Neurocognitive variability in high-functioning individuals: implications for the practice of clinical neuropsychology

Knowledge of neurocognitive performance patterns of normal, healthy individuals is necessary, as clinicians may not always take into account normal intra-individual variability, demonstrated here in a sample of 20 healthy individuals with particularly high educational achievement (i.e., holding doctorate degrees). The data indicate that neurocognitive abilities are not equally distributed within a given individual. Some participants in the sample achieved some test scores at the intellectually disabled to borderline range but also some scores in the high average to superior range. The practice of deductive reasoning in clinical neuropsychology may be prone to false positive conclusions about neurocognitive functioning where base rates of neurocognitive impairments are low and pre-existing educational achievements are high.