Cognitive difficulties are argued to be common in patients with Noonan syndrome spectrum disorders (NSSDs), but findings are based on studies in which patients with variants in PTPN11 (prevalence ~50%) were overrepresented. The current study, using a structured clinical approach, describes the cognitive phenotype and psychopathology of 100 patients (aged 6 to 61 years) with nine different gene variants in the Ras/MAPK pathway underlying NSSDs (PTPN11n = 61, PTPN11 Noonan syndrome with multiple lentigines n = 3, SOS1n = 14, KRASn = 7, LZTR1n = 5, RAF1n = 4, SHOC2n = 2, CBLn = 2, SOS2n = 2). After weighted assessment and bootstrapping of the results of individual neuropsychological assessments and measures of psychopathology, cognitive performances in most variant groups were within the ranges of expectation. IQs were significantly lower in patients with variants in PTPN11, KRAS, RAF1, and SHOC2, but no specific cognitive impairments were found. The performances of younger participants (<16 years of age) did not differ from those of adults. Alexithymia and internalizing problems were more frequent in patients with variants in PTPN11 and SOS1, while PTPN11 patients also showed higher levels of externalizing problems. These results stress the need to take intelligence into account when interpreting lower cognitive performances in individual neuropsychological assessments, which is crucial for an adequate understanding and guidance of patients with NSSDs.

Noonan syndrome (NS) is a genetic disorder characterised by short stature, facial dysmorphia, congenital heart defects and mildly lowered intellectual abilities. Research has mainly focused on genetic and somatic aspects, while intellectual and cognitive functioning has been documented scarcely. Also, to date studies have been primarily performed in children. This is the first study in which functioning within the major cognitive domains is systematically evaluated in a group of adults with NS and compared with a control group. Extensive neuropsychological assessment, including the domains intelligence, speed of information processing, memory (working memory, immediate recall and delayed recall), executive function and visuoconstruction, was performed in a sample of 42 patients with NS and 42 healthy controls, matched on age, sex and education level. In addition, subjective cognitive complaints were assessed with self-report questionnaires. On the domain speed of information processing patients performed worse than controls (P < 0.05). Furthermore, except for slightly better results on delayed recall in the patients with NS (P < 0.05), none of the other cognitive domains showed between-group differences. On the questionnaires, patients reported substantially more complaints about their own cognitive abilities than controls (P < 0.05). A lowered speed of information processing and relatively intact functioning in other cognitive domains characterises the cognitive profile of adult patients, in contrast to previous findings in children with NS, who seem to have more generalised cognitive deficits.

Purpose: Noonan syndrome (NS) is a genetic disorder that is associated with social cognitive problems. While treatment aimed at the improvement of social cognition is available for other neuropsychiatric disorders, no such interventions yet exist for NS patients. In this study, the development of the first social cognitive training for NS patients is described and its applicability and feasibility evaluated. Methods: Eleven adult patients with NS participated in this controlled proof-of-principle study. Six patients were included in the treatment group and five in the control group. Neuropsychological testing was performed in both groups at baseline and posttreatment. Social cognition was a primary outcome measure and nonsocial cognition and psychopathology secondary outcome measures. Differences between pre- and posttest were investigated with Wilcoxon signed-rank tests, and a process evaluation was performed to aid interpretation of the results. Results: Both groups were comparable with regard to age, estimated intelligence, and baseline performance. Although no significant differences were found between pre- and posttest scores on primary and secondary outcome measures in either group, a medium–large effect size was found on emotion recognition in the treatment group. Also, the process evaluation demonstrated the feasibility of the training. Conclusion: This first social cognitive training for adult patients with NS has proven to be feasible for this population and showed some encouraging results regarding emotion recognition, although the training protocol could be optimized. Further investigation is required using a randomized controlled design in a larger sample, in order to substantiate the overall effectiveness of the training.

The current study aims to examine executive and social functioning in children and adolescents with Noonan syndromes, which contributes to the understanding of the cognitive and behavioral profile of this population and possible treatment options. A total of 26 children and adolescents with Noonan syndromes (including Noonan syndrome, Noonan syndrome with multiple lentigines, and Noonan-like syndrome with loose anagen hair; mean age = 11.92 years, SD = 2.64) and 25 typically developing children and adolescents (mean age = 10.32 years, SD = 2.75) participated in this study. Cognitive and behavioral measures of executive and social functioning of children and adolescents in these groups were compared using multivariate analyses of variance. Moreover, the relationship between executive and social functioning was examined. Results showed significant group differences on working memory and attention, with controls outperforming children and adolescents with Noonan syndromes, even when controlling for crystallized intelligence. At a behavioral level, children and adolescents with Noonan syndromes experienced more executive function problems and more characteristics of attention-deficit/hyperactivity disorder and autism spectrum disorders in daily life than controls, even when controlling for crystallized intelligence. Positive relationships were found between behavioral measures of executive functions and characteristics of autism spectrum disorders. Difficulties in working memory and attention seem to be key cognitive features in children and adolescents with Noonan syndromes. These difficulties occur alongside parental reports of executive function problems, characteristics of attention-deficit/hyperactivity disorder, and autism spectrum disorders.