Alzheimer disease (AD) is a progressive, ultimately fatal neurodegenerative illness affecting millions of patients, families, and caregivers. Effective disease-modifying therapies for AD are desperately needed, but none currently exist on the market. Thus, accelerating the discovery, development, and approval of new disease-modifying drugs for AD is a high priority for individuals, physicians, and medical decision makers. Potentially disease-modifying drugs likely will have significant therapeutic benefits but also may have treatment-related risks. We quantified older Americans' treatment-related risk tolerance by eliciting their willingness to accept the risk of treatment-related death or permanent severe disability in exchange for modifying the course of AD. A stated-choice survey instrument was administered to 2146 American residents 60 years of age and older. On average, subjects were willing to accept a 1-year risk of treatment-related death or permanent severe disability from stroke of over 30% for a treatment that prevents AD from progressing beyond the mild stage. Thus, most people in this age cohort are willing to accept considerable risks in return for disease-modifying benefits of new AD drugs. These results are consistent with other studies indicating that individuals view AD as a serious, life threatening illness that imposes heavy burdens on both patients and caregivers.