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Roussotte FF, Gutman BA, Hibar DP, Madsen SK, Narr KL, Thompson PM. Carriers of a common variant in the dopamine transporter gene have greater dementia risk, cognitive decline, and faster ventricular expansion. Alzheimers Dement 2015; 11:1153-62. [PMID: 25496873 PMCID: PMC4465053 DOI: 10.1016/j.jalz.2014.10.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 07/19/2014] [Accepted: 10/27/2014] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Genetic variants in DAT1, the gene encoding the dopamine transporter (DAT) protein, have been implicated in many brain disorders. In a recent case-control study of Alzheimer's disease (AD), a regulatory polymorphism in DAT1 showed a significant association with the clinical stages of dementia. METHODS We tested whether this variant was associated with increased AD risk, and with measures of cognitive decline and longitudinal ventricular expansion, in a large sample of elderly participants with genetic, neurocognitive, and neuroimaging data from the Alzheimer's Disease Neuroimaging Initiative. RESULTS The minor allele-previously linked with increased DAT expression in vitro-was more common in AD patients than in both individuals with mild cognitive impairment and healthy elderly controls. The same allele was also associated with poorer cognitive performance and faster ventricular expansion, independently of diagnosis. DISCUSSION These results may be due to reduced dopaminergic transmission in carriers of the DAT1 mutation.
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Affiliation(s)
- Florence F Roussotte
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Boris A Gutman
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Derrek P Hibar
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Sarah K Madsen
- Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Katherine L Narr
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Paul M Thompson
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Imaging Genetics Center, Institute for Neuroimaging and Informatics, Department of Neurology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA; Department of Psychiatry, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Departments of Psychiatry, Engineering, Radiology, & Ophthalmology, Keck/USC School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Ono K, Takasaki JI, Takahashi R, Ikeda T, Yamada M. Effects of antiparkinsonian agents on β-amyloid and α-synuclein oligomer formation in vitro. J Neurosci Res 2013; 91:1371-81. [PMID: 23913715 DOI: 10.1002/jnr.23256] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 05/14/2013] [Indexed: 01/08/2023]
Abstract
The aggregation of β-amyloid protein (Aβ) and α-synuclein (αS) are hypothesized to be the key pathogenic event in Alzheimer's disease (AD) and Lewy body diseases (LBD), with oligomeric assemblies thought to be the most neurotoxic. Inhibitors of oligomer formation, therefore, could be valuable therapeutics for patients with AD and LBD. Here, we examined the effects of antiparkinsonian agents (dopamine, levodopa, trihexyphenidyl, selegiline, zonisamide, bromocriptine, peroxide, ropinirole, pramipexole, and entacapone) on the in vitro oligomer formation of Aβ40, Aβ42, and αS using a method of photo-induced cross-linking of unmodified proteins (PICUP), electron microscopy, and atomic force microscopy. The antiparkinsonian agents except for trihexyphenidyl inhibited both Aβ and αS oligomer formations, and, among them, dopamine, levodopa, pramipexole, and entacapone had the stronger in vitro activity. Circular dichroism and thioflavin T(S) assays showed that secondary structures of Aβ and αS assemblies inhibited by antiparkinsonian agents were statistical coil state and that their seeding activities had disappeared. The antiparkinsonian agents could be potential therapeutic agents to prevent or delay AD and LBD progression.
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Affiliation(s)
- Kenjiro Ono
- Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
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Novel insights for the treatment of Alzheimer's disease. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:373-9. [PMID: 20655969 DOI: 10.1016/j.pnpbp.2010.07.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 07/02/2010] [Accepted: 07/15/2010] [Indexed: 12/12/2022]
Abstract
The development of treatments for Alzheimer's disease (AD) is currently shifting away from the correction of neurotransmitter abnormalities and from attempts to remove the pathognomonic protein deposits. Drug discovery is heading towards novel types of pharmacological interventions which are aimed at more central and upstream pathophysiological events. The large number of upcoming treatment targets can be grouped into two major categories. The first category consists of antecedents of beta amyloid peptide (Aβ) and TAU deposition including Aβ production, degradation and clearance, TAU hyperphosphorylation and aggregation. The second consists of protectors against neuronal dysfunction and premature death such as mitochondrial functioning, nerve growth and regeneration, and neuronal membrane integrity. It is hoped that some of these strategies will not only have larger symptomatic effects than the currently available drugs but also an impact on the underlying neurodegeneration. Since the novel treatments will be typically administered over years they must meet high standards of safety, drug-drug compatibility, and tolerability. Probably the most important target groups for novel treatments are carriers of mutations causing AD, and individuals with minor cognitive impairment representing a pre-dementia stage of the disease. To minimise incorrect case identifications, drug development must be paralleled by improved diagnostic techniques. Novel pharmacological strategies may be cost-effective if disability and need of full-time care can be postponed or prevented without prolonging time lived with dementia or extending survival. We are uncertain whether the advent of novel disease-retarding strategies will revolutionise the management of AD. Symptomatic treatments will continue to be needed, and psychosocial approaches will retain an essential role in supporting affected individuals and their families.
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