Healthy children get low scores too: prevalence of low scores on the NEPSY-II in preschoolers, children, and adolescents.

Knowing the prevalence of low test scores in healthy people is valuable for clinical interpretation of neuropsychological performance because it reduces the likelihood of over-diagnosing cognitive deficits. Base-rate information on adult batteries has flourished recently but is relatively unknown for pediatric tests. The purpose of this paper is to present the base rates of low scores for a pediatric neuropsychological battery, the NEPSY-II. Participants included 1,200 healthy preschoolers, children, and adolescents between 3 and 16 years of age from the NEPSY-II standardization sample. Measures included subtests from the attention and executive functioning, language, learning and memory, and visuospatial processing domains, organized to yield a 1- and 2-hr battery with optimal reliability. Analyses were conducted for three age groups (3-4, 5-6, and 7-16 years) and stratified by the level of parental education (<or=11, 12, 13-15, and 16+ years). In 3-4-year-olds, it was uncommon to have three or more scores <or=10th percentile. For 5-6-year-olds, having three or more low scores on the 1- or 2-hr battery was uncommon. In 7-16-year-olds, it was uncommon to have four or more low scores on a 1-hr battery and uncommon to have five or more low scores on a 2-hr battery. With all age groups, the prevalence of low scores decreased substantially with higher levels of parental education. Consistent with the literature on base rates of low scores in adult batteries, having some low scores is common in healthy children. Look-up tables are provided to help in the clinical interpretation of low scores with preschoolers, children, and adolescents.