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F3‐04‐03: The Alzheimer's Prevention Initiative
Author(s) -
Reiman Eric,
Lopera Francisco,
Langbaum Jessica,
Fleisher Adam,
Ayutyat Napatkamon,
Quiroz Yakeel,
Jakimovich Laura,
Langlois Carolyn,
Tariot Pierre
Publication year - 2012
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2012.05.1136
Subject(s) - medicine , biomarker , clinical trial , disease , alzheimer's disease , oncology , genetic testing , genetics , biology
genic animal experiments suggest that we may be testing anti-Ab therapies much too late in the pathophysiological process of Alzheimer’s disease (AD). Converging data from PETamyloid imaging, cerebrospinal fluid studies, and large autopsy series suggest that approximately one-third of clinically normal older individuals harbor a substantial burden of cerebral amyloid-b. These amyloid-positive “normals” demonstrate evidence of functional and structural imaging abnormalities, elevation of CSF tau, and subtle cognitive deficits, consistent with the preclinical stages of AD, and represent an ideal population for a large secondary prevention effort to slow cognitive decline. Methods: The Alzheimer’s Disease Cooperative Study (ADCS) is proposing a placebo-controlled, 3-year trial in clinically normal older individuals with biomarker evidence of AD pathology. The primary outcome will be slowing the rate of decline on a cognitive composite, with multiple biomarkers as secondary outcomes. Eligible subjects will be clinically normal (CDR 0, MMSE 27-30), over age 70, and will have evidence of amyloid-positivity on PET amyloid imaging. The choice of treatment has not yet been finalized, but will be a monoclonal antibody with clear evidence of target engagement and adequate safety data to support a 3-year trial.Results:Analyses using available data from the Alzheimer’s Disease Neuroimaging Initiative and Australian Imaging Biomarkers Lifestyle study consistently demonstrate evidence of an increased rate of cognitive decline in amyloid-positive normals, and that approximately n1⁄4500 subjects per arm will yield adequate power to detect a 25-35% treatment-related decrease in the rate of cognitive decline. We will also include a natural history arm of 500 amyloid-negative individuals to investigate the specific pattern of “amyloid-related” decline and to develop more sensitive outcome measures to improve the efficiency of future secondary prevention trials in preclinical AD.Conclusions:TheA4 trial will provide complementary information to the prevention initiatives being planned in genetic-risk cohorts. Although amyloid-b may be only one of several pathogenic factors in the elderly population, we now have the biomarker tools and biologically active compounds to test the hypothesis that altering “upstream” amyloid burden will impact “downstream” neurodegeneration and delay or prevent cognitive decline.