The Association Between the Number of Neuropsychological Measures and the Base Rate of Low Scores

Abstract

Obtaining one or more low scores, or scores indicative of impairment, is common in neuropsychological batteries that include several measures even among cognitively normal individuals. However, the expected number of low scores in batteries with differing number of tests is unknown. Using 10 neuropsychological measures from the National Alzheimer’s Coordinating Center database, 1,023 permutations were calculated from a sample of 5,046 cognitively normal individuals. The number of low scores (i.e., z score ≤−1.5) varied for the same number of measures and among different number of measures and did not increase linearly as the number of measures increased. According to the number of low scores shown by fewer than 10% of the sample, cognitive impairment should be suspected for 1 or more, 2 or more, and 3 or more in batteries with up to 2 measures, 3 to 9 measures, and 10 measures, respectively. These results may increase the identification of mild cognitive impairment.

Regression-Based Normative Data for Independent and Cognitively Active Spanish Older Adults: Digit Span, Letters and Numbers, Trail Making Test and Symbol Digit Modalities Test

“…Regarding the results in tests composed of related measures, other studies have shown that for an accurate interpretation of performance in the assessment, it is necessary to consider the correlation among different measures [ 87 , 88 ]. Even though a moderate correlation (r = 0.31–0.6) between Trail A and B has been reported [ 15 ], normative data for the TMT are usually calculated treating both parts as independents.…”

Cognitive Dysfunction, Psychiatric Distress, and Functional Decline After COVID-19

“…Mild/moderate and severe cognitive impairment were defined as performances ≥1.5 and ≥ 2 standard deviations below published age-adjusted normative means for each cognitive test and the global cognitive composite score. Because neurologically healthy individuals may produce one or more low test scores on a cognitive battery, reliance on a single low score may increase the likelihood of false positive findings of impairment( (38) , (39) , (40) ). The likelihood of obtaining one or more low scores increases along with the number of tests in the battery( 39 , 40 ).…”

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

“…Furthermore, it is also important to remember that the base rates of low scores are expected to increase both as the number of tests increases and with a more lenient cut-off (Schretlen et al, 2008 ; Binder et al, 2009 ; Iverson and Brooks, 2011 ). This means that higher rates of false-positive low scores would have been reported in our healthy older people group if we had used a less stringent cut-off value (such as the 16th percentile) or a battery including a higher number of tests for each cognitive domain (Oltra-Cucarella et al, 2019 ). This implies that a higher number of low test-scores should be used as a reliable criterion for identifying (Mistridis et al, 2015 ) or predicting (Bradfield et al, 2020 ) cognitive impairment.…”

“…Many other studies (Palmer et al, 1998 ; Schretlen et al, 2008 ; Brooks et al, 2009a ; Gunner et al, 2012 ; Oltra-Cucarella et al, 2019 ) also highlighted the need to consider base rates of low scores in healthy older individuals (i.e., false positive) in drawing inferences from low-test performances in patients, including those with neurological or psychiatric disorders (Brooks et al, 2009b ; Karr et al, 2017 ). Indeed, the presence of cognitive impairment in patients with LLD may be sometimes due to the development of incipient dementia such Alzheimer's disease (AD) (Rushing et al, 2014 , Ly et al, 2021 ).…”