Who seeks genetic susceptibility testing for Alzheimer's disease? Findings from a multisite, randomized clinical trial

Purpose: Alzheimer's disease, for which one form of the apolipoprotein E (APOE) genotype is a risk factor, provides a paradigm in which to examine response to susceptibility testing for common, complex diseases. This study's main purposes were to estimate interest in such testing and to examine demographic predictors of study participation. Methods: In this 3-site, randomized clinical trial (RCT), the intervention was a risk assessment program wherein genetic counselors educated adult children of AD patients about lifetime risk of disease based on their gender, family history, and APOE genotype. Two groups of participants were followed from initial contact to RCT enrollment: those who were systematically contacted through research registries, and those who were self-referred. Results: Of 196 systematically contacted participants, 47, or 24%, progressed from initial contact to RCT enrollment. These participants were more likely to be below age 60 (adjusted OR = 3.83, P < 0.01) and college educated (adjusted OR = 3.48, P < 0.01). Of 179 self-referred participants, 115, or 64%, progressed from initial contact to RCT enrollment. Most self-referred participants had a college education and were female (79%). Conclusions: In the first RCT to examine genetic susceptibility testing for AD, uptake rates were sufficiently high to merit concern that future test demand may strain available education and counseling resources. Findings suggest that susceptibility testing for AD may be of particular interest to women, college educated persons, and persons below age 60.