Trail Making Test, Stroop, and Verbal Fluency: Regression-Based Norms for the Icelandic Population.

OBJECTIVE: The aim of this study was to construct regression-based norms for 3 executive-function tests: the Trail Making Test, Stroop, and Verbal Fluency. METHOD: A sample of 1,034 healthy Icelandic adults (18-64 years) was used to calculate predicted scores for test measures from all 3 tests, controlled for the effects of age, gender, and education, as well as the interaction between these variables. RESULTS: The 3 demographic variables showed significant effects on most test measures and were included in the final equation for estimating predicted scores. An older age and less education predicted worse cognitive performances in most cases, and women tended to outperform men. CONCLUSION: These results highlight the importance of adjusting for age, gender, and educational level when constructing normative data. Controlling for age alone may be insufficient or misleading in clinical-practice settings. A simple, user-friendly program for predicting executive-function test scores is provided.

Cognitive Measures and Performance on the Antisaccade Eye Movement Task.

The antisaccade (AS) task is considered a prominent measure of inhibitory control, but it is still unclear which cognitive processes are used for successful performance of the task. Previous results have provided evidence for the involvement of several processes, including working memory (WM), inhibition and attention. Thus, the aim of this study was to explore, using a range of neuropsychological tests, which cognitive factors predict individual differences in AS performance. To do so, 143 healthy participants underwent a battery including tests measuring inhibition, working memory, cognitive flexibility, sustained attention, IQ and fluency. Hierarchical stepwise regression analyses were conducted to assess the association with AS performance. Performance on the Trail-Making-Test, version B (TMT-B), a test measuring flexibility, divided attention and WM, was found to significantly predict AS latency. Rapid Visual Information Processing (RVIP), used to assess sustained attention and WM, significantly predicted AS error rate. Other cognitive measures, however, did not significantly predict AS performance. Bayesian Model Averaging supported these conclusions and showed that non-significant predictors are unlikely to be associated with AS outcomes. Several explanations are provided for the associations of TMT-B and RVIP with AS performance; as the tests measure a range of different cognitive processes, interpretation of these results remains less clear. For a better understanding of the cognitive mechanisms underlying AS performance, future research should make use of a wider range of attention and WM tests.

15q11.2 CNV affects cognitive, structural and functional correlates of dyslexia and dyscalculia.

Several copy number variants have been associated with neuropsychiatric disorders and these variants have been shown to also influence cognitive abilities in carriers unaffected by psychiatric disorders. Previously, we associated the 15q11.2(BP1-BP2) deletion with specific learning disabilities and a larger corpus callosum. Here we investigate, in a much larger sample, the effect of the 15q11.2(BP1-BP2) deletion on cognitive, structural and functional correlates of dyslexia and dyscalculia. We report that the deletion confers greatest risk of the combined phenotype of dyslexia and dyscalculia. We also show that the deletion associates with a smaller left fusiform gyrus. Moreover, tailored functional magnetic resonance imaging experiments using phonological lexical decision and multiplication verification tasks demonstrate altered activation in the left fusiform and the left angular gyri in carriers. Thus, by using convergent evidence from neuropsychological testing, and structural and functional neuroimaging, we show that the 15q11.2(BP1-BP2) deletion affects cognitive, structural and functional correlates of both dyslexia and dyscalculia.