wyffels L, Van Broeck B, Langlois X, Schmidt M, Stroobants S, Staelens S. Evaluation of Small-Animal PET Outcome Measures to Detect Disease Modification Induced by BACE Inhibition in a Transgenic Mouse Model of Alzheimer Disease. J Nucl Med 2017; 58:1977-1983. [PMID: 28611242 DOI: 10.2967/jnumed.116.187625] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/31/2017] [Indexed: 01/08/2023] Open
Abstract
In this study, we investigated the effects of chronic administration of an inhibitor of the β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) on Alzheimer-related pathology by multitracer PET imaging in transgenic APPPS1-21 (TG) mice. Methods: Wild-type (WT) and TG mice received vehicle or BACE inhibitor (60 mg/kg) starting at 7 wk of age. Outcome measures of brain metabolism, neuroinflammation, and amyloid-β pathology were obtained through small-animal PET imaging with 18F-FDG, 18F-peripheral benzodiazepine receptor (18F-PBR), and 18F-florbetapir (18F-AV45), respectively. Baseline scans were acquired at 6-7 wk of age and follow-up scans at 4, 7, and 12 mo. 18F-AV45 uptake was measured at 8 and 13 mo of age. After the final scans, histologic measures of amyloid-β (4G8), microglia (ionized calcium binding adaptor molecule 1), astrocytes (glial fibrillary acidic protein), and neuronal nuclei were performed. Results: TG mice demonstrated significant age-associated increases in 18F-AV45 uptake. An effect of treatment was observed in the cortex (P = 0.0014), hippocampus (P = 0.0005), and thalamus (P < 0.0001). Histology confirmed reduction of amyloid-β pathology in TG-BACE mice. Regardless of treatment, TG mice demonstrated significantly lower 18F-FDG uptake than WT mice in the thalamus (P = 0.0004) and hippocampus (P = 0.0332). Neuronal nucleus staining was lower in both TG groups in the thalamus and cortex. 18F-PBR111 detected a significant age-related increase in TG mice (P < 0.0001) but did not detect the treatment-induced reduction in activated microglia as demonstrated by histology. Conclusion: Although 18F-FDG, 18F-PBR111, and 18F-AV45 all detected pathologic alterations between TG and WT mice, only 18F-AV45 could detect an effect of BACE inhibitor treatment. However, changes in WT binding of 18F-AV45 undermine the specificity of this effect.
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Affiliation(s)
- Steven Deleye
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Ann-Marie Waldron
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | | | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium.,Nuclear Medicine Department, University Hospital Antwerp, Antwerp, Belgium; and
| | | | - Xavier Langlois
- Foundational Neuroscience Center, Abbvie, Cambridge, Massachusetts
| | - Mark Schmidt
- Neuroscience Department, Janssen Pharmaceutica NV, Beerse, Belgium
| | - Sigrid Stroobants
- Nuclear Medicine Department, University Hospital Antwerp, Antwerp, Belgium; and
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
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8
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Nanotechnology-based drug delivery systems for Alzheimer's disease management: Technical, industrial, and clinical challenges. J Control Release 2016; 245:95-107. [PMID: 27889394 DOI: 10.1016/j.jconrel.2016.11.025] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 11/14/2016] [Accepted: 11/21/2016] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease with high prevalence in the rapidly growing elderly population in the developing world. The currently FDA approved drugs for the management of symptomatology of AD are marketed mainly as conventional oral medications. Due to their gastrointestinal side effects and lack of brain targeting, these drugs and dosage regiments hinder patient compliance and lead to treatment discontinuation. Nanotechnology-based drug delivery systems (NTDDS) administered by different routes can be considered as promising tools to improve patient compliance and achieve better therapeutic outcomes. Despite extensive research, literature screening revealed that clinical activities involving NTDDS application in research for AD are lagging compared to NTDDS for other diseases such as cancers. The industrial perspectives, processability, and cost/benefit ratio of using NTDDS for AD treatment are usually overlooked. Moreover, active and passive immunization against AD are by far the mostly studied alternative AD therapies because conventional oral drug therapy is not yielding satisfactorily results. NTDDS of approved drugs appear promising to transform this research from 'paper to clinic' and raise hope for AD sufferers and their caretakers. This review summarizes the recent studies conducted on NTDDS for AD treatment, with a primary focus on the industrial perspectives and processability. Additionally, it highlights the ongoing clinical trials for AD management.
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Safavi M, Sabourian R, Abdollahi M. The development of biomarkers to reduce attrition rate in drug discovery focused on oncology and central nervous system. Expert Opin Drug Discov 2016; 11:939-56. [DOI: 10.1080/17460441.2016.1217196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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10
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Miettinen PS, Jauhiainen AM, Tarkka IM, Pihlajamäki M, Gröhn H, Niskanen E, Hänninen T, Vanninen R, Soininen H. Long-Term Response to Cholinesterase Inhibitor Treatment Is Related to Functional MRI Response in Alzheimer's Disease. Dement Geriatr Cogn Disord 2016; 40:243-55. [PMID: 26305064 DOI: 10.1159/000435948] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/12/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Treatment of Alzheimer's disease (AD) with cholinesterase inhibitors (ChEI) enhances cholinergic activity and alleviates clinical symptoms. However, there is variation in the clinical response as well as system level changes revealed by functional MRI (fMRI) studies. METHODS We investigated 18 newly diagnosed mild AD patients with fMRI using a face recognition task after a single oral dose of rivastigmine, a single dose of placebo and 1-month treatment with rivastigmine. The clinical follow-up took place at 6 and 12 months. RESULTS MMSE score difference between baseline and the follow-ups showed a positive correlation with fMRI activation difference between treatment and placebo in the right prefrontal cortex. A negative correlation was found for the left prefrontal cortex and the left fusiform gyrus. In addition, greater signal intensity in the right versus the left fusiform gyrus predicted a response to ChEI with increasing MMSE scores during the follow-up with 77.8% sensitivity and 77.8% specificity. CONCLUSIONS The increased fMRI activation by cholinergic stimulation in brain areas associated with the processing of the visual task reveals still functioning brain networks and a subsequent positive effect of ChEI on cognition. Thus, fMRI may be useful for identifying AD patients most likely to respond to treatment with ChEI.
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Affiliation(s)
- Pekka S Miettinen
- Department of Neurology, University of Eastern Finland, Kuopio, Finland
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11
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Grothe MJ, Heinsen H, Amaro E, Grinberg LT, Teipel SJ. Cognitive Correlates of Basal Forebrain Atrophy and Associated Cortical Hypometabolism in Mild Cognitive Impairment. Cereb Cortex 2015; 26:2411-2426. [PMID: 25840425 DOI: 10.1093/cercor/bhv062] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Degeneration of basal forebrain (BF) cholinergic nuclei is associated with cognitive decline, and this effect is believed to be mediated by neuronal dysfunction in the denervated cortical areas. MRI-based measurements of BF atrophy are increasingly being used as in vivo surrogate markers for cholinergic degeneration, but the functional implications of reductions in BF volume are not well understood. We used high-resolution MRI, fluorodeoxyglucose-positron emission tomography (PET), and neuropsychological test data of 132 subjects with mild cognitive impairment (MCI) and 177 cognitively normal controls to determine associations between BF atrophy, cortical hypometabolism, and cognitive deficits. BF atrophy in MCI correlated with both impaired memory function and attentional control deficits, whereas hippocampus volume was more specifically associated with memory deficits. BF atrophy was also associated with widespread cortical hypometabolism, and path analytic models indicated that hypometabolism in domain-specific cortical networks mediated the association between BF volume and cognitive dysfunction. The presence of cortical amyloid pathology, as assessed using AV45-PET, did not significantly interact with the observed associations. These data underline the potential of multimodal imaging markers to study structure-function-cognition relationships in the living human brain and provide important in vivo evidence for an involvement of the human BF in cortical activity and cognitive function.
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Affiliation(s)
- Michel J Grothe
- German Center for Neurodegenerative Diseases (DZNE), Rostock, Germany
| | - Helmut Heinsen
- Laboratory of Morphological Brain Research, Department of Psychiatry, University of Würzburg, Würzburg, Germany
| | | | - Lea T Grinberg
- Aging Brain Study Group, LIM-22, Department of Pathology, University of Sao Paulo Medical School, Sao Paulo, Brazil.,UCSF Memory and Aging Center, University of California - San Francisco, San Francisco, CA, USA
| | - Stefan J Teipel
- German Center for Neurodegenerative Diseases (DZNE), Rostock, Germany.,Department of Psychosomatic Medicine, University of Rostock, Rostock, Germany
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Dehabadi MH, Davis BM, Wong TK, Cordeiro MF. Retinal manifestations of Alzheimer's disease. Neurodegener Dis Manag 2015; 4:241-52. [PMID: 25095818 DOI: 10.2217/nmt.14.19] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is neurodegenerative condition and most common cause of dementia worldwide. Current criteria for its diagnosis and monitoring rely on subjective, expensive or invasive methods that lack sufficient sensitivity, such that a concrete diagnosis of AD can only be made postmortem. Given the structural similarities of the neuro-retina and central nervous system, researchers have shown many manifestations of AD to be detectible in the retinae of humans and transgenic models of AD. Due to the eye's unique optical properties allowing noninvasive in vivo imaging, the retina could provide a window for the early diagnosis and monitoring of AD long before symptom manifestation.
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Affiliation(s)
- Mohammad H Dehabadi
- Glaucoma & Retinal Neurodegeneration Research Group, Visual Neuroscience, UCL Institute of Ophthalmology, London, UK
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Shimizu S, Kanetaka H, Hirose D, Sakurai H, Hanyu H. Differential effects of acetylcholinesterase inhibitors on clinical responses and cerebral blood flow changes in patients with Alzheimer's disease: a 12-month, randomized, and open-label trial. Dement Geriatr Cogn Dis Extra 2015; 5:135-46. [PMID: 25999980 PMCID: PMC4439833 DOI: 10.1159/000375527] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS The present study evaluated the differences in treatment outcomes and brain perfusion changes among 3 types of acetylcholinesterase inhibitors (AchEIs, i.e. donepezil, rivastigmine, and galantamine). METHODS This was a prospective, longitudinal, randomized, open-label, 3-arm (donepezil, rivastigmine, or galantamine), parallel-group, 12-month clinical trial carried out in 55 patients with AD. RESULTS At 6 months, the results of the Mini-Mental State Examination (MMSE) and the Trail Making Test (TMT)-Part A showed an improvement versus baseline in the donepezil treatment group. All groups showed a significant increase in regional cerebral blood flow (rCBF), mainly in the frontal lobe. Significant rCBF reduction was observed in the temporal lobe and cingulate gyrus in all 3 groups. CONCLUSION AchEI treatment prevents the progression of cognitive impairment and increases the relative rCBF in the frontal lobe.
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Affiliation(s)
- Soichiro Shimizu
- Department of Geriatric Medicine, Tokyo Medical University, Tokyo, Japan
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Ahnaou A, Huysmans H, Jacobs T, Drinkenburg W. Cortical EEG oscillations and network connectivity as efficacy indices for assessing drugs with cognition enhancing potential. Neuropharmacology 2014; 86:362-77. [DOI: 10.1016/j.neuropharm.2014.08.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 08/18/2014] [Accepted: 08/20/2014] [Indexed: 10/24/2022]
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Relkin NR. Beyond symptomatic therapy: a re-examination of acetylcholinesterase inhibitors in Alzheimer’s disease. Expert Rev Neurother 2014; 7:735-48. [PMID: 17561789 DOI: 10.1586/14737175.7.6.735] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Acetylcholinesterase inhibitors (AChEIs) are generally regarded as palliative treatments for Alzheimer's disease that slow the progression of dementia symptoms without altering Alzheimer's disease's underlying pathogenic mechanisms. This concept is based on inference rather than evidence, and has limited the scope and persistence of AChEI use in clinical practice. Recent preclinical studies demonstrate that AChEIs exhibit a number of biological effects in addition to cholinesterase inhibition. A broader understanding of the possible mechanisms of action of AChEIs in Alzheimer's disease could result in more effective use and assist in the development of new and improved therapies. The available evidence brings into question the prevailing view that AChEIs are exclusively symptomatic treatments and supports the use of these agents persistently throughout the course of Alzheimer's disease.
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Affiliation(s)
- Norman R Relkin
- Joan and Sanford I. Weill Medical College of Cornell University, 428 East 72nd Street, Suite 500, NY 10017, USA.
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17
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Nordberg A, Ballard C, Bullock R, Darreh-Shori T, Somogyi M. A review of butyrylcholinesterase as a therapeutic target in the treatment of Alzheimer's disease. Prim Care Companion CNS Disord 2013; 15:PCC.12r01412. [PMID: 23930233 PMCID: PMC3733526 DOI: 10.4088/pcc.12r01412] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 10/11/2012] [Indexed: 01/20/2023] Open
Abstract
OBJECTIVE To examine the role of butyrylcholinesterase (BuChE) in cholinergic signaling and neurologic conditions, such as Alzheimer's disease (AD). The rationale for inhibiting cholinesterases in the management of AD, including clinical evidence supporting use of the dual acetylcholinesterase (AChE) and BuChE inhibitor rivastigmine, is discussed. DATA SOURCES PubMed searches were performed using butyrylcholinesterase as a keyword. English-language articles referenced in PubMed as of September 2011 were included. Study Selection and Data Synthesis: English-language articles related to BuChE considered to be of clinical relevance to physicians were included. English-language articles specifically related to AChE were not included, as the role of AChE in cholinergic signaling and the underlying pathology of AD is well documented. Reference lists of included publications were used to supplement the search. RESULTS AChE and BuChE play a role in cholinergic signaling; BuChE can hydrolyze acetylcholine and compensate for AChE when levels are depleted. In the AD brain, AChE levels decrease, while BuChE levels are reportedly increased or unchanged, with changes becoming more pronounced during the disease course. Furthermore, BuChE genotype may influence AD risk and rate of disease progression. Strategies that increase acetylcholine levels (eg, cholinesterase inhibitors) demonstrate symptomatic efficacy in AD. Rivastigmine has proven cognitive efficacy in clinical trials, and data suggest that its action is mediated, in part, by inhibition of BuChE. Retrospective analyses of clinical trials provide evidence that BuChE genotype may also influence treatment response. CONCLUSIONS AChE-selective inhibitors and a dual AChE and BuChE inhibitor demonstrate symptomatic efficacy in AD. Mounting preclinical and clinical evidence for a role of BuChE in maintaining normal cholinergic function and the pathology of AD provides a rationale for further studies investigating use of rivastigmine in AD and the influence of BuChE genotype on observed efficacy.
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Affiliation(s)
- Agneta Nordberg
- Alzheimer Neurobiology Center, Karolinska Institute, Stockholm, Sweden (Drs Nordberg and Darreh-Shori); Wolfson Centre for Age-Related Diseases, King's College, London, United Kingdom (Dr Ballard); Kingshill Research Centre, Victoria Hospital, Swindon, United Kingdom (Dr Bullock); and Novartis Pharmaceuticals Corporation, East Hanover, New Jersey (Dr Somogyi)
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Ismail MF, Elmeshad AN, Salem NAH. Potential therapeutic effect of nanobased formulation of rivastigmine on rat model of Alzheimer's disease. Int J Nanomedicine 2013; 8:393-406. [PMID: 23378761 PMCID: PMC3558309 DOI: 10.2147/ijn.s39232] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Background To sustain the effect of rivastigmine, a hydrophilic cholinesterase inhibitor, nanobased formulations were prepared. The efficacy of the prepared rivastigmine liposomes (RLs) in comparison to rivastigmine solution (RS) was assessed in an aluminium chloride (AlCl3)-induced Alzheimer’s model. Methods Liposomes were prepared by lipid hydration (F1) and heating (F2) methods. Rats were treated with either RS or RLs (1 mg/kg/day) concomitantly with AlCl3 (50 mg/kg/day). Results The study showed that the F1 method produced smaller liposomes (67.51 ± 14.2 nm) than F2 (528.7 ± 15.5 nm), but both entrapped the same amount of the drug (92.1% ± 1.4%). After 6 hours, 74.2% ± 1.5% and 60.8% ± 2.3% of rivastigmine were released from F1 and F2, respectively. Both RLs and RS improved the deterioration of spatial memory induced by AlCl3, with RLs having a superior effect. Further biochemical measurements proved that RS and RLs were able to lower plasma C-reactive protein, homocysteine and asymmetric dimethy-larginine levels. RS significantly attenuated acetylcholinesterase (AChE) activity, whereas Na+/K+-adenosine triphosphatase (ATPase) activity was enhanced compared to the AlCl3-treated animals; however, RLs succeeded in normalization of AChE and Na+/K+ ATPase activities. Gene-expression profile showed that cotreatment with RS to AlCl3-treated rats succeeded in exerting significant decreases in BACE1, AChE, and IL1B gene expression. Normalization of the expression of the aforementioned genes was achieved by coadministration of RLs to AlCl3-treated rats. The profound therapeutic effect of RLs over RS was evidenced by nearly preventing amyloid plaque formation, as shown in the histopathological examination of rat brain. Conclusion RLs could be a potential drug-delivery system for ameliorating Alzheimer’s disease.
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Herholz K. Use of FDG PET as an imaging biomarker in clinical trials of Alzheimer’s disease. Biomark Med 2012; 6:431-9. [DOI: 10.2217/bmm.12.51] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
PET with the glucose analog FDG as a tracer is a mature and increasingly available clinical imaging technique that can improve the diagnostic accuracy for Alzheimer’s disease, which is of particular value at an early stage of the disease when clinical symptoms are still mild and nonspecific. It can also monitor progression of Alzheimer’s disease, and the findings are closely related to clinical symptoms. FDG PET, therefore, could also potentially be used as an imaging biomarker for selection of patients and assessment of outcome in clinical trials. Several published intervention studies indicate a good correspondence between clinical outcome and FDG PET findings, but study designs and methods used for data analysis vary widely. Recent developments towards standardization of largely user-independent methods for quantification of regional metabolic impairment on FDG PET scans will allow a new generation of studies that could provide the required evidence for full qualification of FDG PET as an imaging biomarker in clinical trials.
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Affiliation(s)
- Karl Herholz
- The University of Manchester, Wolfson Molecular Imaging Centre, 27 Palatine Road, Manchester, M20 3LJ, UK
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Di Carlo M, Giacomazza D, San Biagio PL. Alzheimer's disease: biological aspects, therapeutic perspectives and diagnostic tools. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:244102. [PMID: 22595372 DOI: 10.1088/0953-8984/24/24/244102] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Alzheimer's disease (AD) is the most common form of dementia among older people. Dementia is an irreversible brain disorder that seriously affects a person's ability to carry out daily activities. It is characterized by loss of cognitive functioning and behavioral abilities, to such an extent that it interferes with the daily life and activities of the affected patients. Although it is still unknown how the disease process begins, it seems that brain damage starts a decade or more before problems become evident. Scientific data seem to indicate that changes in the generation or the degradation of the amyloid-b peptide (Aβ) lead to the formation of aggregated structures that are the triggering molecular events in the pathogenic cascade of AD. This review summarizes some characteristic features of Aβ misfolding and aggregation and how cell damage and death mechanisms are induced by these supramolecular and toxic structures. Further, some interventions for the early diagnosis of AD are described and in the last part the potential therapeutic strategies adoptable to slow down, or better block, the progression of the pathology are reported.
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Affiliation(s)
- M Di Carlo
- Istituto di Biomedicina ed Immunologia Molecolare (IBIM), CNR, Palermo, Italy.
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Koronyo Y, Salumbides BC, Black KL, Koronyo-Hamaoui M. Alzheimer's disease in the retina: imaging retinal aβ plaques for early diagnosis and therapy assessment. NEURODEGENER DIS 2012; 10:285-93. [PMID: 22343730 DOI: 10.1159/000335154] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 11/16/2011] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Definite Alzheimer's disease (AD) diagnosis at early stages is vital for targeting intervention, yet currently unavailable. Noninvasive detection of the pathological hallmark, amyloid-β protein (Aβ) plaques, is limited in the brain. However, the existence of Aβ plaques in the retina, possibly at presymptomatic stages, may improve early detection of AD. OBJECTIVE To summarize clinical and preclinical evidence showing that the retina, an accessible part of the central nervous system, displays abnormalities in AD, especially Aβ plaque pathology. The ability to monitor in vivo retinal plaque dynamics in response to immunotherapy is also assessed. METHODS Literature analysis of retinal AD pathology and imaging is provided. In our studies, systemic curcumin is administered to enable monitoring of retinal Aβ plaques in live APP(SWE)/PS1(Δ)(E9) transgenic mice by optical imaging. RESULTS Visual and retinal abnormalities, including early manifestation of retinal Aβ plaque pathology, have been documented in AD patients and animal models. In mouse models, retinal Aβ plaques accumulate with age and decrease in response to immunotherapy, consistent with brain pathology. Here, we demonstrate that retinal plaques can be individually monitored in real time following glatiramer acetate immunization. CONCLUSION Translation of noninvasive retinal-plaque imaging to humans could eventually facilitate early and accurate AD diagnosis and therapy assessment.
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Affiliation(s)
- Yosef Koronyo
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Los Angeles, Calif, USA
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Abstract
Neuroimaging allows researchers and clinicians to noninvasively assess structure and function of the brain. With the advances of imaging modalities such as magnetic resonance, nuclear, and optical imaging; the design of target-specific probes; and/or the introduction of reporter gene assays, these technologies are now capable of visualizing cellular and molecular processes in vivo. Undoubtedly, the system biological character of molecular neuroimaging, which allows for the study of molecular events in the intact organism, will enhance our understanding of physiology and pathophysiology of the brain and improve our ability to diagnose and treat diseases more specifically. Technical/scientific challenges to be faced are the development of highly sensitive imaging modalities, the design of specific imaging probe molecules capable of penetrating the CNS and reporting on endogenous cellular and molecular processes, and the development of tools for extracting quantitative, biologically relevant information from imaging data. Today, molecular neuroimaging is still an experimental approach with limited clinical impact; this is expected to change within the next decade. This article provides an overview of molecular neuroimaging approaches with a focus on rodent studies documenting the exploratory state of the field. Concepts are illustrated by discussing applications related to the pathophysiology of Alzheimer's disease.
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Affiliation(s)
- Jan Klohs
- Institute for Biomedical Engineering, ETH & University of Zürich, Switzerland
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Bailey JA, Ray B, Greig NH, Lahiri DK. Rivastigmine lowers Aβ and increases sAPPα levels, which parallel elevated synaptic markers and metabolic activity in degenerating primary rat neurons. PLoS One 2011; 6:e21954. [PMID: 21799757 PMCID: PMC3142110 DOI: 10.1371/journal.pone.0021954] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 06/15/2011] [Indexed: 01/20/2023] Open
Abstract
Overproduction of amyloid-β (Aβ) protein in the brain has been hypothesized as the primary toxic insult that, via numerous mechanisms, produces cognitive deficits in Alzheimer's disease (AD). Cholinesterase inhibition is a primary strategy for treatment of AD, and specific compounds of this class have previously been demonstrated to influence Aβ precursor protein (APP) processing and Aβ production. However, little information is available on the effects of rivastigmine, a dual acetylcholinesterase and butyrylcholinesterase inhibitor, on APP processing. As this drug is currently used to treat AD, characterization of its various activities is important to optimize its clinical utility. We have previously shown that rivastigmine can preserve or enhance neuronal and synaptic terminal markers in degenerating primary embryonic cerebrocortical cultures. Given previous reports on the effects of APP and Aβ on synapses, regulation of APP processing represents a plausible mechanism for the synaptic effects of rivastigmine. To test this hypothesis, we treated degenerating primary cultures with rivastigmine and measured secreted APP (sAPP) and Aβ. Rivastigmine treatment increased metabolic activity in these cultured cells, and elevated APP secretion. Analysis of the two major forms of APP secreted by these cultures, attributed to neurons or glia based on molecular weight showed that rivastigmine treatment significantly increased neuronal relative to glial secreted APP. Furthermore, rivastigmine treatment increased α-secretase cleaved sAPPα and decreased Aβ secretion, suggesting a therapeutic mechanism wherein rivastigmine alters the relative activities of the secretase pathways. Assessment of sAPP levels in rodent CSF following once daily rivastigmine administration for 21 days confirmed that elevated levels of APP in cell culture translated in vivo. Taken together, rivastigmine treatment enhances neuronal sAPP and shifts APP processing toward the α-secretase pathway in degenerating neuronal cultures, which mirrors the trend of synaptic proteins, and metabolic activity.
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Affiliation(s)
- Jason A. Bailey
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Balmiki Ray
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Nigel H. Greig
- Laboratory of Neuroscience, Intramural Research Program, National Institute of Aging, National Institutes of Health, Baltimore Maryland, United States of America
| | - Debomoy K. Lahiri
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
- * E-mail:
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Kadir A, Nordberg A. Target-specific PET probes for neurodegenerative disorders related to dementia. J Nucl Med 2010; 51:1418-30. [PMID: 20810758 DOI: 10.2967/jnumed.110.077164] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Dementia is a highly prevalent problem causing considerable disability and mortality and exacting great costs to individuals, their families, and society. The 4 most common neurodegenerative disorders that cause dementia-Alzheimer disease, frontotemporal dementia, dementia with Lewy bodies, and dementia in Parkinson disease-have different underlying etiologies and pathogenetic mechanisms. There is a great need for early diagnostic markers; functional brain imaging may therefore assist in the detection and differential diagnosis of dementia due to neurodegenerative diseases. Functional imaging such as PET allows in vivo imaging of functional brain activity indicating cerebral blood flow and cerebral glucose metabolism, and PET allows imaging of neurotransmitter activity, including that of the cholinergic, dopaminergic, and serotonergic systems. New PET neuroimaging tracers are being developed for detecting pathologic parameters such as amyloid plaque and microglial activity. The development of molecular imaging is important for early diagnosis of dementia, selection of patients for therapies, and evaluation of therapies.
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Affiliation(s)
- Ahmadul Kadir
- Division of Alzheimer Neurobiology, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
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Laxton AW, Tang-Wai DF, McAndrews MP, Zumsteg D, Wennberg R, Keren R, Wherrett J, Naglie G, Hamani C, Smith GS, Lozano AM. A phase I trial of deep brain stimulation of memory circuits in Alzheimer's disease. Ann Neurol 2010; 68:521-34. [PMID: 20687206 DOI: 10.1002/ana.22089] [Citation(s) in RCA: 487] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Adrian W Laxton
- Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada
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Hampel H, Frank R, Broich K, Teipel SJ, Katz RG, Hardy J, Herholz K, Bokde ALW, Jessen F, Hoessler YC, Sanhai WR, Zetterberg H, Woodcock J, Blennow K. Biomarkers for Alzheimer's disease: academic, industry and regulatory perspectives. Nat Rev Drug Discov 2010; 9:560-74. [PMID: 20592748 DOI: 10.1038/nrd3115] [Citation(s) in RCA: 472] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Advances in therapeutic strategies for Alzheimer's disease that lead to even small delays in onset and progression of the condition would significantly reduce the global burden of the disease. To effectively test compounds for Alzheimer's disease and bring therapy to individuals as early as possible there is an urgent need for collaboration between academic institutions, industry and regulatory organizations for the establishment of standards and networks for the identification and qualification of biological marker candidates. Biomarkers are needed to monitor drug safety, to identify individuals who are most likely to respond to specific treatments, to stratify presymptomatic patients and to quantify the benefits of treatments. Biomarkers that achieve these characteristics should enable objective business decisions in portfolio management and facilitate regulatory approval of new therapies.
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Affiliation(s)
- Harald Hampel
- Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Johann Wolfgang Goethe-University, Heinrich-Hoffmann-Str. 10, 60528 Frankfurt/Main, Germany.
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Abstract
OBJECTIVES Cortical systems involved in the response to medication treatment for Alzheimer's disease (AD) are poorly understood. Preclinical studies have demonstrated the effect of memantine on neuroreceptors and cell physiology, although the impact of treatment on cortical activity in vivo is not known. DESIGN F-fluorodeoxyglucose positron emission tomography (PET) imaging and clinical assessment before and after open-label memantine treatment. PARTICIPANTS/SETTING Seventeen outpatients with probable AD on stable cholinesterase inhibitor medication. INTERVENTION Memantine up to 10 mg twice daily for 10 weeks. MEASUREMENTS Voxel-based analyses of change in cortical metabolic activity; Mattis Dementia Rating Scale (DRS), and Neurobehavioral Rating Scale (NRS). RESULTS : Mean age was 81 years; mean Mini-Mental State Examination score was 19.4. Compared with baseline, metabolic activity was significantly higher after 10 weeks memantine treatment in two cortical regions bilaterally: the inferior temporal gyrus (BA 20) and the angular gyrus/supramarginal gyrus (BA 39, 40). There was no significant relationship between change in DRS score and change in cortical metabolism, although change in NRS score was associated with the extent of metabolic change in the right parietal and temporal cortex. CONCLUSION Metabolic activity in bilateral inferior parietal and temporal cortex increases during 10 weeks of memantine treatment in patients with AD. PET imaging can reveal functional effects of medications on neural activity and may help to define critical mechanisms involved in drug treatment.
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Abstract
In Alzheimer disease (AD), which is the most common cause of dementia, the underlying disease pathology most probably precedes the onset of cognitive symptoms by many years. Thus, efforts are underway to find early diagnostic markers as well as disease-modifying treatments for this disorder. PET enables various brain systems to be monitored in living individuals. In patients with AD, PET can be used to investigate changes in cerebral glucose metabolism, various neurotransmitter systems, neuroinflammation, and the protein aggregates that are characteristic of the disease, notably the amyloid deposits. These investigations are helping to further our understanding of the complex pathophysiological mechanisms that underlie AD, as well as aiding the early and differential diagnosis of the disease in the clinic. In the future, PET studies will also be useful for identifying new therapeutic targets and monitoring treatment outcomes. Amyloid imaging could be useful as early diagnostic marker of AD and for selecting patients for anti-amyloid-beta therapy, while cerebral glucose metabolism could be a suitable PET marker for monitoring disease progression. For the near future, multitracer PET studies are unlikely to be used routinely in the clinic for AD, being both burdensome and expensive; however, such studies are very informative in a research context.
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Affiliation(s)
- Agneta Nordberg
- Division of Alzheimer Neurobiology, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Karolinska University Hospital Huddinge, Novum, Stockholm, Sweden.
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Asai M, Fujikawa A, Noda A, Miyoshi S, Matsuoka N, Nishimura S. Donepezil- and scopolamine-induced rCMRglu changes assessed by PET in conscious rhesus monkeys. Ann Nucl Med 2009; 23:877-82. [PMID: 19924379 DOI: 10.1007/s12149-009-0316-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 10/19/2009] [Indexed: 11/26/2022]
Abstract
OBJECTIVE [(18)F]Fluoro-2-deoxyglucose positron emission tomography (FDG-PET) is a useful tool for measuring the regional cerebral metabolic rate of glucose (rCMRglu), which is an index of neuronal activity. Donepezil, an acetylcholine esterase inhibitor (AChEI), has been recommended as a treatment option for patients with Alzheimer's disease (AD). We aimed to characterize the effects of donepezil on rCMRglu using FDG-PET in non-human primates. METHODS We investigated the effects of administration of donepezil (500 microg/kg, i.m.), the non-selective muscarinic ACh receptor antagonist scopolamine (30 microg/kg, i.m.), and the coadministration of both drugs on the rCMRglu of conscious young rhesus monkeys. RESULTS Donepezil increased the rCMRglu in all regions of interest except in the thalamus. Scopolamine treatment also increased the rCMRglu in all regions of interest except the cerebellum and thalamus. However, these effects disappeared with coadministration of the drugs. CONCLUSIONS This PET study showed that administration of donepezil or scopolamine alone increased the rCMRglu in conscious rhesus monkeys. We also found that the donepezil-induced increase was abolished by simultaneous administration of scopolamine, suggesting that muscarinic ACh receptor function plays an important role in the effect of donepezil.
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Affiliation(s)
- Makoto Asai
- The Medical and Pharmacological Research Center Foundation, Hakui, Ishikawa, Japan.
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Peters F, Collette F, Degueldre C, Sterpenich V, Majerus S, Salmon E. The neural correlates of verbal short-term memory in Alzheimer's disease: an fMRI study. Brain 2009; 132:1833-46. [PMID: 19433442 DOI: 10.1093/brain/awp075] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although many studies have shown diminished performance in verbal short-term memory tasks in Alzheimer's disease, few studies have explored the neural correlates of impaired verbal short-term memory in Alzheimer's disease patients. In this fMRI study, we examined alterations in brain activation patterns during a verbal short-term memory recognition task, by differentiating encoding and retrieval phases. Sixteen mild Alzheimer's disease patients and 16 elderly controls were presented with lists of four words followed, after a few seconds, by a probe word. Participants had to judge whether the probe matched one of the items of the memory list. In both groups, the short-term memory task elicited a distributed fronto-parieto-temporal activation that encompassed bilateral inferior frontal, insular, supplementary motor, precentral and postcentral areas, consistent with previous studies of verbal short-term memory in young subjects. Most notably, Alzheimer's disease patients showed reduced activation in several regions during the encoding phase, including the bilateral middle frontal and the left inferior frontal gyri (associated with executive control processes) as well as the transverse temporal gyri (associated with phonological processing). During the recognition phase, we found decreased activation in the left supramarginal gyrus and the right middle frontal gyrus in Alzheimer's disease patients compared with healthy seniors, possibly related to deficits in manipulation and decision processes for phonological information. At the same time, Alzheimer's disease patients showed increased activation in several brain areas, including the left parahippocampus and hippocampus, suggesting that Alzheimer's disease patients may recruit alternative recognition mechanisms when performing a short-term memory task. Overall, our results indicate that Alzheimer's disease patients show differences in the functional networks underlying memory over short delays, mostly in brain areas known to support phonological processing or executive functioning.
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Affiliation(s)
- Frédéric Peters
- Cyclotron Research Centre, University of Liège, iège, Belgium
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Gispen-de Wied CC, Kritsidima M, Elferink AJA. The validity of biomarkers as surrogate endpoints in Alzheimer's disease by means of the Quantitative Surrogate Validation Level of Evidence Scheme (QSVLES). J Nutr Health Aging 2009; 13:376-87. [PMID: 19300886 DOI: 10.1007/s12603-009-0049-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To evaluate the validity of biomarkers that are currently being proposed as potential surrogate endpoints in AD clinical trials with the aid of the "Quantitative Surrogate Validation Level of Evidence Schema" (QSVLES) proposed by Lassere et.al. (1). PROCEDURE A Pubmed literature search was conducted to identify AD biomarkers with SEP potential, and the QSVLES was applied to determine the extent of the SEP validity. RESULTS MRI, PET and MRS measures attained a total validity score of 4, NAA/Cre a total score of 5, and cerebral blood flow (SPECT), Abeta , Tau and APP a total score of 2. None of these biomarkers could fall into the rank of Levels 1 or 2, reserved for SEPs, according to the QSVLES criteria. This was mainly attributed to the lack of sufficient evidence that was derived from high ranking studies (RCT, prospective observational studies). CONCLUSION Though residing on SEPs as sole determinants of the benefit/risk ratio of AD medications seems to be pretty far, there could be certain cases where the use of SEPs may be beneficial, making efficient therapies available faster when there is a major public health interest involved. However, the potential risks of relying on invalid SEPs should not be underestimated and therefore the research on SEP validation and the development of specific validation guidance should be encouraged. The QSVLES, though not devoid of criticism, may be proposed as a starting point.
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Cognitive and cerebral metabolic effects of celecoxib versus placebo in people with age-related memory loss: randomized controlled study. Am J Geriatr Psychiatry 2008; 16:999-1009. [PMID: 19038899 PMCID: PMC2693408 DOI: 10.1097/jgp.0b013e31818cd3a4] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Because anti-inflammatory drugs may delay cognitive decline and influence brain metabolism in normal aging, the authors determined the effects of the cyclooxygenase-2 inhibitor, celecoxib, on cognitive performance and regional cerebral glucose metabolism in nondemented volunteers with mild age-related memory decline. DESIGN Randomized, double-blind, placebo-controlled, parallel group trial with 18-months of exposure to study medication. SETTING University research institute. PARTICIPANTS Eighty-eight subjects, aged 40-81 years (mean: 58.7, SD: 8.9 years) with mild self-reported memory complaints but normal memory performance scores were recruited from community physician referrals, media coverage, and advertising. Forty subjects completed the study. INTERVENTIONS Daily celecoxib dose of 200 or 400 mg, or placebo. MAIN OUTCOME MEASURES Standardized neuropsychological test battery and statistical parametric mapping (SPM) of FDG-PET scans performed during mental rest. RESULTS Measures of cognition showed significant between-group differences in executive functioning (F [1, 30] = 5.06, p = 0.03) and language/semantic memory (F [1, 31] = 6.19, p = 0.02), favoring the celecoxib group compared with the placebo group. Concomitantly, FDG-PET scans demonstrated bilateral metabolic increases in prefrontal cortex in the celecoxib group in the vicinity of Brodmann's areas 9 and 10, but not in the placebo group. SPM analyses of the PET data pooled by treatment arm corresponded to a 6% increase in activity over pretreatment levels (p <0.01, after adjustment for multiple comparisons). CONCLUSIONS These results suggest that daily celecoxib use may improve cognitive performance and increase regional brain metabolism in people with age-associated memory decline.
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Lee PH, Yong SW, An YS. Changes in Cerebral Glucose Metabolism in Patients with Parkinson Disease with Dementia After Cholinesterase Inhibitor Therapy. J Nucl Med 2008; 49:2006-11. [DOI: 10.2967/jnumed.108.054668] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Sabbagh MN, Richardson S, Relkin N. Disease-modifying approaches to Alzheimer's disease: challenges and opportunities-Lessons from donepezil therapy. Alzheimers Dement 2008; 4:S109-18. [PMID: 18631986 DOI: 10.1016/j.jalz.2007.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The era of disease modification as a therapeutic option for Alzheimer's disease (AD) is upon us. With dozens of novel drugs in development, there is more need than ever to develop biomarkers that distinguish normal aging from AD and AD from other dementias, track changes over time as disease progresses, and respond to interventions. Future trials will need to weight biomarker outcomes equal to cognitive outcomes especially when the biomarkers are linked to specific mechanisms, such as changes to beta amyloid (Abeta) deposition or brain volume. Since the advent of donepezil as a treatment for AD, new mechanisms of action of this molecule have been discovered. In this perspective, we review trial design and discuss the use of biomarkers by using lessons learned from previous trials conducted with cholinergic therapy.
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Affiliation(s)
- Marwan N Sabbagh
- Cleo Roberts Center for Clinical Research, Sun Health Research Institute, Sun City, AZ, USA. Marwan.
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Gianotti LRR, Künig G, Faber PL, Lehmann D, Pascual-Marqui RD, Kochi K, Schreiter-Gasser U. Rivastigmine effects on EEG spectra and three-dimensional LORETA functional imaging in Alzheimer's disease. Psychopharmacology (Berl) 2008; 198:323-32. [PMID: 18446328 DOI: 10.1007/s00213-008-1111-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 02/09/2008] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The objective of the study is to investigate the electrocortical and the global cognitive effects of 3 months rivastigmine medication in a group of mild to moderate Alzheimer's disease patients. MATERIALS AND METHODS Multichannel EEG and cognitive performances measured with the Mini Mental State Examination in a group of 16 patients with mild to moderate Alzheimer's Disease were collected before and 3 months after the onset of rivastigmine medication. RESULTS Spectral analysis of the EEG data showed a significant power decrease in the delta and theta frequency bands during rivastigmine medication, i.e., a shift of the power spectrum towards 'normalization'. Three-dimensional low resolution electromagnetic tomography (LORETA) functional imaging localized rivastigmine effects in a network that includes left fronto-parietal regions, posterior cingulate cortex, bilateral parahippocampal regions, and the hippocampus. Moreover, a correlation analysis between differences in the cognitive performances during the two recordings and LORETA-computed intracortical activity showed, in the alpha1 frequency band, better cognitive performance with increased cortical activity in the left insula. CONCLUSION The results point to a 'normalization' of the EEG power spectrum due to medication, and the intracortical localization of these effects showed an increase of cortical activity in frontal, parietal, and temporal regions that are well-known to be affected in Alzheimer's disease. The topographic convergence of the present results with the memory network proposed by Vincent et al. (J. Neurophysiol. 96:3517-3531, 2006) leads to the speculation that in our group of patients, rivastigmine specifically activates brain regions that are involved in memory functions, notably a key symptom in this degenerative disease.
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Affiliation(s)
- Lorena R R Gianotti
- The KEY Institute for Brain-Mind Research, University Hospital of Psychiatry, University of Zurich, Lenggstrasse 31, CH-8032 Zurich, Switzerland.
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Kadir A, Andreasen N, Almkvist O, Wall A, Forsberg A, Engler H, Hagman G, Lärksäter M, Winblad B, Zetterberg H, Blennow K, Långström B, Nordberg A. Effect of phenserine treatment on brain functional activity and amyloid in Alzheimer's disease. Ann Neurol 2008; 63:621-31. [DOI: 10.1002/ana.21345] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Small GW, Bookheimer SY, Thompson PM, Cole GM, Huang SC, Kepe V, Barrio JR. Current and future uses of neuroimaging for cognitively impaired patients. Lancet Neurol 2008; 7:161-72. [PMID: 18207114 DOI: 10.1016/s1474-4422(08)70019-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Technological advances have led to greater use of both structural and functional brain imaging to assist with the diagnosis of dementia for the increasing numbers of people with cognitive decline as they age. In current clinical practice, structural imaging (CT or MRI) is used to identify space-occupying lesions and stroke. Functional methods, such as PET scanning of glucose metabolism, could be used to differentiate Alzheimer's disease from frontotemporal dementia, which helps to guide clinicians in symptomatic treatment strategies. New neuroimaging methods that are currently being developed can measure specific neurotransmitter systems, amyloid plaque and tau tangle concentrations, and neuronal integrity and connectivity. Successful co-development of neuroimaging surrogate markers and preventive treatments might eventually lead to so-called brain-check scans for determining risk of cognitive decline, so that physicians can administer disease-modifying medications, vaccines, or other interventions to avoid future cognitive losses and to delay onset of disease.
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Affiliation(s)
- Gary W Small
- Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience and Human Behavior, University of California-Los Angeles, Los Angeles, California, USA.
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McGeown WJ, Shanks MF, Venneri A. Prolonged cholinergic enrichment influences regional cortical activation in early Alzheimer's disease. Neuropsychiatr Dis Treat 2008; 4:465-76. [PMID: 18728791 PMCID: PMC2518373 DOI: 10.2147/ndt.s2461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Neuroimaging studies of cholinesterase inhibitor (ChEI) treatment in Alzheimer's disease (AD) indicate that the short and long term actions of ChEIs are dissimilar. fMRI studies of the ChEI rivastigmine have focused on its short term action. In this exploratory study the effect of prolonged (20 weeks) rivastigmine treatment on regional brain activity was measured with fMRI in patients with mild AD. Eleven patients with probable AD and nine age-matched controls were assessed with a Pyramids and Palm Trees semantic association and an n-back working memory fMRI paradigm. In the patient group only, the assessment was repeated after 20 weeks of treatment. There was an increase in task-related brain activity after treatment with activations more like those of normal healthy elderly. Behaviorally, however, there were no significant differences between baseline and retest scores, with a range of performance probably reflecting variation in drug efficacy across patients. Variable patient response and drug dynamic/kinetic factors in small patient groups will inevitably bias (either way) the effect size of any relevant drug related changes in activation. Future studies should take drug response into account to provide more insight into the benefits of ChEI drugs at the individual level.
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Seltzer B. Is long-term treatment of Alzheimer's disease with cholinesterase inhibitor therapy justified? Drugs Aging 2008; 24:881-90. [PMID: 17953456 DOI: 10.2165/00002512-200724110-00001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The cholinesterase inhibitors (ChEIs) donepezil, rivastigmine and galantamine are the current mainstays in the drug treatment of Alzheimer's disease (AD). There is convincing evidence that these agents provide at least modest cognitive, behavioural and functional benefit for 6-12 months at all stages of the disease. Longer term benefits cannot be directly examined by placebo-controlled trials. Nevertheless, the results of virtually all open-label extensions of the pivotal trials, studies of patients with AD at different levels of severity and clinical trials using other designs favour treatment over no treatment for periods of up to 5 years. There are plausible biological reasons why ChEIs might be expected to work over a prolonged period of time although, to date, studies using various markers to chart the effects of medication on long-term disease progression have yielded mixed results. The most contentious issue regarding long-term treatment is economic, but the majority of available economic analyses suggest net savings over the long term if patients with AD receive persistent treatment with ChEIs.
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Affiliation(s)
- Ben Seltzer
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.
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Salmon E, Lekeu F, Bastin C, Garraux G, Collette F. Functional imaging of cognition in Alzheimer's disease using positron emission tomography. Neuropsychologia 2007; 46:1613-23. [PMID: 18191961 DOI: 10.1016/j.neuropsychologia.2007.11.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 11/11/2007] [Accepted: 11/28/2007] [Indexed: 01/18/2023]
Abstract
Positron emission tomography in Alzheimer's disease (AD) demonstrates a metabolic decrease, predominantly in associative posterior cortices (comprising the posterior cingulate cortex), and also involving medial temporal structures and frontal regions at a lesser degree. The level of activity in this wide network is roughly correlated with dementia severity, but several confounds (such as age, education or subcortical ischemic lesions) may influence the brain-behaviour relationship. Univariate analyses allow one to segregate brain regions that are particularly closely related to specific neuropsychological performances. For example, a relationship was established between the activity in lateral associative cortices and semantic performance in AD. The role of semantic capacities (subserved by temporal or parietal regions) in episodic memory tasks was also emphasized. The residual activity in medial temporal structures was related to episodic memory abilities, as measured by free recall performance, cued recall ability and recognition accuracy. More generally, AD patients' performance on episodic memory tasks was correlated with the metabolism in several structures of Papez's circuit (including the medial temporal and posterior cingulate regions). Multivariate analyses should provide complementary information on impaired metabolic covariance in functional networks of brain regions and the consequences for AD patients' cognitive performance. More longitudinal studies are being conducted that should tell us more about the prognostic value of initial metabolic impairment and the neural correlates of progressive deterioration of cognitive performance in AD.
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Affiliation(s)
- Eric Salmon
- Cyclotron Research Centre, University of Liège, B30 Sart Tilman, 4000 Liège, Belgium.
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Abstract
Acetylcholinesterase inhibitor drugs are now a mature treatment approach for Alzheimer’s disease, although they remain controversial. This review addresses the available data on acetylcholinesterase inhibitor treatment in patients with Alzheimer’s disease across multiple outcome types. It addresses rational and evidence-based expectations for treatment in this population.
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Affiliation(s)
- David S Geldmacher
- University of Virginia, Department of Neurology, PO Box 800394, Charlottesville, VA 22908, USA
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Irving EA, Upton N. Symptomatic treatment of Alzheimer’s disease: identification of biomarkers to aid translation from bench to bedside. Biomark Med 2007; 1:93-110. [DOI: 10.2217/17520363.1.1.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the absence of robust pharmacodynamic markers, the potential success of novel therapeutic agents for the symptomatic relief of Alzheimer’s disease is largely unknown until the drugs enter relatively large studies, assessing clinical outcome over a 6-month period. In order to increase the efficiency of future clinical development there is, therefore, a need to identify pharmacodynamic markers of drug response, pharmacodynamic models that allow early prediction of efficacy and markers to aid the stratification of the patient population. Using literature available from cholinesterase inhibitors, memantine and Ginkgo biloba, this review focuses on the identification of potential pharmacodynamic markers/models and highlights the utility of these end points throughout the drug discovery process, from preclinical to clinical development.
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Affiliation(s)
- Elaine A Irving
- GlaxoSmithKline, Neurology and GI CEDD, New Frontiers Science Park North, Third Avenue, Harlow, Essex, CM19 5AW, UK
| | - Neil Upton
- GlaxoSmithKline, Neurology and GI CEDD, New Frontiers Science Park North, Third Avenue, Harlow, Essex, CM19 5AW, UK
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Kadir A, Darreh-Shori T, Almkvist O, Wall A, Långström B, Nordberg A. Changes in brain 11C-nicotine binding sites in patients with mild Alzheimer's disease following rivastigmine treatment as assessed by PET. Psychopharmacology (Berl) 2007; 191:1005-14. [PMID: 17310387 DOI: 10.1007/s00213-007-0725-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Accepted: 01/24/2007] [Indexed: 10/23/2022]
Abstract
RATIONALE Marked reduction in the cortical nicotinic acetylcholine receptors is observed in the brain of patients suffering from Alzheimer's disease (AD). Although cholinesterase inhibitors are used for symptomatic treatment of mild to moderate AD patients, numerous long-term treatment studies indicate that they might stabilize or halt the progression of the disease by restoring the central cholinergic neurotransmission. Thus, we used positron emission tomography (PET) technique as a sensitive approach to assess longitudinal changes in the nicotine binding sites in the brains of patients with AD. OBJECTIVE To evaluate changes in brain nicotinic binding sites in relation to inhibition level of cholinesterases in cerebrospinal fluid (CSF) and plasma and changes in cognitive performance of the patients in different neuropsychological tests after rivastigmine treatment. MATERIALS AND METHODS Ten mild AD patients received rivastigmine for 12 months. A dual-tracer PET model with administration of (15)O-water and (S)(-)(11)C-nicotine was used to assess (11)C-nicotine binding sites in the brain at baseline and after 3 and 12 months of the treatment. Cholinesterase activities in CSF and plasma were assessed colorimetrically. RESULTS The (11)C-nicotine binding sites were significantly increased 12-19% in several cortical brain regions after 3 months compared with baseline, while the increase was not significant after 12 months of the treatment. After 3 months treatment, low enzyme inhibition in CSF and plasma was correlated with higher cortical (11)C-nicotine binding. The (11)C-nicotine binding positively correlated with attentional task at the 12-month follow-up. CONCLUSION Changes in the (11)C-nicotine binding during rivastigmine treatment might represent remodeling of the cholinergic and related neuronal network.
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Affiliation(s)
- Ahmadul Kadir
- Karolinska Institute, Department of Neurobiology, Care Sciences and Society, Division of Molecular Neuropharmacology, Karolinska University Hospital Huddinge, Novum Floor-5, 141 86, Stockholm, Sweden
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Abstract
Alzheimer's disease (AD) is the commonest form of degenerative dementia and is characterised by progressive cognitive decline. Despite extensive research, the cause of AD is unknown and there is no cure at present. Of the deficits found in AD, that affecting the cholinergic neurotransmitter system is the best established and the only one translated into symptomatic treatment. Cholinergic enhancement with cholinesterase inhibitor (ChEI) drugs has been achieved and their efficacy and safety ascertained by conventional clinical trials. The mechanism of action of these drugs, however, is not well understood. Imaging with SPECT, PET, MRI and fMRI after treatment has clarified what happens in the brains of those AD patients treated with ChEI drugs. Studies with these techniques have identified increases in brain blood flow and glucose metabolism, restoration of nicotinic receptor function and re-establishment of task-related regional brain activation in response to cognitive stimulation after treatment. Structural MRI studies have explained, to some degree, why only a proportion of patients benefits from ChEI treatment and there is some evidence that some ChEI drugs might be neuroprotective. There are, however, many unsolved problems. Timing of treatment intervention to obtain maximum response and the determinants of treatment response are mostly unknown. It is also unclear whether administration of treatment in those patients who have no potential for response accelerates disease progression. These issues cannot be solved by conventional clinical trials. Pharmacoimaging studies could assist the development and refinement of drugs to treat those diseases, such as AD, which affect the central nervous system.
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Affiliation(s)
- Annalena Venneri
- Clinical Neuroscience Centre, University of Hull, HU6 7RX Hull, UK.
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Shanks MF, McGeown WJ, Forbes-McKay KE, Waiter GD, Ries M, Venneri A. Regional brain activity after prolonged cholinergic enhancement in early Alzheimer's disease. Magn Reson Imaging 2007; 25:848-59. [PMID: 17442521 DOI: 10.1016/j.mri.2007.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2007] [Indexed: 11/29/2022]
Abstract
This functional magnetic resonance imaging (fMRI) study examined changes in brain activation after prolonged (20 weeks) and stabilized treatment with the cholinesterase inhibitor galantamine in a small group of patients with very mild Alzheimer's disease (AD). Two cognitive activation paradigms were chosen: one requiring semantic association and the other relying on attention and requiring target detection. A group of age- and education-matched healthy controls was also scanned for comparison. A modest (but not statistically significant) improvement in behavioral scores after treatment was observed in both fMRI tasks. There were brain activation increases in the semantic association task after treatment, and the differences in brain activation present in the comparison of AD patients' baseline images with those of controls were not detectable after treatment. In the target detection task, regions that were activated in the elderly controls but not in the baseline images of the AD group also showed significant activation after treatment. Overall, however, the increases were modest and might reflect the heterogeneity of clinical response to treatment in this small group. Future pharmacological fMRI studies should include clinical response as a factor in the analysis of cholinergic enhancement effects in AD patients.
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Affiliation(s)
- Michael F Shanks
- Clinical Neuroscience Centre, University of Hull, HU6 7RX Hull, UK
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Modrego PJ, Pina MA, Fayed N, Díaz M. Changes in metabolite ratios after treatment with rivastigmine in Alzheimer's disease: a nonrandomised controlled trial with magnetic resonance spectroscopy. CNS Drugs 2007; 20:867-77. [PMID: 16999455 DOI: 10.2165/00023210-200620100-00006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
BACKGROUND Alzheimer's disease is associated with abnormalities in the levels of some brain metabolites, including decreases in N-acetyl-aspartate (NAA) and increases in myo-inositol and choline levels. Cholinesterase inhibitors have proven modest effects on cognition in patients with mild or moderate Alzheimer's disease; however, there is little information on the effects of these drugs on metabolic parameters in the brain. Magnetic resonance spectroscopy (MRS) provides a method of determining changes in such parameters. OBJECTIVE To assess the effect of rivastigmine on metabolite levels in different areas of the brain, and whether changes in metabolite levels correlate with clinical outcome, in patients with Alzheimer's disease compared with untreated patients with Alzheimer's disease. METHODS Twenty-four consecutive patients with mild or moderate Alzheimer's disease were enrolled in the study and were treated with rivastigmine at a target dosage of 12 mg/day for 4 months. A comparison group of ten consecutive untreated patients with Alzheimer's disease with similar cognitive impairment to the treatment group were also enrolled. Each patient underwent assessment using the Mini-Mental State Examination (Spanish version), the Blessed Dementia Rating Scale, the Clinical Dementia Rating scale, the Interview for Deterioration in Daily living activities in Dementia, the Alzheimer's Disease Assessment Scale cognitive and noncognitive subscales, and single-voxel MRS of the frontal, parietal and occipital cortices of the brain to assess levels of brain metabolites (NAA, creatine, choline and myo-inositol) and their ratios to creatine. All assessments were performed at baseline and after 4 months of treatment with rivastigmine, and at baseline and 1 month later in the comparison group. RESULTS Globally, although there was some mean improvement, no significant changes in the cognitive and noncognitive scale scores between baseline and post-treatment assessments were seen in patients who received rivastigmine. A significant increase in the NAA/creatine ratio in the frontal cortex (1.23 at baseline vs 1.3 after treatment; p = 0.026) and in the myo-inositol/creatine ratio in the occipital cortex (0.61 vs 0.65; p = 0.009) was seen in rivastigmine-treated patients. No other significant changes in the metabolite levels or their ratios to creatine were seen in these patients. After correction for multiple comparisons, the significant effects disappeared. Only in the frontal cortex did the changes in metabolite ratios correlate with changes on the clinical scales. In the comparison group, no significant differences between the metabolite levels or ratios to creatine seen with the two scans were detected. CONCLUSION Treatment with rivastigmine showed modest neuronal functional recovery in the frontal cortex only (being able to reverse disease-related decreases in NAA/creatine ratio in this area but unable to affect the disease-related increase in myo-inositol/creatine ratio in any cortex). Since the modest clinical changes correlated with the small changes in the metabolite rates, MRS could be useful in monitoring response to current or future treatments for Alzheimer's disease.
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Teipel SJ, Drzezga A, Bartenstein P, Möller HJ, Schwaiger M, Hampel H. Effects of donepezil on cortical metabolic response to activation during (18)FDG-PET in Alzheimer's disease: a double-blind cross-over trial. Psychopharmacology (Berl) 2006; 187:86-94. [PMID: 16767418 DOI: 10.1007/s00213-006-0408-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Accepted: 03/19/2006] [Indexed: 11/25/2022]
Abstract
RATIONALE Cholinergic enhancement is among the best established treatments of Alzheimer's disease (AD). The cognitive effects of treatment are thought to be mediated by improvement of neuronal transmission. Positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) by measuring cortical metabolic response to activation assesses integrity of neuronal transmission in vivo. OBJECTIVE To determine the effects of treatment with donepezil, a centrally selective acetylcholinesterase inhibitor, on cortical metabolism in AD using 18FDG-PET. METHODS We enrolled 23 patients, 18 of which completed the study, with mild to moderate probable AD (mini-mental status exam scores of 15-28, inclusive) in a double-blind cross over trial of 8 weeks donepezil compared to 8 weeks placebo with repeated double 18FDG-PET examinations during passive audio-visual stimulation. Effects of treatment on cortical metabolic response to stimulation were determined with a linear model on a voxel level using Statistical Parametric Mapping (SPM 99, Wellcome Department of Imaging Neuroscience, London). RESULTS Effects of treatment on cognitive measures were not different between donepezil and placebo. During passive audio-visual stimulation, patients showed activation in posterior visual and auditory areas and decreased activation in frontal cortex and basal ganglia. Resting state metabolism was increased with donepezil in left prefrontal cortex and decreased in right hippocampus. Cortical response to activation was increased in right hippocampus with donepezil compared to placebo. CONCLUSION Donepezil treatment shows a spatially limited functional effect on right hippocampus and left prefrontal cortical metabolism, independently of clinical response to treatment.
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Affiliation(s)
- Stefan J Teipel
- Alzheimer Memorial Center, Department of Psychiatry, Ludwig-Maximilian University, Nussbaumstr. 7, 80336 Munich, Germany.
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