CONCLUSIONS
An effective treatment for sporadic Alzheimer's disease rests on the translation of the disease pathways we have discussed, as well as additional molecular mechanisms or new risk genes (e.g., apolipoprotein J) defined by gene-expression profiling and whole-genome association studies,181,182 into specific pharmacologic targets. Examples of recently discovered proteins encoded by these risk genes and mechanisms include apolipoprotein J (clusterin), another Aβ chaperone,183 TOMM40, a transporter of proteins across the mitochondrial membrane, and Sortillin-related receptor, which functions to partition amyloid precursor protein away from β-secretase and γ-secretase; this is consistent with observations that levels are reduced in the brains of patients with Alzheimer's disease and mild cognitive impairment.184,185 Another potential risk factor for sporadic Alzheimer's disease, general anesthesia, promotes tau insolubility and Aβ oligomerization,186,187 deficiency of estrogen in the brains of postmenopausal women,188 and chronic activation of the glucocorticoid axis.189 However, their underlying mechanisms are diverse, and whether any of these factors lead to amyloid deposition and tauopathy in humans is unknown. Prospective studies also show that cognitive leisure activity and training can lower the risk of dementia190; findings from these studies provide support for the concept of building a “cognitive reserve.” The figure in the Supplementary Appendix (available with the full text of this article at NEJM.org) summarizes the heterogeneity of pathways that could initiate and drive Alzheimer's disease. There is no single linear chain of events. Complicating matters, some changes are not pathologic but reactionary or protective. Thus, the development of a multitargeted approach to prevent or symptomatically treat Alzheimer's disease, as used in current practice for other multigenic disorders, is needed.191 Recent studies point to brain atrophy and other pathologic conditions, not severe amyloid or tangle load, in accounting for dementia in the oldest old (persons 80 years of age or older).192 It remains possible that many of these mechanisms, including the amyloid hypothesis, are minor or wrong and that some critical aging-related process is the disease trigger.
บทสรุปAn effective treatment for sporadic Alzheimer's disease rests on the translation of the disease pathways we have discussed, as well as additional molecular mechanisms or new risk genes (e.g., apolipoprotein J) defined by gene-expression profiling and whole-genome association studies,181,182 into specific pharmacologic targets. Examples of recently discovered proteins encoded by these risk genes and mechanisms include apolipoprotein J (clusterin), another Aβ chaperone,183 TOMM40, a transporter of proteins across the mitochondrial membrane, and Sortillin-related receptor, which functions to partition amyloid precursor protein away from β-secretase and γ-secretase; this is consistent with observations that levels are reduced in the brains of patients with Alzheimer's disease and mild cognitive impairment.184,185 Another potential risk factor for sporadic Alzheimer's disease, general anesthesia, promotes tau insolubility and Aβ oligomerization,186,187 deficiency of estrogen in the brains of postmenopausal women,188 and chronic activation of the glucocorticoid axis.189 However, their underlying mechanisms are diverse, and whether any of these factors lead to amyloid deposition and tauopathy in humans is unknown. Prospective studies also show that cognitive leisure activity and training can lower the risk of dementia190; findings from these studies provide support for the concept of building a “cognitive reserve.” The figure in the Supplementary Appendix (available with the full text of this article at NEJM.org) summarizes the heterogeneity of pathways that could initiate and drive Alzheimer's disease. There is no single linear chain of events. Complicating matters, some changes are not pathologic but reactionary or protective. Thus, the development of a multitargeted approach to prevent or symptomatically treat Alzheimer's disease, as used in current practice for other multigenic disorders, is needed.191 Recent studies point to brain atrophy and other pathologic conditions, not severe amyloid or tangle load, in accounting for dementia in the oldest old (persons 80 years of age or older).192 It remains possible that many of these mechanisms, including the amyloid hypothesis, are minor or wrong and that some critical aging-related process is the disease trigger.
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