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Huang YY, Gan YH, Yang L, Cheng W, Yu JT. Depression in Alzheimer's Disease: Epidemiology, Mechanisms, and Treatment. Biol Psychiatry 2024; 95:992-1005. [PMID: 37866486 DOI: 10.1016/j.biopsych.2023.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/13/2023] [Accepted: 10/07/2023] [Indexed: 10/24/2023]
Abstract
Depression and Alzheimer's disease (AD) are substantial public health concerns. In the past decades, a link between the 2 disease entities has received extensive acknowledgment, yet the complex nature of this relationship demands further clarification. Some evidence indicates that midlife depression may be an AD risk factor, while a chronic course of depression in late life may be a precursor to or symptom of dementia. Recently, multiple pathophysiological mechanisms have been proposed to underlie the bidirectional relationship between depression and AD, including genetic predisposition, immune dysregulation, accumulation of AD-related biomarkers (e.g., amyloid-β and tau), and alterations in brain structure. Accordingly, numerous therapeutic approaches, such as pharmacology treatments, psychotherapy, and lifestyle interventions, have been suggested as potential means of interfering with these pathways. However, the current literature on this topic remains fragmented and lacks a comprehensive review characterizing the association between depression and AD. In this review, we aim to address these gaps by providing an overview of the co-occurrence and temporal relationship between depression and AD, as well as exploring their underlying mechanisms. We also examine the current therapeutic regimens for depression and their implications for AD management and outline key challenges facing the field.
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Affiliation(s)
- Yu-Yuan Huang
- Department of Neurology and National Center for Neurological Disorders, Huashan Hospital, State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yi-Han Gan
- Department of Neurology and National Center for Neurological Disorders, Huashan Hospital, State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Liu Yang
- Department of Neurology and National Center for Neurological Disorders, Huashan Hospital, State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wei Cheng
- Institute of Science and Technology for Brain-Inspired Intelligence, Department of Neurology and National Center for Neurological Disorders, Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China
| | - Jin-Tai Yu
- Department of Neurology and National Center for Neurological Disorders, Huashan Hospital, State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Shanghai Medical College, Fudan University, Shanghai, China.
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Loh JS, Mak WQ, Tan LKS, Ng CX, Chan HH, Yeow SH, Foo JB, Ong YS, How CW, Khaw KY. Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases. Signal Transduct Target Ther 2024; 9:37. [PMID: 38360862 PMCID: PMC10869798 DOI: 10.1038/s41392-024-01743-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 01/02/2024] [Accepted: 01/14/2024] [Indexed: 02/17/2024] Open
Abstract
The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.
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Affiliation(s)
- Jian Sheng Loh
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Wen Qi Mak
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Li Kar Stella Tan
- School of Pharmacy, Faculty of Health & Medical Sciences, Taylor's University, 1, Jalan Taylors, Subang Jaya, 47500, Selangor, Malaysia
- Digital Health & Medical Advancements, Taylor's University, 1, Jalan Taylors, Subang Jaya, 47500, Selangor, Malaysia
| | - Chu Xin Ng
- School of Biosciences, Faculty of Health & Medical Sciences, Taylor's University, 1, Jalan Taylors, Subang Jaya, 47500, Selangor, Malaysia
| | - Hong Hao Chan
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Shiau Hueh Yeow
- UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London, WC1N 1AX, UK
| | - Jhi Biau Foo
- School of Pharmacy, Faculty of Health & Medical Sciences, Taylor's University, 1, Jalan Taylors, Subang Jaya, 47500, Selangor, Malaysia
- Digital Health & Medical Advancements, Taylor's University, 1, Jalan Taylors, Subang Jaya, 47500, Selangor, Malaysia
| | - Yong Sze Ong
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Chee Wun How
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia.
| | - Kooi Yeong Khaw
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia.
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Sawant N, Kshirsagar S, Reddy PH, Reddy AP. Protective effects of SSRI, Citalopram in mutant APP and mutant Tau expressed dorsal raphe neurons in Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166942. [PMID: 37931714 DOI: 10.1016/j.bbadis.2023.166942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 10/05/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023]
Abstract
Depression is among the most common neuropsychiatric comorbidities in Alzheimer's disease (AD) and other Tauopathies. Apart from its anti-depressive and anxiolytic effects, selective serotonin reuptake inhibitor (SSRI) treatment also offers intracellular modifications that may help to improve neurogenesis, reduce amyloid burden & Tau pathologies, and neuroinflammation in AD. Despite its multifaceted impact in the brain, the exact physiological and molecular mechanism by which SSRIs such as Citalopram improve neurogenesis and synaptogenesis in dementia is poorly understood. In the current study, we investigated the protective role of SSRI, Citalopram, in serotonergic, medullary raphe neurons (RN46A-B14). RN46A-B14 cells were transfected with wild-type and mutant APP and Tau cDNAs for 24 h and then treated with 20 μM Cit for 24 h. We then assessed mRNA and protein levels of pTau, total Tau, serotonin related proteins such as TPH2, SERT, and 5HTR1a, synaptic proteins and the cytoskeletal structure. We also assessed cell survival, mitochondrial respiration and mitochondrial morphology. The mutant APP and Tau transfected cells showed increased levels of serotonin related proteins and mRNA, while the mRNA and protein levels of synaptic proteins were downregulated. Citalopram treatment significantly reduced pathologically pTau level along with the serotonin related protein levels. On the other hand, there was a significant increase in the mRNA and protein levels of synaptic genes and cytoskeletal structure in the treated groups. Further, Citalopram also improved cell survival, mitochondrial respiration and mitochondrial morphology in the treated cells that express mAPP and mTau. Taken together these findings suggest Citalopram could not only be a promising therapeutic drug for treating patients with depression, but also for AD patients.
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Affiliation(s)
- Neha Sawant
- Nutritional Sciences Department, Texas Tech University, Lubbock, TX, USA; Internal Medicine Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sudhir Kshirsagar
- Internal Medicine Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - P Hemachandra Reddy
- Nutritional Sciences Department, Texas Tech University, Lubbock, TX, USA; Internal Medicine Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; Pharmacology & Neuroscience Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; Neurology Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; Speech, Language and Hearing Sciences Departments, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA; Public Health Department, School of Population and Public Health, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Arubala P Reddy
- Nutritional Sciences Department, Texas Tech University, Lubbock, TX, USA.
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Singh AK, Malviya R, Prakash A, Verma S. Neuropsychiatric Manifestations in Alzheimer's Disease Patients: Genetics and Treatment Options. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2024; 23:39-54. [PMID: 36856177 DOI: 10.2174/1871527322666230301111216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 12/03/2022] [Accepted: 12/27/2022] [Indexed: 03/02/2023]
Abstract
BACKGROUND Alzheimer's disease (AD) is characterized by neuropsychiatric symptoms (NPS), which cause great misery to those with dementia and those who care for them and may lead to early institutionalization. OBJECTIVE The present systematic review aims to discuss the various aspects of Alzheimer's, including treatment options. METHODS The databases Embase, PubMed, and Web of Science were searched to collect data. RESULTS Incipient cognitive deterioration is commonly accompanied by these early warning signals of neurocognitive diseases. The neurobiology of NPSs in Alzheimer's disease, as well as particular symptoms, including psychosis, agitation, apathy, sadness, and sleep disorders, will be examined in this review. For NPSs in Alzheimer's disease, clinical trial designs, as well as regulatory issues, were also addressed. A fresh wave of research, however, is helping to push the discipline ahead. For medication development and repurposing, we highlight the most recent results in genetics, neuroimaging, and neurobiology. Even though identifying and treating psychosis in adults with dementia is still a challenging endeavor, new options are coming up that give the field fresh focus and hope. Conclsuion: It can be concluded from the complete literature survey that Alzheimer's-related psychosis as well as other symptoms that are not psychotic, have made significant progress in the last decade. These milestones in the development of safer, more effective treatments have been achieved as a consequence of great focus on non-pharmacological interventions like DICE or WHELD; the investigation into ways to improve existing drugs like aripiprazole, risperidone, amisulpride, and Escitalopram for safer precision-based treatment; and the development of a clinical trial program for pimavanserin.
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Affiliation(s)
- Arun Kumar Singh
- Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University Greater Noida, Uttar Pradesh, India
| | - Rishabha Malviya
- Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University Greater Noida, Uttar Pradesh, India
| | - Anuj Prakash
- Reference Standard Division, Indian Pharmacopoeia Commission, Sec-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India
| | - Swati Verma
- Department of Pharmacy, School of Medical and Allied Sciences, Galgotias University Greater Noida, Uttar Pradesh, India
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Post Z, Manfready RA, Keshavarzian A. Overview of the Gut-Brain Axis: From Gut to Brain and Back Again. Semin Neurol 2023; 43:506-517. [PMID: 37562457 DOI: 10.1055/s-0043-1771464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
The gut-brain axis refers to a bidirectional communication pathway linking the gastrointestinal system to the central nervous system. The hardware of this multifaceted pathway takes many forms, at once structural (neurons, microglia, intestinal epithelial cell barrier), chemical (neurotransmitters, enteroendocrine hormones, bacterial metabolites), and cellular (immune signaling, inflammatory pathways). The gut-brain axis is exquisitely influenced by our environment, diet, and behaviors. Here, we will describe recent progress in understanding the gut-brain axis in neurological disease, using Parkinson's disease as a guide. We will see that each component of the gut-brain axis is heavily mediated by intestinal microbiota and learn how gut-brain communication can go awry in microbial dysbiosis.
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Affiliation(s)
- Zoë Post
- Division of Digestive Diseases and Nutrition, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois
| | - Richard A Manfready
- Division of Digestive Diseases and Nutrition, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, Illinois
- Departments of Physiology and Anatomy & Cell Biology, Rush University Medical Center, Chicago, Illinois
| | - Ali Keshavarzian
- Division of Digestive Diseases and Nutrition, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, Illinois
- Departments of Physiology and Anatomy & Cell Biology, Rush University Medical Center, Chicago, Illinois
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Novotny BC, Fernandez MV, Wang C, Budde JP, Bergmann K, Eteleeb AM, Bradley J, Webster C, Ebl C, Norton J, Gentsch J, Dube U, Wang F, Morris JC, Bateman RJ, Perrin RJ, McDade E, Xiong C, Chhatwal J, Goate A, Farlow M, Schofield P, Chui H, Karch CM, Cruchaga C, Benitez BA, Harari O. Metabolomic and lipidomic signatures in autosomal dominant and late-onset Alzheimer's disease brains. Alzheimers Dement 2023; 19:1785-1799. [PMID: 36251323 PMCID: PMC10106526 DOI: 10.1002/alz.12800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 07/21/2022] [Accepted: 08/09/2022] [Indexed: 02/05/2023]
Abstract
INTRODUCTION The identification of multiple genetic risk factors for Alzheimer's disease (AD) suggests that many pathways contribute to AD onset and progression. However, the metabolomic and lipidomic profiles in carriers of distinct genetic risk factors are not fully understood. The metabolome can provide a direct image of dysregulated pathways in the brain. METHODS We interrogated metabolomic signatures in the AD brain, including carriers of pathogenic variants in APP, PSEN1, and PSEN2 (autosomal dominant AD; ADAD), APOE ɛ4, and TREM2 risk variant carriers, and sporadic AD (sAD). RESULTS We identified 133 unique and shared metabolites associated with ADAD, TREM2, and sAD. We identified a signature of 16 metabolites significantly altered between groups and associated with AD duration. DISCUSSION AD genetic variants show distinct metabolic perturbations. Investigation of these metabolites may provide greater insight into the etiology of AD and its impact on clinical presentation. HIGHLIGHTS APP/PSEN1/PSEN2 and TREM2 variant carriers show distinct metabolic changes. A total of 133 metabolites were differentially abundant in AD genetic groups. β-citrylglutamate is differentially abundant in autosomal dominant, TREM2, and sporadic AD. A 16-metabolite profile shows differences between Alzheimer's disease (AD) genetic groups. The identified metabolic profile is associated with duration of disease.
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Affiliation(s)
- Brenna C. Novotny
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Maria Victoria Fernandez
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ciyang Wang
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
- Division of Biology & Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri, USA
| | - John P. Budde
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kristy Bergmann
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Abdallah M. Eteleeb
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joseph Bradley
- Division of Biology & Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Carol Webster
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Curtis Ebl
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joanne Norton
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jen Gentsch
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Umber Dube
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Fengxian Wang
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - John C. Morris
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Randall J. Bateman
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Richard J. Perrin
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Eric McDade
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chengjie Xiong
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jasmeer Chhatwal
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Alzheimer’s Disease Neuroimaging Initiative
- Data used in the preparation of this article were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in the analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf
| | - Alzheimer’s Disease Metabolomics Consortium (ADMC)
- Data used in the preparation of this article were generated by the Alzheimer’s Disease Metabolomics Consortium (ADMC). As such, the investigators within the ADMC provided data but did not participate in the analysis or writing of this report. A complete listing of ADMC investigators can be found at: https://sites.duke.edu/adnimetab/team/
| | - Alison Goate
- Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Martin Farlow
- Department of Neurology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Peter Schofield
- Neuroscience Research Australia, Randwick, Sydney, NSW, Australia
| | - Helena Chui
- Neurology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Celeste M. Karch
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Carlos Cruchaga
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bruno A. Benitez
- Department of Neurology, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Oscar Harari
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri, USA
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, Missouri, USA
- The Charles F. and Joanne Knight Alzheimer Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, USA
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Montero-Cosme TG, Pascual-Mathey LI, Hernández-Aguilar ME, Herrera-Covarrubias D, Rojas-Durán F, Aranda-Abreu GE. Potential drugs for the treatment of Alzheimer's disease. Pharmacol Rep 2023; 75:544-559. [PMID: 37005970 DOI: 10.1007/s43440-023-00481-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/24/2023] [Accepted: 03/26/2023] [Indexed: 04/04/2023]
Abstract
It is well known that amyloid precursor protein (APP), the enzyme β-secretase 1 (BACE1), cyclooxygenase 2 (COX-2), nicastrin (NCT), and hyperphosphorylated tau protein (p-tau) are closely related to the development of Alzheimer's disease (AD). In addition, recent evidence shows that neuroinflammation also contributes to the pathogenesis of AD. Although the mechanism is not clearly known, such inflammation could alter the activity of the aforementioned molecules. Therefore, the use of anti-inflammatory agents could slow the progression of the disease. Nimesulide, resveratrol, and citalopram are three anti-inflammatory agents that could contribute to a decrease in neuroinflammation and consequently to a decrease in the overexpression of APP, BACE1, COX-2, NCT, and p-Tau, as they possess anti-inflammatory effects that could regulate the expression of APP, BACE1, COX-2, NCT, and p-Tau of potent pro-inflammatory markers indirectly involved in the expression of APP, BACE1, NCT, COX-2, and p-Tau; therefore, their use could be beneficial as preventive treatment as well as in the early stages of AD.
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Affiliation(s)
| | | | | | | | - Fausto Rojas-Durán
- Instituto de Investigaciones Cerebrales, Universidad Veracruzana, Xalapa, Veracruz, México
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The Synergic Effect of AT(N) Profiles and Depression on the Risk of Conversion to Dementia in Patients with Mild Cognitive Impairment. Int J Mol Sci 2023; 24:ijms24021371. [PMID: 36674881 PMCID: PMC9865785 DOI: 10.3390/ijms24021371] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/02/2023] [Accepted: 01/06/2023] [Indexed: 01/13/2023] Open
Abstract
Few studies have addressed the impact of the association between Alzheimer's disease (AD) biomarkers and NPSs in the conversion to dementia in patients with mild cognitive impairment (MCI), and no studies have been conducted on the interaction effect of these two risk factors. AT(N) profiles were created using AD-core biomarkers quantified in cerebrospinal fluid (CSF) (normal, brain amyloidosis, suspected non-Alzheimer pathology (SNAP) and prodromal AD). NPSs were assessed using the Neuropsychiatric Inventory Questionnaire (NPI-Q). A total of 500 individuals with MCI were followed-up yearly in a memory unit. Cox regression analysis was used to determine risk of conversion, considering additive and multiplicative interactions between AT(N) profile and NPSs on the conversion to dementia. A total of 224 participants (44.8%) converted to dementia during the 2-year follow-up study. Pathologic AT(N) groups (brain amyloidosis, prodromal AD and SNAP) and the presence of depression and apathy were associated with a higher risk of conversion to dementia. The additive combination of the AT(N) profile with depression exacerbates the risk of conversion to dementia. A synergic effect of prodromal AD profile with depressive symptoms is evidenced, identifying the most exposed individuals to conversion among MCI patients.
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Smith GS, Protas H, Kuwabara H, Savonenko A, Nassery N, Gould NF, Kraut M, Avramopoulos D, Holt D, Dannals RF, Nandi A, Su Y, Reiman EM, Chen K. Molecular imaging of the association between serotonin degeneration and beta-amyloid deposition in mild cognitive impairment. Neuroimage Clin 2023; 37:103322. [PMID: 36680976 PMCID: PMC9869478 DOI: 10.1016/j.nicl.2023.103322] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 12/28/2022] [Accepted: 01/05/2023] [Indexed: 01/07/2023]
Abstract
BACKGROUND Degeneration of the serotonin system has been observed in Alzheimer's disease (AD) and in mild cognitive impairment (MCI). In transgenic amyloid mouse models, serotonin degeneration is detected prior to widespread cortical beta-amyloid (Aβ) deposition, also suggesting that serotonin degeneration may be observed in preclinical AD. METHODS The differences in the distribution of serotonin degeneration (reflected by the loss of the serotonin transporter, 5-HTT) relative to Aβ deposition was measured with positron emission tomography in a group of individuals with MCI and a group of healthy older adults. A multi-modal partial least squares (mmPLS) algorithm was applied to identify the spatial covariance pattern between 5-HTT availability and Aβ deposition. RESULTS Forty-five individuals with MCI and 35 healthy older adults were studied, 22 and 27 of whom were included in the analyses who were "amyloid positive" and "amyloid negative", respectively. A pattern of lower cortical, subcortical and limbic 5-HTT availability and higher cortical Aβ deposition distinguished the MCI from the healthy older control participants. Greater expression of this pattern was correlated with greater deficits in memory and executive function in the MCI group, not in the control group. CONCLUSION A spatial covariance pattern of lower 5-HTT availability and Aβ deposition was observed to a greater extent in an MCI group relative to a control group and was associated with cognitive impairment in the MCI group. The results support the application of mmPLS to understand the neurochemical changes associated with Aβ deposition in the course of preclinical AD.
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Affiliation(s)
- Gwenn S Smith
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | | | - Hiroto Kuwabara
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alena Savonenko
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Najlla Nassery
- Division of General Internal Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neda F Gould
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael Kraut
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dimitri Avramopoulos
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel Holt
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert F Dannals
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ayon Nandi
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yi Su
- Banner Alzheimer's Institute, Phoenix, AZ, USA
| | | | - Kewei Chen
- Banner Alzheimer's Institute, Phoenix, AZ, USA
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10
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Mumtaz I, Ayaz MO, Khan MS, Manzoor U, Ganayee MA, Bhat AQ, Dar GH, Alghamdi BS, Hashem AM, Dar MJ, Ashraf GM, Maqbool T. Clinical relevance of biomarkers, new therapeutic approaches, and role of post-translational modifications in the pathogenesis of Alzheimer's disease. Front Aging Neurosci 2022; 14:977411. [PMID: 36158539 PMCID: PMC9490081 DOI: 10.3389/fnagi.2022.977411] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/18/2022] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder that causes progressive loss of cognitive functions like thinking, memory, reasoning, behavioral abilities, and social skills thus affecting the ability of a person to perform normal daily functions independently. There is no definitive cure for this disease, and treatment options available for the management of the disease are not very effective as well. Based on histopathology, AD is characterized by the accumulation of insoluble deposits of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs). Although several molecular events contribute to the formation of these insoluble deposits, the aberrant post-translational modifications (PTMs) of AD-related proteins (like APP, Aβ, tau, and BACE1) are also known to be involved in the onset and progression of this disease. However, early diagnosis of the disease as well as the development of effective therapeutic approaches is impeded by lack of proper clinical biomarkers. In this review, we summarized the current status and clinical relevance of biomarkers from cerebrospinal fluid (CSF), blood and extracellular vesicles involved in onset and progression of AD. Moreover, we highlight the effects of several PTMs on the AD-related proteins, and provide an insight how these modifications impact the structure and function of proteins leading to AD pathology. Finally, for disease-modifying therapeutics, novel approaches, and targets are discussed for the successful treatment and management of AD.
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Affiliation(s)
- Ibtisam Mumtaz
- Laboratory of Nanotherapeutics and Regenerative Medicine, Department of Nanotechnology, University of Kashmir, Srinagar, India
| | - Mir Owais Ayaz
- Laboratory of Cell and Molecular Biology, Department of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, India
- Centre for Scientific and Innovative Research, Ghaziabad, Utter Pradesh, India
| | - Mohamad Sultan Khan
- Neurobiology and Molecular Chronobiology Laboratory, Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Umar Manzoor
- Laboratory of Immune and Inflammatory Disease, Jeju Research Institute of Pharmaceutical Sciences, Jeju National University, Jeju, South Korea
| | - Mohd Azhardin Ganayee
- Laboratory of Nanotherapeutics and Regenerative Medicine, Department of Nanotechnology, University of Kashmir, Srinagar, India
- Department of Chemistry, Indian Institute of Technology Madras, Chennai, India
| | - Aadil Qadir Bhat
- Laboratory of Cell and Molecular Biology, Department of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, India
- Centre for Scientific and Innovative Research, Ghaziabad, Utter Pradesh, India
| | - Ghulam Hassan Dar
- Sri Pratap College, Cluster University Srinagar, Jammu and Kashmir, India
| | - Badrah S. Alghamdi
- Department of Physiology, Neuroscience Unit, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
- Pre-clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Anwar M. Hashem
- Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
- Vaccines and Immunotherapy Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohd Jamal Dar
- Laboratory of Cell and Molecular Biology, Department of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, India
- Centre for Scientific and Innovative Research, Ghaziabad, Utter Pradesh, India
| | - Gulam Md. Ashraf
- Pre-clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Tariq Maqbool
- Laboratory of Nanotherapeutics and Regenerative Medicine, Department of Nanotechnology, University of Kashmir, Srinagar, India
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11
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Serotonin 5-HT 6 Receptor Ligands and Butyrylcholinesterase Inhibitors Displaying Antioxidant Activity-Design, Synthesis and Biological Evaluation of Multifunctional Agents against Alzheimer's Disease. Int J Mol Sci 2022; 23:ijms23169443. [PMID: 36012707 PMCID: PMC9409043 DOI: 10.3390/ijms23169443] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/18/2022] [Accepted: 08/20/2022] [Indexed: 11/17/2022] Open
Abstract
Neurodegeneration leading to Alzheimer’s disease results from a complex interplay of a variety of processes including misfolding and aggregation of amyloid beta and tau proteins, neuroinflammation or oxidative stress. Therefore, to address more than one of these, drug discovery programmes focus on the development of multifunctional ligands, preferably with disease-modifying and symptoms-reducing potential. Following this idea, herein we present the design and synthesis of multifunctional ligands and biological evaluation of their 5-HT6 receptor affinity (radioligand binding assay), cholinesterase inhibitory activity (spectroscopic Ellman’s assay), antioxidant activity (ABTS assay) and metal-chelating properties, as well as a preliminary ADMET properties evaluation. Based on the results we selected compound 14 as a well-balanced and potent 5-HT6 receptor ligand (Ki = 22 nM) and human BuChE inhibitor (IC50 = 16 nM) with antioxidant potential expressed as a reduction of ABTS radicals by 35% (150 μM). The study also revealed additional metal-chelating properties of compounds 15 and 18. The presented compounds modulating Alzheimer’s disease-related processes might be further developed as multifunctional ligands against the disease.
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12
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Bouter Y, Bouter C. Selective Serotonin Reuptake Inhibitor-Treatment Does Not Show Beneficial Effects on Cognition or Amyloid Burden in Cognitively Impaired and Cognitively Normal Subjects. Front Aging Neurosci 2022; 14:883256. [PMID: 35813957 PMCID: PMC9260503 DOI: 10.3389/fnagi.2022.883256] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 05/24/2022] [Indexed: 11/15/2022] Open
Abstract
Preclinical studies indicate that selective serotonin reuptake inhibitors (SSRI) have beneficial effects on Alzheimer-related pathologies. Therefore, the aim of this study was to evaluate the influence of SSRI-treatment on amyloid burden in 18F-Florbetapir-positron emission tomography (PET) and on cognition in cognitively normal and cognitively impaired subjects. We included n = 755 cognitively impaired and n = 394 cognitively normal participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) that underwent at least one 18F-Florbetapir-PET. Standardized uptake ratios (SUVR) and the Alzheimer Disease Assessment Scale-cognitive subscale (ADAS) scores as well as follow-up results were compared between subgroups with a history of SSRI-treatment (SSRI+) and without SSRI-treatment (SSRI-) as well as in subgroups of SSRI+/Depression+ and SSRI+/Depression- and SSRI-/Depression+ and SSRI-/Depression-. 18F-Florbetapir-PET did not show significant differences of SUVR between the SSRI+ and SSRI- groups in both, cognitively impaired and cognitively normal participants. There were no differences in subgroups of SSRI+/Depression+ and SSRI+/Depression- and SSRI-/Depression+ and SSRI-/Depression-. However, SUVR showed a dose-dependent inverse correlation to the duration of medication in cognitively normal and in cognitively impaired patients. SRRI-treatment did not show an effect on ADAS scores. Furthermore, there was no effect on follow-up SUVR or on follow-up ADAS scores. Overall, SSRI-treatment did not show beneficial effects on amyloid load nor on cognition.
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Affiliation(s)
- Yvonne Bouter
- Department of Psychiatry and Psychotherapy, University Medical Center Göttingen (UMG), Georg-August-University, Göttingen, Germany
| | - Caroline Bouter
- Department of Nuclear Medicine, University Medical Center Göttingen (UMG), Georg-August-University, Göttingen, Germany
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13
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Sivasaravanaparan M, Olesen LØ, Severino M, von Linstow MCU, Lambertsen KL, Gramsbergen JB, Hasselstrøm J, Metaxas A, Wiborg O, Finsen B. Efficacy of Chronic Paroxetine Treatment in Mitigating Amyloid Pathology and Microgliosis in APPSWE/PS1ΔE9 Transgenic Mice. J Alzheimers Dis 2022; 87:685-699. [PMID: 35342093 DOI: 10.3233/jad-220019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Modulation of serotonergic signaling by treatment with selective serotonin reuptake inhibitors (SSRIs) has been suggested to mitigate amyloid-β (Aβ) pathology in Alzheimer's disease, in addition to exerting an anti-depressant action. OBJECTIVE To investigate the efficacy of chronic treatment with the SSRI paroxetine, in mitigating Aβ pathology and Aβ plaque-induced microgliosis in the hippocampus of 18-month-old APPswe/PS1 ΔE9 mice. METHODS Plaque-bearing APPswe/PS1 ΔE9 and wildtype mice were treated with paroxetine per os at a dose of 5 mg/kg/day, from 9 to 18 months of age. The per os treatment was monitored by recording of the body weights and serum paroxetine concentrations, and by assessment of the serotonin transporter occupancy by [3H]DASB-binding in wildtype mice. Additionally, 5,7-dihydroxytryptamine was administered to 9-month-old APPswe/PS1 ΔE9 mice, to examine the effect of serotonin depletion on Aβ pathology. Aβ pathology was evaluated by Aβ plaque load estimation and the Aβ 42/Aβ 40 ratio by ELISA. RESULTS Paroxetine treatment led to > 80% serotonin transporter occupancy. The treatment increased the body weight of wildtype mice, but not of APPswe/PS1 ΔE9 mice. The treatment had no effect on the Aβ plaque load (p = 0.39), the number and size of plaques, or the Aβ plaque-induced increases in microglial numbers in the dentate gyrus. Three months of serotonin depletion did not significantly impact the Aβ plaque load or Aβ 42/Aβ 40 ratio in APPswe/PS1 ΔE9 mice at 12 months. CONCLUSION Our results show that chronic treatment with the SSRI paroxetine does not mitigate Aβ pathology and Aβ plaque-induced microgliosis in the hippocampus of APPswe/PS1 ΔE9 mice.
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Affiliation(s)
- Mithula Sivasaravanaparan
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Maurizio Severino
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Kate Lykke Lambertsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Neurology, Odense University Hospital, Odense, Denmark.,Department of Clinical Research, BRIDGE-Brain Research-Inter-Disciplinary Guided Excellence, University of Southern Denmark, Denmark
| | - Jan Bert Gramsbergen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark
| | | | - Athanasios Metaxas
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Life Sciences, School of Science, European University Cyprus, Nicosia, Cyprus
| | - Ove Wiborg
- Department of Clinical Medicine, Aarhus University Hospital, Denmark.,Department of Health Science and Technology, Aalborg University, Denmark
| | - Bente Finsen
- Department of Neurobiology, Institute of Molecular Medicine, University of Southern Denmark, Denmark.,Department of Clinical Research, BRIDGE-Brain Research-Inter-Disciplinary Guided Excellence, University of Southern Denmark, Denmark
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14
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Aaldijk E, Vermeiren Y. The role of serotonin within the microbiota-gut-brain axis in the development of Alzheimer's disease: A narrative review. Ageing Res Rev 2022; 75:101556. [PMID: 34990844 DOI: 10.1016/j.arr.2021.101556] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/20/2021] [Accepted: 12/30/2021] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia, accounting for more than 50 million patients worldwide. Current evidence suggests the exact mechanism behind this devastating disease to be of multifactorial origin, which seriously complicates the quest for an effective disease-modifying therapy, as well as impedes the search for strategic preventative measures. Of interest, preclinical studies point to serotonergic alterations, either induced via selective serotonin reuptake inhibitors or serotonin receptor (ant)agonists, in mitigating AD brain neuropathology next to its clinical symptoms, the latter being supported by a handful of human intervention trials. Additionally, a substantial amount of preclinical trials highlight the potential of diet, fecal microbiota transplantations, as well as pre- and probiotics in modulating the brain's serotonergic neurotransmitter system, starting from the gut. Whether such interventions could truly prevent, reverse or slow down AD progression likewise, should be initially tested in preclinical studies with AD mouse models, including sufficient analytical measurements both in gut and brain. Thereafter, its potential therapeutic effect could be confirmed in rigorously randomized controlled trials in humans, preferentially across the Alzheimer's continuum, but especially from the prodromal up to the mild stages, where both high adherence to such therapies, as well as sufficient room for noticeable enhancement are feasible still. In the end, such studies might aid in the development of a comprehensive approach to tackle this complex multifactorial disease, since serotonin and its derivatives across the microbiota-gut-brain axis might serve as possible biomarkers of disease progression, next to forming a valuable target in AD drug development. In this narrative review, the available evidence concerning the orchestrating role of serotonin within the microbiota-gut-brain axis in the development of AD is summarized and discussed, and general considerations for future studies are highlighted.
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Affiliation(s)
- Emma Aaldijk
- Division of Human Nutrition and Health, Chair Group of Nutritional Biology, Wageningen University & Research (WUR), Wageningen, Netherlands
| | - Yannick Vermeiren
- Division of Human Nutrition and Health, Chair Group of Nutritional Biology, Wageningen University & Research (WUR), Wageningen, Netherlands; Faculty of Medicine & Health Sciences, Translational Neurosciences, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium.
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15
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Psychosis in Alzheimer disease - mechanisms, genetics and therapeutic opportunities. Nat Rev Neurol 2022; 18:131-144. [PMID: 34983978 PMCID: PMC9074132 DOI: 10.1038/s41582-021-00597-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2021] [Indexed: 12/14/2022]
Abstract
Psychosis is a common and distressing symptom in people with Alzheimer disease, and few safe and effective treatments are available. However, new approaches to symptom assessment and treatment are beginning to drive the field forward. New nosological perspectives have been provided by incorporating the emergence of psychotic symptoms in older adults - even in advance of dementia - into epidemiological and neurobiological frameworks as well as into diagnostic and research criteria such as the International Psychogeriatric Association criteria for psychosis in neurocognitive disorders, the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART) research criteria for psychosis in neurodegenerative disease, and the ISTAART criteria for mild behavioural impairment. Here, we highlight the latest findings in genomics, neuroimaging and neurobiology that are informing approaches to drug discovery and repurposing. Current pharmacological and non-pharmacological treatment options are discussed, with a focus on safety and precision medicine. We also explore trial data for pimavanserin, a novel agent that shows promise for the treatment of psychosis in people with dementia, and discuss existing agents that might be useful but need further exploration such as escitalopram, lithium, cholinesterase inhibitors and vitamin D. Although the assessment and management of psychosis in people with dementia remain challenging, new opportunities are providing direction and hope to the field.
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16
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How nano-engineered delivery systems can help marketed and repurposed drugs in Alzheimer’s disease treatment? Drug Discov Today 2022; 27:1575-1589. [DOI: 10.1016/j.drudis.2022.02.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/11/2022] [Accepted: 02/22/2022] [Indexed: 11/24/2022]
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17
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Cutuli D, Giacovazzo G, Decandia D, Coccurello R. Alzheimer's disease and depression in the elderly: A trajectory linking gut microbiota and serotonin signaling. Front Psychiatry 2022; 13:1010169. [PMID: 36532180 PMCID: PMC9750201 DOI: 10.3389/fpsyt.2022.1010169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/28/2022] [Indexed: 12/05/2022] Open
Abstract
The occurrence of neuropsychiatric symptoms in the elderly is viewed as an early sign of subsequent cognitive deterioration and conversion from mild cognitive impairment to Alzheimer's disease. The prognosis in terms of both the severity and progression of clinical dementia is generally aggravated by the comorbidity of neuropsychiatric symptoms and decline in cognitive function. Undeniably, aging and in particular unhealthy aging, is a silent "engine of neuropathology" over which multiple changes take place, including drastic alterations of the gut microbial ecosystem. This narrative review evaluates the role of gut microbiota changes as a possible unifying concept through which the comorbidity of neuropsychiatric symptoms and Alzheimer's disease can be considered. However, since the heterogeneity of neuropsychiatric symptoms, it is improbable to describe the same type of alterations in the bacteria population observed in patients with Alzheimer's disease, as well as it is improbable that the variety of drugs used to treat neuropsychiatric symptoms might produce changes in gut bacterial diversity similar to that observed in the pathophysiology of Alzheimer's disease. Depression seems to be another very intriguing exception, as it is one of the most frequent neuropsychiatric symptoms in dementia and a mood disorder frequently associated with brain aging. Antidepressants (i.e., serotonin reuptake inhibitors) or tryptophan dietary supplementation have been shown to reduce Amyloid β-loading, reinstate microbial diversity and reduce the abundance of bacterial taxa dominant in depression and Alzheimer's disease. This review briefly examines this trajectory by discussing the dysfunction of gut microbiota composition, selected bacterial taxa, and alteration of tryptophan and serotonin metabolism/neurotransmission as overlapping in-common mechanisms involved with depression, Alzheimer's disease, and unhealthy aging.
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Affiliation(s)
- Debora Cutuli
- Department of Psychology, University of Rome La Sapienza, Rome, Italy.,European Center for Brain Research, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Giacomo Giacovazzo
- European Center for Brain Research, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Davide Decandia
- Department of Psychology, University of Rome La Sapienza, Rome, Italy.,European Center for Brain Research, Santa Lucia Foundation IRCCS, Rome, Italy
| | - Roberto Coccurello
- European Center for Brain Research, Santa Lucia Foundation IRCCS, Rome, Italy.,Institute for Complex Systems (ISC), National Council of Research (CNR), Rome, Italy
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18
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Nykamp MJ, Zorumski CF, Reiersen AM, Nicol GE, Cirrito J, Lenze EJ. Opportunities for Drug Repurposing of Serotonin Reuptake Inhibitors: Potential Uses in Inflammation, Infection, Cancer, Neuroprotection, and Alzheimer's Disease Prevention. PHARMACOPSYCHIATRY 2021; 55:24-29. [PMID: 34875696 DOI: 10.1055/a-1686-9620] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Serotonin reuptake inhibitors (SRIs) are safe and widely used for a variety of indications including depressive disorders, anxiety, and chronic pain. Besides inhibiting the serotonin transporter, these medications have broad-spectrum properties in many systems. Their roles have been studied in cancer, Alzheimer's disease, and infectious processes. The COVID-19 pandemic highlighted the importance of drug repurposing of medications already in use. We conducted a narrative review of current evidence and ongoing research on drug repurposing of SRIs, with a focus on immunomodulatory, antiproliferative, and neuroprotective activity. SRIs may have clinical use as repurposed agents for a wide variety of conditions including but not limited to COVID-19, Alzheimer's disease, and neoplastic processes. Further research, particularly randomized controlled trials, will be necessary to confirm the utility of SRIs for new indications.
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Affiliation(s)
- Madeline J Nykamp
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Charles F Zorumski
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Angela M Reiersen
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Ginger E Nicol
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - John Cirrito
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Eric J Lenze
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
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19
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Alzheimer's disease clinical trial update 2019-2021. J Neurol 2021; 269:1038-1051. [PMID: 34609602 DOI: 10.1007/s00415-021-10790-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 12/12/2022]
Abstract
The current clinical trial landscape targeting Alzheimer's disease (AD) is reviewed in the context of studies completed from 2019 to 2021. This review focuses on available data for observational and phase II/III clinical trial results, which will have the most impact on the field. ClinicalTrials.gov, the United States (US) comprehensive federal registry, was queried to identify completed trials. There are currently 226 interventional clinical trials and 51 observational studies completed, suspended, terminated, or withdrawn within our selected time frame. This review reveals that the role of biomarkers is expanding and although many lessons have been learned, many challenges remain when targeting disease modification of AD through amyloid and tau. In addition, to halt or slow clinical progression of AD, new clinical and observational trials are focusing on prevention as well as the role of more diverse biological processes known to influence AD pathology.
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20
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Smith GS, Workman CI, Protas H, Su Y, Savonenko A, Kuwabara H, Gould NF, Kraut M, Joo JH, Nandi A, Avramopoulos D, Reiman EM, Chen K. Positron emission tomography imaging of serotonin degeneration and beta-amyloid deposition in late-life depression evaluated with multi-modal partial least squares. Transl Psychiatry 2021; 11:473. [PMID: 34518514 PMCID: PMC8437937 DOI: 10.1038/s41398-021-01539-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/13/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022] Open
Abstract
Depression in late-life is associated with increased risk of cognitive decline and development of all-cause dementia. The neurobiology of late-life depression (LLD) may involve both neurochemical and neurodegenerative mechanisms that are common to depression and dementia. Transgenic amyloid mouse models show evidence of early degeneration of monoamine systems. Informed by these preclinical data, the hypotheses were tested that a spatial covariance pattern of higher beta-amyloid (Aβ) and lower serotonin transporter availability (5-HTT) in frontal, temporal, and parietal cortical regions would distinguish LLD patients from healthy controls and the expression of this pattern would be associated with greater depressive symptoms. Twenty un-medicated LLD patients who met DSM-V criteria for major depression and 20 healthy controls underwent PET imaging with radiotracers for Aβ ([11C]-PiB) and 5-HTT ([11C]-DASB). A voxel-based multi-modal partial least squares (mmPLS) algorithm was applied to the parametric PET images to determine the spatial covariance pattern between the two radiotracers. A spatial covariance pattern was identified, including higher Aβ in temporal, parietal and occipital cortices associated with lower 5-HTT in putamen, thalamus, amygdala, hippocampus and raphe nuclei (dorsal, medial and pontine), which distinguished LLD patients from controls. Greater expression of this pattern, reflected in summary 5-HTT/Aβ mmPLS subject scores, was associated with higher levels of depressive symptoms. The mmPLS method is a powerful approach to evaluate the synaptic changes associated with AD pathology. This spatial covariance pattern should be evaluated further to determine whether it represents a biological marker of antidepressant treatment response and/or cognitive decline in LLD patients.
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Affiliation(s)
- Gwenn S Smith
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Clifford I Workman
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Yi Su
- Banner Alzheimer's Institute, Phoenix, AZ, USA
| | - Alena Savonenko
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hiroto Kuwabara
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neda F Gould
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael Kraut
- Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jin Hui Joo
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ayon Nandi
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dimitri Avramopoulos
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Kewei Chen
- Banner Alzheimer's Institute, Phoenix, AZ, USA
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21
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Reddy AP, Yin X, Sawant N, Reddy PH. Protective effects of antidepressant citalopram against abnormal APP processing and amyloid beta-induced mitochondrial dynamics, biogenesis, mitophagy and synaptic toxicities in Alzheimer's disease. Hum Mol Genet 2021; 30:847-864. [PMID: 33615359 PMCID: PMC8355469 DOI: 10.1093/hmg/ddab054] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 01/24/2021] [Accepted: 02/12/2021] [Indexed: 12/14/2022] Open
Abstract
The purpose of this study is to study the neuroprotective role of selective serotonin reuptake inhibitor (SSRI), citalopram, against Alzheimer's disease (AD). Multiple SSRIs, including citalopram, are reported to treat patients with depression, anxiety and AD. However, their protective cellular mechanisms have not been studied completely. In the current study, we investigated the protective role of citalopram against impaired mitochondrial dynamics, defective mitochondrial biogenesis, defective mitophagy and synaptic dysfunction in immortalized mouse primary hippocampal cells (HT22) expressing mutant APP (SWI/IND) mutations. Using quantitative RT-PCR, immunoblotting, biochemical methods and transmission electron microscopy methods, we assessed mutant full-length APP/C-terminal fragments and Aβ levels and mRNA and protein levels of mitochondrial dynamics, biogenesis, mitophagy and synaptic genes in mAPP-HT22 cells and mAPP-HT22 cells treated with citalopram. Increased levels of mRNA levels of mitochondrial fission genes, decreased levels of fusion biogenesis, autophagy, mitophagy and synaptic genes were found in mAPP-HT22 cells relative to WT-HT22 cells. However, mAPP-HT22 cells treated with citalopram compared to mAPP-HT22 cells revealed reduced levels of the mitochondrial fission genes, increased fusion, biogenesis, autophagy, mitophagy and synaptic genes. Our protein data agree with mRNA levels. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in mAPP-HT22 cells; these were reversed in citalopram-treated mAPP-HT22 cells. Cell survival rates were increased in citalopram-treated mAPP-HT22 relative to citalopram-untreated mAPP-HT22. Further, mAPP and C-terminal fragments werealso reduced in citalopram-treated cells. These findings suggest that citalopram reduces mutant APP and Aβ and mitochondrial toxicities and may have a protective role of mutant APP and Aβ-induced injuries in patients with depression, anxiety and AD.
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Affiliation(s)
- Arubala P Reddy
- Nutritional Sciences Department, Texas Tech University, Lubbock, TX, USA
| | - Xiangling Yin
- Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Neha Sawant
- Internal Medicine Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - P Hemachandra Reddy
- Internal Medicine Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Pharmacology & Neuroscience Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Neurology Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Speech, Language and Hearing Sciences Departments, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Public Health Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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22
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Miziak B, Błaszczyk B, Czuczwar SJ. Some Candidate Drugs for Pharmacotherapy of Alzheimer's Disease. PHARMACEUTICALS (BASEL, SWITZERLAND) 2021; 14:ph14050458. [PMID: 34068096 PMCID: PMC8152728 DOI: 10.3390/ph14050458] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 12/12/2022]
Abstract
Alzheimer’s disease (AD; progressive neurodegenerative disorder) is associated with cognitive and functional impairment with accompanying neuropsychiatric symptoms. The available pharmacological treatment is of a symptomatic nature and, as such, it does not modify the cause of AD. The currently used drugs to enhance cognition include an N-methyl-d-aspartate receptor antagonist (memantine) and cholinesterase inhibitors. The PUBMED, Medical Subject Heading and Clinical Trials databases were used for searching relevant data. Novel treatments are focused on already approved drugs for other conditions and also searching for innovative drugs encompassing investigational compounds. Among the approved drugs, we investigated, are intranasal insulin (and other antidiabetic drugs: liraglitude, pioglitazone and metformin), bexarotene (an anti-cancer drug and a retinoid X receptor agonist) or antidepressant drugs (citalopram, escitalopram, sertraline, mirtazapine). The latter, especially when combined with antipsychotics (for instance quetiapine or risperidone), were shown to reduce neuropsychiatric symptoms in AD patients. The former enhanced cognition. Procognitive effects may be also expected with dietary antioxidative and anti-inflammatory supplements—curcumin, myricetin, and resveratrol. Considering a close relationship between brain ischemia and AD, they may also reduce post-brain ischemia neurodegeneration. An investigational compound, CN-105 (a lipoprotein E agonist), has a very good profile in AD preclinical studies, and its clinical trial for postoperative dementia is starting soon.
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Affiliation(s)
- Barbara Miziak
- Department of Pathophysiology, Medical University of Lublin, 20-090 Lublin, Poland;
| | - Barbara Błaszczyk
- Faculty of Health Sciences, High School of Economics, Law and Medical Sciences, 25-734 Kielce, Poland;
| | - Stanisław J. Czuczwar
- Department of Pathophysiology, Medical University of Lublin, 20-090 Lublin, Poland;
- Correspondence: ; Tel.: +48-81-448-65-00; Fax: +48-81-65-00-01
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23
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Gatchel JR. Late-Life Depression and Alzheimer's Disease Pathology: An Ounce of Prevention, a Pound of Cure. Am J Geriatr Psychiatry 2021; 29:458-461. [PMID: 33293249 DOI: 10.1016/j.jagp.2020.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 11/18/2022]
Affiliation(s)
- Jennifer R Gatchel
- Department of Psychiatry, Massachusetts General Hospital, Boston MA; Division of Geriatric Psychiatry, McLean Hospital; Harvard Medical School, Boston MA, USA.
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24
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Ng KP, Chiew H, Rosa-Neto P, Kandiah N, Ismail Z, Gauthier S. Associations of AT(N) biomarkers with neuropsychiatric symptoms in preclinical Alzheimer's disease and cognitively unimpaired individuals. Transl Neurodegener 2021; 10:11. [PMID: 33789730 PMCID: PMC8011383 DOI: 10.1186/s40035-021-00236-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/09/2021] [Indexed: 12/12/2022] Open
Abstract
The development of in vivo biomarkers of Alzheimer's disease (AD) has advanced the diagnosis of AD from a clinical syndrome to a biological construct. The preclinical stage of AD continuum is defined by the identification of AD biomarkers crossing the pathological threshold in cognitively unimpaired individuals. While neuropsychiatric symptoms (NPS) are non-cognitive symptoms that are increasingly recognized as early manifestations of AD, the associations of NPS with AD pathophysiology in preclinical AD remain unclear. Here, we review the associations between NPS and AD biomarkers amyloid-β (Aβ), tau and neurodegeneration in preclinical AD and cognitively-unimpaired individuals in 19 eligible English-language publications (8 cross-sectional studies, 10 longitudinal, 1 both cross-sectional and longitudinal). The cross-sectional studies have consistently shown that NPS, particularly depressive and anxiety symptoms, are associated with higher Aβ. The longitudinal studies have suggested that greater NPS are associated with higher Aβ and cognitive decline in cognitively unimpaired subjects over time. However, most of the studies have either cross-sectionally or longitudinally shown no association between NPS and tau pathology. For the association of NPS and neurodegeneration, two studies have shown that the cerebrospinal fluid total-tau is linked to longitudinal increase in NPS and that the NPS may predict longitudinal metabolic decline in preclinical AD, respectively. However, evidence for the association between atrophy and NPS in preclinical AD is less consistent. Therefore, future longitudinal studies with well-designed methodologies and NPS measurements are required not only to determine the relationship among AT(N) biomarkers, NPS and cognitive decline, but also to elucidate the contribution of comorbid pathology to preclinical AD.
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Affiliation(s)
- Kok Pin Ng
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Medical School, Singapore, Singapore
- Lee Kong Chian School of Medicine - Imperial College London, Nanyang Technological University, Singapore, Singapore
| | - Hui Chiew
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Medical School, Singapore, Singapore
- Lee Kong Chian School of Medicine - Imperial College London, Nanyang Technological University, Singapore, Singapore
| | - Pedro Rosa-Neto
- The McGill University Research Centre for Studies in Aging, Montreal, Canada
| | - Nagaendran Kandiah
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Medical School, Singapore, Singapore
- Lee Kong Chian School of Medicine - Imperial College London, Nanyang Technological University, Singapore, Singapore
| | - Zahinoor Ismail
- Hotchkiss Brain Institute and O'Brien Institute for Public Health; Departments of Psychiatry, Clinical Neurosciences, and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Serge Gauthier
- The McGill University Research Centre for Studies in Aging, Montreal, Canada.
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25
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26
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Cirrito JR, Wallace CE, Yan P, Davis TA, Gardiner WD, Doherty BM, King D, Yuede CM, Lee JM, Sheline YI. Effect of escitalopram on Aβ levels and plaque load in an Alzheimer mouse model. Neurology 2020; 95:e2666-e2674. [PMID: 32913022 PMCID: PMC7713734 DOI: 10.1212/wnl.0000000000010733] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 06/12/2020] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Several neurotransmitter receptors activate signaling pathways that alter processing of the amyloid precursor protein (APP) into β-amyloid (Aβ). Serotonin signaling through a subset of serotonin receptors suppresses Aβ generation. We proposed that escitalopram, the most specific selective serotonin reuptake inhibitor (SSRI) that inhibits the serotonin transporter SERT, would suppress Aβ levels in mice. OBJECTIVES We hypothesized that acute treatment with escitalopram would reduce Aβ generation, which would be reflected chronically with a significant reduction in Aβ plaque load. METHODS We performed in vivo microdialysis and in vivo 2-photon imaging to assess changes in brain interstitial fluid (ISF) Aβ and Aβ plaque size over time, respectively, in the APP/presenilin 1 mouse model of Alzheimer disease treated with vehicle or escitalopram. We also chronically treated mice with escitalopram to determine the effect on plaques histologically. RESULTS Escitalopram acutely reduced ISF Aβ by 25% by increasing α-secretase cleavage of APP. Chronic administration of escitalopram significantly reduced plaque load by 28% and 34% at 2.5 and 5 mg/d, respectively. Escitalopram at 5 mg/kg did not remove existing plaques, but completely arrested individual plaque growth over time. CONCLUSIONS Escitalopram significantly reduced Aβ in mice, similar to previous findings in humans treated with acute dosing of an SSRI.
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Affiliation(s)
- John R Cirrito
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia.
| | - Clare E Wallace
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Ping Yan
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Todd A Davis
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Woodrow D Gardiner
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Brookelyn M Doherty
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Diana King
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Carla M Yuede
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Jin-Moo Lee
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
| | - Yvette I Sheline
- From the Department of Neurology (J.R.C., T.A.D., W.D.G., B.M.D., D.K., C.M.Y., J.-M.L.), The Knight Alzheimer's Disease Research Center, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO; Center for Neuromodulation in Depression and Stress, Department of Psychiatry (C.E.W., P.Y., Y.I.S.), and Departments of Psychiatry, Radiology, and Neurology (Y.I.S.), University of Pennsylvania, Philadelphia
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