Lack of Practice Effects on Neuropsychological Tests as Early Cognitive Markers of Alzheimer Disease?

Abstract

Reliable assessment of change from previous cognitive functioning is a prerequisite for determining the possible presence of neurodegenerative diseases such as Alzheimer's disease (AD). We investigated whether standardized change scores on the German version of the Consortium to Establish a Registry for Alzheimer's Disease-Neuropsychological Assessment Battery (CERAD-NAB) could be used for early diagnosis of AD and whether change scores on the CERAD-NAB are superior in this respect to scores recorded on 1 occasion only. Three hundred seventy-four normal control subjects were assessed twice. Data from 95 patients with mostly mild probable AD were collected at their first entry to a memory clinic and an average of 1.1 +/- 0.24 years later. It is concluded that repeated testing with the CERAD-NAB does not generally add to improved diagnostic accuracy for mild and very mild AD and cannot, therefore, be recommended as a routine clinical procedure.

Early detection of Alzheimer’s disease with a total score of the German CERAD

“…Thus, the relatively high CCRs between 84.2% and 87.9% most likely underestimate the potential of these scores to correctly classify individuals on the basis of their change in cognitive performance over time and thus also the constructed combination scores. Similar to our global scores, Zehnder et al ( 2007 ) reported that individual CERAD-NAB subtest baseline and change scores both showed excellent diagnostic discriminability for NC and AD in groups who had the same test-retest intervals as the present study. Moreover, 78% of AD patients with follow-up testing had received acetylcholine-esterase inhibitor treatment between baseline and follow-up, which may also have weakened differences between the CERAD total scores of NC and AD participants.…”

“…ch ; Aebi, 2002 ;Thalmann et al, 2000 ). The CERAD has also proven sensitive to cognitive impairments occurring in the early stages of dementia and to cognitive changes over long time spans (Fillenbaum, Unverzagt, Ganguli, Welsh-Bohmer, & Heyman, 2002 ;Morris et al, 1989Morris et al, , 1993Welsh, Butters, Hughes, Mohs, & Heyman, 1991, 1992Zehnder, Bläsi, Berres, Spiegel, & Monsch, 2007 ). Chandler et al ( 2005 ) recently developed a total score for the American version of the CERAD-NAB.…”

Evaluation of a Summary Score of Cognitive Performance for Use in Trials in Perioperative and Critical Care

“…It has established itself as the standard in the evaluation of dementia syndromes in memory clinics, at least throughout German-speaking Europe. The CERAD-NAB assesses a wide variety of cognitive functions, is easy to administer after appropriate training (also by non-psychologists), is standardized, and there are normative values for normal controls from the CERAD registry [6,8,19] and from several observational and longitudinal studies [20,21,22], and from 1,100 elderly Swiss individuals allowing calculation of demographically adjusted (age, gender, and education) standard scores [17,23]. Apart from English and German, the CERAD-NAB has been translated into several languages and validated in different cultures [24,25,26,27,28,29,30,31,32].…”

“…Practice effects with repeated administration of neuropsychological tests have been reported for a variety of tests and after various time intervals in adults and children, as well as in brain-injured patients [23,36,37]. Practice effects may be due to increased familiarity with test-taking procedures, test-taking strategies, fewer feelings of fear or nervousness, a reduced sense of novelty at the time of retest, so-called test sophistication [38], and remembering specific test items.…”

“…With the German version of the CERAD-NAB, healthy volunteers showed statistically significant practice effects in verbal learning (word list) and visual memory – constructional praxis (savings) – after 2.4 ± 0.28 years, whereas there were no practice effects found in semantic fluency, Boston Naming Test, and constructional praxis (delayed recall of figures) [23]. As it is unlikely that specific test items were memorized for more than 2 years, the authors suppose that the observed improvement was due to test sophistication [38].…”