Effects of patient age on neuropsychological test interpretation.

Abstract

Normative test data for a 38-year-old and for a 74-year-old were obtained for the Halstead-Reitan Neuropsychological Battery, the Wechsler Adult Intelligence Scale-Revised, and the Wechsler Memory Scale. These test protocols were presented for blind interpretation to a random sample of psychologists specializing in neuropsychology. Test results for the "average" elderly person were interpreted as normal less frequently (42%) than results for the "average" younger adult (93%). The elderly person's test results also received higher impairment ratings and were frequently interpreted as reflecting dementia (23%). Subject's level of confidence with decisions made did not have an impact on accuracy rates. In addition, personal, training, and professional variables were not significantly related to judgment accuracy. The results suggest a tendency for misinterpretation of normal elderly persons' test performance.Neuropsychological assessment is commonly used to differentiate the effects of normal aging from those of cerebral pathology. This objective is ideally accomplished by comparing an elderly patient's test results with norms developed from the data from both normal and pathologically impaired elderly subjects. A difficulty that can arise in evaluating the elderly, however, is that test results of an older person may be compared with norms obtained from a sample of younger adults (Albert, 1981;Heaton, Grant, & Matthews, 1991). The use of such norms can result in incorrect interpretations of test findings and lead to inappropriate recommendations for an elderly patient. For example, several studies have shown that a large percentage of normal elderly subjects are misclassified as brain damaged when standard adult norms are used (

Confidence in psychodiagnosis: what makes us so sure?

“…Research has demonstrated that individuals working under conditions of uncertainty tend to overestimate the probability that their judgments are correct, and it appears that mental health professionals are as susceptible to overconfidence as non-professionals (Faust, Hart, Guilmette, & Arkes, 1988;Nadler, Mittenburg, DePiano, & Schneider, 1994;Rabinowitz & Garelik-Wyler, 1999). However, we know little about the sources of this overconfidence.…”

Observations on the validity of neuropsychological and personality assessment testing

“…Deception was practised: although the neuropsychologists were told that the results were obtained for a 38-year-old client and a 74-year-old client, they were actually given average scores for relatively normal 38-year-old and 74-year-old individuals residing in the community (these values were based on normative data). With regard to results, in the study by Nadler et al (1994), diagnoses of dementia were never made for the 38-year-old client, but 23% of the neuropsychologists made this diagnosis for the 74-year-old client. This result is remarkable because the client was described using the test results for 74-year-old individuals in the community with no known neurological disorder.…”

“…Evidence for age bias has been mixed (Garb & Boyle, in press;Nadler, Mittenberg, DePiano, & Schneider, 1994). In both studies, neuropsychologists made diagnoses for a 38-year-old client and a 74-year-old client.…”

Vocabulary Knowledge is Not a Predictor of General Cognitive Functioning in Elderly People with Very Low Educational Attainment

“…Specifically, the performance on neuropsychological assessment in normal elderly people with very low educational attainment is significantly lower with greater variability than those with more educational attainment 23. This puts elderly people with low education at higher risk for misdiagnosis with pathological aging in the clinical setting, including mild cognitive impairment 456. Estimating premorbid cognitive functioning with an appropriate measure is crucial for accurate diagnosis and thereby, would contribute to effective prevention and treatment of neurocognitive disorders in these individuals.…”