ABSTRACT
Alzheimer’s disease (AD) is a major public health issue largely because of the life expectancy of the US population. The development of a biological marker capable of distinguishing patients with AD with extremely high specificity and sensitivity would be quite useful. The variability introduces significant variance in trials of agents designed to slow the rate of progression in AD and dictates the use of large sample sizes to detect significant differences. In addition to memory impairment, patients with AD have a wide variety of cognitive and behavioral impairments. In most clinical series, diagnostic accuracy is about 85% for clinical research purposes such as clinical drug trials. The high degree of variability in rate of decline complicates the detection of small differences in rate of decline in clinical drug trials. The types of trial designs used to test drugs in AD patients have undergone considerable modification and change.
