However, because patients with early Alzheimer's disease have little-to-no impairment of global functioning, it is difficult to assess changes in function in these patients. This can make it difficult to determine if a given treatment's effect is clinically important.

FDA is seeking public comment on the draft guidance for 60 days. Instructions on how to submit comments are included in a related Federal Register notice. In finalizing the guidance document, the agency will consider the information received from the public.

The FDA proposal is part of US Department of Health and Human Services' efforts under the National Plan to Address Alzheimer's Disease, which calls for both the government and the private sector to intensify efforts to treat or prevent Alzheimer's and related dementias and to improve care and services. It responds to recommendations from a May 2012 HHS and National Institutes of Health Alzheimer's research summit to conduct clinical trials in at-risk individuals without symptoms and to develop and validate new measures so that Alzheimer's can be measured at the earliest possible time in the course of the disease.