Are our norms "normal"? A 4-year follow-up study of a biracial sample of rural elders with low education.

Conventional norms that test presumably normal elderly individuals at one point in time may include preclinical cases of dementia and therefore may be less sensitive to the presence of dementia (Sliwinski, Lipton, Buschke, & Stewart, 1996). A sample of presumably normal African American and White rural community older adults (first reported in Marcopulos, McLain, & Giuliano, 1997) were retested after approximately 4 years to develop "robust" norms for the Mini Mental State Examination, Mattis Dementia Rating Scale Fuld Object Memory Evaluation, WAIS-R Vocabulary and Block Design, Wechsler Memory Scale - Revised Logical Memory and Visual Reproduction, Raven's Colored Progressive Matrices, and Clock Drawing Test. Ninety-four out of the original 133 participants were located and agreed to be retested. Twelve of the participants retested at Time 2 showed significant decline on testing relative to their own baseline and were dropped from the recalculated norms. Participants who declined on testing tended to be older, less educated, had lower WAIS-R scores on Vocabulary and Block Design combined, had poorer IADLs and were less socially active. There was no difference in physical health status or level of depression. Recalculated group means showed little change when the participants who declined had been removed, but this left very few participants at the extremes of age (>85 years) and education (<4 years). It appears that the incidence of cognitive decline in this sample is comparable to other community samples of cognitive decline and dementia. Results are discussed in light of the practical difficulties of identifying preclinical dementia for deriving robust norms, implications for the theory of cognitive reserve, risk of cognitive decline in persons with low education and/or low premorbid mental ability and the clinical utility of utilizing education-corrected norms.