Prediction of memory and language performance in normal elderly Canadians : implications for the assessment of premorbid cognition in early Alzheimer's disease




Carswell, Lisa Marie

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The present study examined the concurrent validity of several proposed measures of premorbid IQ, present ability measures, and demographic variables at predicting intellectual, verbal memory, and language performance in a sample of 98 normal elderly Canadians (mean age = 71.9 years). Predictive regression equations were developed to estimate performance on criterion measures in each cognitive domain including general intellectual ability (i.e. Wechsler Adult Intelligence Scale-Revised Verbal IQ: WAIS-R VIQ), verbal memory (i.e. California Verbal Learning Test long delayed free recall: CVLTLDFR), and language domains (i.e. Boston Naming Test: BNT). These new regression equations utilized a combination of measures of premorbid VIQ and present ability measures to account for 63%, 32% and 54% of the variance in WAIS-R VIQ, CVLTLDFR, and BNT performance, respectively. The utility of these new equations for detecting impaired performance and cognitive decline in clinical samples was evaluated by calculation of sensitivity scores for each equation based on the method proposed by Graves, Carswell & Snow (in press). The results indicated that performance would have to decline by approximately 15 points for WAIS-R VIQ, 6 points for CVLTLDFR, and 6 points for BNT scores, to be reliably detected 80% of the time. The implications of the sensitivity of each of these equations was discussed with regard to the clinical application of these equations for predicting premorbid cognition in early Alzheimer's disease. The current study was also the first study to develop predictive regression equations utilizing measures of premorbid VIQ and present ability measures to estimate verbal memory and language performance in a healthy elderly sample.



Older people, Alzheimer's disease, Memory in old age, Cognition in old age