Mayo normative studies: regression-based normative data for ages 30-91 years with a focus on the Boston Naming Test, Trail Making Test and Category Fluency

Abstract

Objective: Normative neuropsychological data are essential for interpretation of test performance in the context of demographic factors. The Mayo Normative Studies (MNS) aim to provide updated normative data for neuropsychological measures administered in the Mayo Clinic Study of Aging (MCSA), a population-based study of aging that randomly samples residents of Olmsted County, Minnesota, from age- and sex-stratified groups. We examined demographic effects on neuropsychological measures and validated the regression-based norms in comparison to existing normative data developed in a similar sample.

Method: The MNS includes cognitively unimpaired adults ≥30 years of age (n = 4,428) participating in the MCSA. Multivariable linear regressions were used to determine demographic effects on test performance. Regression-based normative formulas were developed by first converting raw scores to normalized scaled scores and then regressing on age, age², sex, and education. Total and sex-stratified base rates of low scores (T < 40) were examined in an older adult validation sample and compared with Mayo's Older Americans Normative Studies (MOANS) norms.

Results: Independent linear regressions revealed variable patterns of linear and/or quadratic effects of age (r² = 6-27% variance explained), sex (0-13%), and education (2-10%) across measures. MNS norms improved base rates of low performance in the older adult validation sample overall and in sex-specific patterns relative to MOANS.

Conclusions: Our results demonstrate the need for updated norms that consider complex demographic associations on test performance and that specifically exclude participants with mild cognitive impairment from the normative sample.

Keywords: Cognitive aging; animal fluency; base rates; executive function; mild cognitive impairment; neuropsychological tests; neuropsychology; psychometrics.

Figure 1.

Predicted scores from models show the effect of age, age squared, sex (women, solid lines; men, dashed lines), and years of education (blue, 20 years; green, 16 years; orange, 12 years; red, 8 years) on each category fluency trial (top row) and for Boston Naming Test, Trails A seconds reversed and Trails B seconds reversed (bottom row). Figure used with permission of Mayo Foundation for Medical Education and Research, all rights reserved.

Figure 2.

Observed proportions of the validation sample (N=261) showing low test performance (SS < 7 for age-corrected MOANS; SS < 7 for age and education-corrected MOANS; T < 40 for age, sex and education-corrected MNS) with 95% Confidence Intervals (CIs). CIs that do not contain the 14.7% expected base rate value (vertical dashed line) are significantly different than expected. Note. Adj = adjusted. BNT = Boston Naming Test. MNS = Mayo Normative Studies. MOANS = Mayo’s Older Americans Normative Studies. TMTA = Trail Making Test Part A. TMTB = Trail Making Test Part B. When both age-adjusted and age and education-adjusted MOANS norms are available, both are provided above. Logical Memory and Visual Reproduction MOANS are only adjusted for age (Ivnik et al., 1992a). Fully-adjusted MNS adjusts for age, age squared, sex and education. Numeric values corresponding to this figure are available in Supplemental Table 4. Figure used with permission of Mayo Foundation for Medical Education and Research, all rights reserved.

Figure 3.

Observed proportions of the validation sample by sex (n=130 females; n=131 males) showing low test performance (SS < 7 for age-corrected MOANS; T < 40 for age, sex and education-corrected MNS) with 95% Confidence Intervals (CIs). CIs that do not contain the 14.7% expected base rate value (vertical dashed line) are significantly different than expected. Note. Adj = adjusted. BNT = Boston Naming Test. MNS = Mayo Normative Studies. MOANS = Mayo’s Older Americans Normative Studies. TMTA = Trail Making Test Part A. TMTB = Trail Making Test Part B. Fully-adjusted MNS adjusts for age, age squared, sex and education. Only age-adjusted MOANS norms are presented in this figure for simplicity, but age and education-adjusted MOANS norms are available in Supplemental Table 4 for measures where those are available. Figure used with permission of Mayo Foundation for Medical Education and Research, all rights reserved.