The behavioural overlap observed between developmental dyslexia and other neurodevelopmental disorders (NDDs) such as ADHD and ASD is an ongoing topic of research. The complexity of these...Show moreThe behavioural overlap observed between developmental dyslexia and other neurodevelopmental disorders (NDDs) such as ADHD and ASD is an ongoing topic of research. The complexity of these conditions, coupled with the overlap in behavioural characteristics, contributes to the challenge of accurately diagnosing dyslexia. Consequently, there is a prevalent tendency for learning disabilities such as dyslexia to be underdiagnosed. This study aims to examine whether there are specific cognitive impairments attributable to dyslexia, that are not observed in NDDs in general. The answer to this question was examined by comparing the cognitive profile of children diagnosed with a NDD and dyslexia to children diagnosed with a NDD but not dyslexia. The WISC-V was administered to 57 children aged between 7 and 16 years. The findings of this study showed no differences in the frequency of a deviant IQ profile between children with a NDD, with or without (suspected) dyslexia. In addition, the results showed no stronger relative weakness on the indexes of working memory, verbal comprehension, and processing speed for children with dyslexia compared to children with a NDD but not dyslexia. To conclude, the current study found no evidence for specific cognitive impairments attributable to dyslexia. Due to the small sample size in this study, further conclusions cannot be drawn from these results. Since the obtained results contradict the results of previous studies, a follow-up study to gain more knowledge about the cognitive profile of dyslexia in co-occurrence with other NDDs is advised.Show less
This study aimed to investigate the relationship of NOTCH3 variant positions, the causal genetic variant of CADASIL, with executive dysfunction measured at baseline as well as two years later at...Show moreThis study aimed to investigate the relationship of NOTCH3 variant positions, the causal genetic variant of CADASIL, with executive dysfunction measured at baseline as well as two years later at follow-up. This was done by comparing NOTCH3 variant positions in groups (risk categories) associated with a high (N = 104) or moderate (N = 76) risk of developing worse disease outcomes. It was expected that the high risk group would perform significantly worse and decline significantly more than the moderate risk group on neuropsychological tests measuring executive functioning. Executive dysfunction was assessed using the following neuropsychological tests: Trail Making Test, Stroop Color and Word Test, WAIS-R Digit Symbol Substitution Test and WAIS-IV Block Design Test. A Linear Mixed Model (Repeated Measurements) analysis was performed to answer the objectives with a total of 180 included participants. There was no significant difference in performance between the risk categories at baseline, nor in the decline in performance over the two-year follow-up span. In an exploratory follow-up analysis, we examined whether decline was present at all, regardless of risk category. This was only the case for one of four neuropsychological tests. In conclusion, future clinical trials are needed to provide better understanding of how NOTCH3 aggregation impacts executive dysfunction and its development thereof within CADASIL. Subsequently, this could allow for more accurate individualised disease progression predictions.Show less
