SOURCE: Xtalks

Xtalks Webinars

July 05, 2016 07:00 ET

The Preclinical Alzheimer Cognitive Composite (PACC): From Theory to Practical Application in Global Clinical Trials, New Webinar Hosted by Xtalks

TORONTO, ON--(Marketwired - July 05, 2016) - During a live session on July 20, 2016, Paul Maruff, Chief Science Officer and Edward Bartolic, Senior Science Director, both from Cogstate, will discuss PACC component tests -- how they were selected, paradigms measured, and applications of the composite as a primary endpoint in clinical trials. Additionally, the presenters will outline the challenges to implementation and possible solutions including: translating and culturally adapting the tests for global deployment, training raters for reliable and accurate administration and monitoring data quality during studies. An outline of possible alternative component measures and the potential pros and cons will also be included.

Drug development strategies for early Alzheimer's disease (AD) require clinical endpoints that are sensitive to the subtlest cognitive changes that may be occurring at even preclinical stages. Commonly used measures of cognition in clinical trials of treatments for Alzheimer's disease, such as the Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog) and the Clinical Dementia Rating (CDR), have inadequate measurement properties (e.g., ceiling effects, practice effects, restricted range, and/or skewed distributions), which render them insensitive to subtle change.

The most common approach to defining novel endpoints has been to assemble composite measures by combining tests, or specific items of tests, which assess domains of cognitive function that have historically been shown to be most sensitive to change in studies of early clinical populations (i.e., mild cognitive impairment or prodromal AD) or in observational studies of preclinical, "at-risk" samples.

One such composite measure, the Alzheimer's Disease Cooperative Study-Preclinical Alzheimer Cognitive Composite (ADCS-PACC), was based on retrospective analyses of datasets from 3 longitudinal, observational studies of cognitively normal elderly individuals. These studies were the Australian Imaging, Biomarkers, and Lifestyle (AIBL) Flagship Study of Aging, the Alzheimer's Disease Neuroimaging Study (ADNI), and the ADCS Prevention Instrument (ADCS-PI) study. Those members of the study samples with risk factors for Alzheimer's disease, such as positive brain amyloid (AIBL, ADNI) or ApoE4 allele (ADCS-PI), showed the greatest decline relative to members without risk factors on measures of episodic memory (delayed word recall and delayed story recall), executive functioning, and orientation. Although the specific tests were not completely aligned across the three studies, the following tests and outcome scores were proposed as the PACC:

  • Free and Cued Selective Reminding Test (FCSRT) -- Total Free and Cued Recall Score
  • Logical Memory from the Wechsler Memory Scale -- Delayed Recall Score (from a single story)
  • Digit Symbol-Coding from the Wechsler Intelligence Scale -- Number of Correct Symbols
  • Mini-Mental Status Examination (MMSE) -- Total MMSE score

The ADCS-PACC is currently being prospectively validated in a number of ongoing studies, including the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study.

To learn more about this complimentary event, visit: The Preclinical Alzheimer Cognitive Composite (PACC): From Theory to Practical Application in Global Clinical Trials

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