Brain-imaging surrogate markers for detection and prevention of age-related memory loss.
Recent evidence points to the importance of neuropathological and cognitive changes preceding Alzheimer's disease (AD), and clinical trials have begun to focus on preventive treatments designed to slow age-related cognitive decline and delay the onset of AD in people with age-associated memory impairment (AAMI). Studying subjects with few deficits leads to diagnostic heterogeneity and a need for larger samples in order to detect active drug effects. In this report, I review results of recent studies designed to address such issues. Middle-aged and older adults with mild memory complaints were studied using brain imaging and measures of the major known genetic risk for AD, the apolipoprotein E-4 (APOE-4) allele. In a study of positron emission tomography during mental rest, glucose metabolic rates were significantly lower in APOE-4 carriers in brain regions affected by AD. Another study using functional magnetic resonance imaging showed increased brain activation during memory tasks in APOE-4 carriers in similar brain regions. Longitudinal follow-up after 2 yr indicated the potential utility of such brain-imaging measures, combined with genetic-risk information, as surrogate markers in treatment trials for AAMI to prevent further cognitive decline. Current development focuses on novel technologies using positron emission tomography to directly image the neuritic plaques and neurofibrillary tangles of AD in order to provide more specific measures of disease progression in future clinical trials.
Small
Gary W
GW
Department of Psychiatry and Biobehavioral Sciences and the Center on Aging, University of California, Los Angeles School of Medicine, USA. gsmall@mednet.ucla.edu
D000375:Aging; D000544:Alzheimer Disease / Q000175:diagnosis / Q000517:prevention & control; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000378:metabolism* / Q000473:pathology*; D003952:Diagnostic Imaging / Q000379:methods* / Q000639:trends; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D008279:Magnetic Resonance Imaging; D008569:Memory Disorders / Q000175:diagnosis* / Q000235:genetics / Q000517:prevention & control*; D016874:Neurofibrillary Tangles / Q000378:metabolism / Q000473:pathology; D058225:Plaque, Amyloid / Q000378:metabolism / Q000473:pathology; D011237:Predictive Value of Tests; D012307:Risk Factors; D014055:Tomography, Emission-Computed
D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D015415:Biomarkers