The second, a six-stage numerical clinical staging scheme, will apply only to those who are amyloid-positive and on the Alzheimer’s continuum. Stages run from 1 (unimpaired) to 6 (severe dementia). The numeric staging does not concentrate solely on cognition but also takes into account neurobehavioral and functional symptoms. It includes a transitional stage during which measures may be within population norms but have declined relative to the individual’s past performance.
The numeric staging scheme is intended to mesh with FDA guidance for clinical trials outcomes, the committee noted.
“A useful application envisioned for this numeric cognitive staging scheme is interventional trials. Indeed, the NIA-AA numeric staging scheme is intentionally very similar to the categorical system for staging AD outlined in recentfor industry pertaining to developing drugs for treatment of early AD … it was our belief that harmonizing this aspect of the framework with FDA guidance would enhance cross fertilization between observational and interventional studies, which in turn would facilitate conduct of interventional clinical trials early in the disease process.”
The entire system yields a shorthand biomarker profile entirely unique to each subject. For example an A+T-(N)+ MCI profile suggests that both Alzheimer’s and non-Alzheimer’s pathologic change may be contributing to the cognitive impairment. A cognitive staging number could also be added.