Effective Normative Samples For the Detection Of Cognitive Impairment in Older Adults

Abstract

The inclusion of individuals with incipient dementia in normative data contaminates the distinction between normal and pathological aging. Conventional and Robust (excluding persons with incipient dementia) norms were created using data from the Canadian Study of Health and Aging (CSHA). Robust norms were not significantly better at distinguishing between normal and pathological aging. Norms reflecting the relationship between age and the prevalence of dementia revealed a probability of dementia of less than 35%. The results of the norming procedure serve to illustrate the validity of our current measures and methods for identifying cognitive impairment. CSHA Conventional norms are adequate for the identification of cognitive impairment.

Keywords:

• Aged
• Cognitive impairment
• Comparative norms
• Conventional norms
• Diagnostic norms
• Older adults
• Robust norms

ACKNOWLEDGMENTS

L. J. Ritchie was aided in the manuscript preparation by a doctoral award from the Alzheimer Society of Canada Research Program. A research personnel award from the Canadian Institutes of Health Research, Institute of Aging provided support for the third author in the preparation of this manuscript.

Phases 1 and 2 of the Canadian Study of Health and Aging core study were funded by the Seniors' Independence Research Program, through Health Canada's National Health Research and Development Program (NHRDP project #6606-3954-MC(S)); supplementary funding for analysis of the caregiver component was provided by the Medical Research Council. Additional funding was provided by Pfizer Canada Incorporated, through the Medical Research Council/Pharmaceutical Manufacturers Association of Canada Health Activity Program, NHRDP (project #6603-1417-302(R)), by Bayer Incorporated, and by the British Columbia Health Research Foundation (projects #38 (93-2) and #34 (96-1)). Core funding for Phase 3 was obtained from the Canadian Institutes for Health Research (CIHR grant # MOP-42530); supplementary funding for the caregiver component was obtained from CIHR grant #MOP-43945. Additional funding was provided by Merck-Frosst and by Janssen-Ortho Inc. The study was coordinated through the University of Ottawa and Health Canada.

Notes

CSHA: Canadian Study of Health and Aging.

*Overestimated the variance compared to Robust1 Norms.

^#Overestimated the variance compared to Robust2 Norms.

FR 1 = Free Recall Trial 1; RAVLT = Rey Auditory Verbal Learning Test; BVRT = Benton Visual Retention Test Revised; WAIS-R = Wechsler Adult Intelligence Scale Revised.