The RAPID Neuropsychological Test Battery for Subjects Aged 50-89: From Norms to Cognitive Profile.

BACKGROUND/AIMS: It is well established that healthy adults obtain low performances when simultaneously interpreting the results of multiple tests. The aim of this study was to estimate the proportion of French-speaking healthy older adults with low scores for the RAPID (Réseau d'Aide au diagnostic et à la PrIse en charge des Détériorations cognitives et de maladies neurologiques chroniques en Franche-Comté et au niveau national) battery test and consider different combinations of test scores within a specific domain and across different domains. METHODS: The prevalence of low scores (i.e., ≤5th percentile) on the 14 RAPID primary measures was calculated from the RAPID normative sample (n = 476), based on 4 ages (50-89 years) and 3 levels of education. RESULTS: A high percentage (40.1%) of the normative sample obtained at least one or more low scores (i.e., false positives). In contrast, the risk of having low scores was much less important (<2%) when considering the combinations of 2 test-scores. CONCLUSION: Low scores are very common in healthy older subjects and are thus not necessarily pathological or indicative of truly impaired functioning. The information derived from a cognitive profile may provide a greater clinical relevance in an individual, since very few of the healthy older adults obtained low scores on combinations of 2 test-scores.

Cognitive Impairment in Late-Life Depression: A Comparative Study of Healthy Older People, Late-Life Depression, and Mild Alzheimer's Disease Using Multivariate Base Rates of Low Scores.

Late-Life Depression (LLD) is often associated with cognitive impairment. However, distinction between cognitive impairment due to LLD and those due to normal aging or mild Alzheimer's Disease (AD) remain difficult. The aim of this study was to present and compare the multivariate base rates of low scores in LLD, mild AD, and healthy control groups on a battery of neuropsychological tests. Participants (ages 60-89) were 352 older healthy adults, 390 patients with LLD, and 234 patients with mild AD (i.e., MMSE ≥ 20). Multivariate base rates of low scores (i.e., ≤ 5th percentile) were calculated for each participant group within different cognitive domains (verbal episodic memory, executive skills, mental processing speed, constructional praxis, and language/semantic memory). Obtaining at least one low score was relatively common in healthy older people controls (from 9.4 to 17.6%), and may thus result in a large number of false positives. By contrast, having at least two low scores was unusual (from 0.3 to 4.6%) and seems to be a more reliable criterion for identifying cognitive impairment in LLD. Having at least three low memory scores was poorly associated with LLD (5.9%) compared to mild AD (76.1%) and may provide a useful way to differentiate between these two conditions [ χ ( 1 ) 2 = 329.8, p < 0.001; Odds Ratio = 50.7, 95% CI = 38.2-77.5]. The multivariate base rate information about low scores in healthy older people and mild AD may help clinicians to identify cognitive impairments in LLD patients, improve the clinical decision-making, and target those who require regular cognitive and clinical follow-up.

Spectrum Effect and Spectrum Bias in the Screening Test Performance for Amnestic Mild Cognitive Impairment: What are the Clinical Implications?

BACKGROUND: A single cutoff is widely used to screen amnestic mild cognitive impairment (aMCI). However, results of screening test performance are never adjusted for spectrum effect and spectrum bias. OBJECTIVES: To assess the potential impact of spectrum effect and spectrum bias on screening test performance and clinical decision. METHODS: The ability of the combination of Memory Impairment Screen (MIS), the Isaacs Set Test (IST), and the Mini-Mental State Examination (MMSE) to distinguish aMCI (n = 3,330) from patients with subjective cognitive complaints (SCC) (n = 1,522) was investigated across a wide range of age and educational backgrounds. The spectrum effect was defined as the variation of the sensitivity and/or the specificity across different subgroups. A spectrum bias was highlighted if the likelihood ratio (LR) observed in a subgroup of subjects statistically differed from the LR observed in the overall sample. RESULTS: For the MIS-IST pairing, the overall sensitivity and specificity were equal to 72.5% and 75.2% , the positive LR (LR+) and the negative LR (LR-) were equal to 2.91 and 0.37, respectively. Across the different age-education subgroups, the sensitivities ranged from 43.7% to 92.5% and specificities from 39.3% to 95.2%. LR+ and LR- ranged from 1.51 to 9.10 and 0.13 to 0.59, respectively. A statistically significant spectrum bias was found in some subgroups and may result in differences between the post-test probabilities. Similar results were also found for the MMSE. CONCLUSION: These findings could potentially affect the clinician's decision with a possible greater impact in elderly patients with a lower educational level.