BASE RATES OF IMPAIRED NEUROPSYCHOLOGICAL TEST-PERFORMANCE AMONG HEALTHY OLDER ADULTS

Base rates deficient neuropsychological test performance were evaluate d among 132 neurologically healthy older normal adults rising a variet y of measures commonly employed in the ''flexible battery'' approach t o neuropsychological assessment. Subjects were divided into three age groups (50 to 59, 60 to 69, and 70 to 79 years). Despite the healthy s tatus of our sample, most rests yielded at least some proportion of su bjects earning scores iii the borderline and impaired ranges (1.3 and 2.0 standard deviations below the age-group mean, respectively). Acros s the battery of measures, 73% of subjects earned a borderline score o n at least one measure, and 20% of subjects earned at least two scores in the impaired range on separate tests. The proportion of subjects c onsistently earning borderline or impaired scores across multiple meas ures within specific cognitive domains was generally lower. Results il lustrate the problems in interpreting isolated low scores, and the nee d to consider false-positive base rates in drawing inferences om poor rest performance. (C) 1998 National Academy of Neuropsychology. Publis hed by Elsevier Science Ltd.