The Role of Executive Function in Independent Living Skills in Female Adolescents and Young Adults With Fragile X Syndrome

Immersive virtual reality is more effective than non-immersive devices for developing real-world skills in people with intellectual disability

BACKGROUND

People with intellectual disability (ID) demonstrate persistent challenges around developing life skills. Immersive virtual reality (IVR) is gaining interest as a tool for training life skills as it enables individuals to engage in hands-on learning in a safe, controlled and repeatable environment. However, there are concerns about the potential drawbacks of IVR, such as cybersickness and practical challenges with using the equipment, which may hinder its widespread adoption in educational settings. The current study aimed to compare the effectiveness of training in IVR and a non-immersive virtual environment for improving real-world skills in people with ID.

METHODS

In the present study, 36 adults (16 female, 20 male) with ID were recruited from a disability organisation. Participants completed a real-world assessment of waste management skills before and after training in either the IVR or non-immersive group.

RESULTS

Consistent with our hypotheses, the IVR group scored significantly higher in the real-world assessment after virtual training (d = 1), and at the 1-week follow-up (d = 1.12), compared with the non-immersive group. Further analyses showed that the IVR group, but not the non-immersive group, significantly improved performance in the real-world assessment across timepoints.

CONCLUSIONS

The findings indicate that IVR was more effective for improving and retaining real-world waste management skills. This study supports IVR as a viable tool for professionals and caregivers to develop skills for independent living among people with ID.

The latent structure of the Delis-Kaplan system for autism

A core feature of autism is deficits in executive functioning (EF), including difficulty with planning, cognitive flexibility, and working memory. Despite a growing need for evidence-based assessments of EF for autism populations, statistical models of many commonly used measures of EF, including the Delis-Kaplan Executive Function System (D-KEFS), have not been investigated for a sample of autistic participants. The purpose of this study was to address a gap in the literature regarding the latent structure of the D-KEFS in a sample of autistic individuals. The D-KEFS is one of the most widely used clinical assessments of executive function, but its factor structure has not been examined in a sample of autistic participants. Reliability analyses were performed for sample subgroups based on participants' clinical and demographic characteristics, including IQ, autism severity, age, and race/ethnicity. Verbal Fluency (VF) was found to consistently decrease or not affect the overall reliability score. Additionally, one- and two-factor structure models were tested for the D-KEFS with a sample of autistic participants. The one-factor model was not found to be a good fit for the data. However, the two-factor model, with Cognitive Flexibility and Abstraction latent factors, was found to fit the data relatively well. This two-factor model was reexamined excluding the VF observed variable, resulting in a better overall model fit. Communication deficits are a common feature of autism, which explains why the VF task, that requires participants to produce novel words, may not be an adequate measure of executive function for autism populations.

Research Gaps in Fragile X Syndrome: An Updated Literature Review to Inform Clinical and Public Health Practice

OBJECTIVE

The phenotypic impact of fragile X syndrome (FXS) has been well-documented since the discovery of the fragile X messenger ribonucleoprotein 1 gene 30 years ago. However, gaps remain in clinical and public health research. The purpose of this literature review was to determine the extent to which these gaps have been addressed and identify targeted areas of future research.

METHODS

We conducted an electronic search of several scientific databases using a variety of key words. The search focused on 5 areas identified as research gaps by an earlier review: (1) diagnosis, (2) phenotypic presentation, (3) familial impact, (4) interventions and treatments, and (5) life span perspectives. Inclusion criteria included publication between 2014 and 2020, focus on human subjects, and publication in English. A total of 480 articles were identified, 365 were reviewed, and 112 are summarized in this review.

RESULTS

Results are organized into the following categories: (1) FXS phenotype and subtypes (FXS subtypes, medical profile, cognitive/developmental profile, social and behavioral profile); (2) needs of adults; (3) public health needs (clinical diagnosis and newborn screening, health care needs, and access); (4) treatment (treatment priorities, pharmacological treatments, and behavioral and educational interventions); and (5) families (economic burden and mother-child relationship).

CONCLUSION

Despite the progress in many areas of FXS research, work remains to address gaps in clinical and public health knowledge. We pose 3 main areas of focused research, including early detection and diagnosis, determinants of health, and development and implementation of targeted interventions.

Altered frontal connectivity as a mechanism for executive function deficits in fragile X syndrome

BACKGROUND

Fragile X syndrome (FXS) is the leading inherited monogenic cause of intellectual disability and autism spectrum disorder. Executive function (EF), necessary for adaptive goal-oriented behavior and dependent on frontal lobe function, is impaired in individuals with FXS. Yet, little is known how alterations in frontal lobe neural activity is related to EF deficits in FXS.

METHODS

Sixty-one participants with FXS (54% males) and 71 age- and sex-matched typically-developing controls (TDC; 58% males) completed a five-minute resting state electroencephalography (EEG) protocol and a computerized battery of tests of EF, the Test of Attentional Performance for Children (KiTAP). Following source localization (minimum-norm estimate), we computed debiased weighted phase lag index (dWPLI), a phase connectivity value, for pairings between 18 nodes in frontal regions for gamma (30-55 Hz) and alpha (10.5-12.5 Hz) bands. Linear models were generated with fixed factors of group, sex, frequency, and connection. Relationships between frontal connectivity and EF variables also were examined.

RESULTS

Individuals with FXS demonstrated increased gamma band and reduced alpha band connectivity across all frontal regions and across hemispheres compared to TDC. After controlling for nonverbal IQ, increased error rates on EF tasks were associated with increased gamma band and reduced alpha band connectivity.

LIMITATIONS

Frontal connectivity findings are limited to intrinsic brain activity during rest and may not generalize to frontal connectivity during EF tasks or everyday function.

CONCLUSIONS

We report gamma hyper-connectivity and alpha hypo-connectivity within source-localized frontal brain regions in FXS compared to TDC during resting-state EEG. For the first time in FXS, we report significant associations between EF and altered frontal connectivity, with increased error rate relating to increased gamma band connectivity and reduced alpha band connectivity. These findings suggest increased phase connectivity within gamma band may impair EF performance, whereas greater alpha band connectivity may provide compensatory support for EF. Together, these findings provide important insight into neurophysiological mechanisms of EF deficits in FXS and provide novel targets for treatment development.

Study of the Interaction between Executive Function and Adaptive Behavior at School in Girls with Fragile X Syndrome

The aim of this research is to analyze the relationship between executive functions and adaptive behavior in girls with Fragile X syndrome (FXS) in the school setting. This study is part of a larger investigation conducted at the Hospital Parc Tauli in Sabadell. The sample consists of a total of 40 girls (26 with FXS and 14 control) aged 7–16 years, who were administered different neuropsychological tests (WISC-V, NEPSY-II, WCST, TOL) and questionnaires answered by teachers (ABAS-II, BRIEF 2, ADHD Rating Scale). The results show that there is a greater interaction between some areas of executive function (cognitive flexibility, auditory attention, and visual abstraction capacity) and certain areas of adaptive behavior (conceptual, practical, social, and total domains) in the FXS group than in the control group. These results suggest that an alteration in the executive functions was affecting the daily functioning of the girls with FXS to a greater extent.

Fragile X syndrome in young females: Influence of executive function on the neurocognitive profile and adaptive behavior

INTRODUCTION

The aim of this study is to describe the relationship between executive function (EF) and performance in different areas of the neurocognitive profile in young girls with Fragile-X-Syndrome (FXS).

METHOD

A neuropsychological assessment was carried out to 40 female participants aged 7-16 years (26 FXS, 14 control group).

RESULTS

Regarding intellectual ability, in the group of girls with FXS 3.84 % of the participants obtained IQ scores in the range of moderate ID (IQ 35-40 to 49), 46.15 % in the range of mild ID (IQ 50-70), 38.46 % in the borderline range (IQ 70-85), and 11.53 % within the average range (IQ > 85). EF was found to have a greater influence on adaptive behavior, arithmetic ability, theory of mind, leadership, social integration, social competence, and anxiety/shyness in the group with FXS.

CONCLUSIONS

In girls with FXS, EF showed a greater influence on adaptive behavior, arithmetic ability, and social domain.

Brain circuitry, behavior, and cognition: A randomized placebo-controlled trial of donepezil in fragile X syndrome

BACKGROUND

Fragile X syndrome, the most common inherited cause for intellectual disability, is associated with alterations in cholinergic among other neurotransmitter systems. This study investigated the effects of donepezil hydrochloride, a cholinesterase inhibitor that has potential to correct aberrant cholinergic signaling.

METHOD

Forty-two individuals with fragile X syndrome (mean age=19.61 years) were randomized to receive 2.5-10.0 mg of donepezil (n=20, seven females) or placebo (n=22, eight females) per day. One individual in the active group withdrew at week 7. Outcomes included the contingency naming test, the aberrant behavior checklist, and behavior and brain activation patterns during a functional magnetic resonance imaging gaze discrimination task.

RESULTS

There were no significant differences between active and placebo groups on cognitive (contingency naming task) or behavioral (total score or subscales of the aberrant behavior checklist) outcomes. At baseline, the active and placebo groups did not differ in functional magnetic resonance imaging activation patterns during the gaze task. After 12 weeks of treatment the active group displayed reduced activation in response to the averted vs direct gaze contrast, relative to the placebo group, in the left superior frontal gyrus.

CONCLUSIONS

Reduced functional brain activation for the active group may represent less arousal in response to direct eye gaze, relative to the placebo group. Change in functional magnetic resonance imaging activation patterns may serve as a more sensitive metric and predictor of response to treatment when compared to cognitive and behavioral assessments. Our results suggest that donepezil may have an impact on brain functioning, but longer term follow-up and concomitant behavioral intervention may be required to demonstrate improvement in cognition and behavior.

Clinical developmental, neuropsychological, and social-emotional features of Turner syndrome

Individuals with Turner syndrome (TS) are at risk for a constellation of neurocognitive and psychosocial differences, although there is significant individual variability in these features. TS is associated with an increased risk for difficulties with visual-spatial reasoning, visual-spatial memory, attention, executive functioning, motor, and math skills. Additionally, increased rates of social difficulties, anxiety, and depression are observed. There can be significant interplay between all of these factors contributing to the behavioral phenotype. Neuropsychological features and previous research are reviewed. Clinical considerations and recommendations for evaluation and treatment of psychological and behavioral difficulties are provided, including consideration of medical features in TS, as well as therapies, educational supports, and medication treatment. Future research is needed to evaluate effectiveness of different treatments for neuropsychological and psychosocial features of TS, including modification and validation of existing evidence-based treatments and new approaches to care.

Executive Function in Fragile X Syndrome: A Systematic Review

Executive function (EF) supports goal-directed behavior and includes key aspects such as working memory, inhibitory control, cognitive flexibility, attention, processing speed, and planning. Fragile X syndrome (FXS) is the leading inherited monogenic cause of intellectual disability and is phenotypically characterized by EF deficits beyond what is expected given general cognitive impairments. Yet, a systematic review of behavioral studies using performance-based measures is needed to provide a summary of EF deficits across domains in males and females with FXS, discuss clinical and biological correlates of these EF deficits, identify critical limitations in available research, and offer suggestions for future studies in this area. Ultimately, this review aims to advance our understanding of the underlying pathophysiological mechanisms contributing to EF in FXS and to inform the development of outcome measures of EF and identification of new treatment targets in FXS.

Developmental trajectories of executive functions in young males with fragile X syndrome

BACKGROUND

Executive functions (EF) have been identified as impaired in FXS, but few studies have examined their developmental trajectories.

AIMS

The primary aim of this longitudinal study was to examine the development of EF in young males with FXS compared to Mental Age (MA)-matched controls.

METHODS AND PROCEDURES

The sample comprised 56 boys with FXS (ages 7-13 years), and 48 MA-matched typical boys (ages 4-8 years). EF tasks included measures of inhibitory control, working memory, cognitive flexibility/set-shifting, problem solving/planning, and processing speed. Tasks were administered at three time points over five-years.

OUTCOMES AND RESULTS

The MA-Matched Typical boys significantly outperformed the FXS boys on all EF tasks, with the FXS Group showing a pattern of slow, but positive growth on most EF tasks. For working memory tasks, significant interactions were noted between MA and autism symptom severity, and MA and medication status. The probability of task completion increased with higher MA.

CONCLUSIONS AND IMPLICATIONS

These findings contribute to our understanding of the development of EF in this population. They also lay the foundation for use of EF tasks in treatment efforts, particularly with respect to documenting improvements and practice effects, and in understanding associations with targeted developmental outcomes.

Updated report on tools to measure outcomes of clinical trials in fragile X syndrome

OBJECTIVE

Fragile X syndrome (FXS) has been the neurodevelopmental disorder with the most active translation of preclinical breakthroughs into clinical trials. This process has led to a critical assessment of outcome measures, which resulted in a comprehensive review published in 2013. Nevertheless, the disappointing outcome of several recent phase III drug trials in FXS, and parallel efforts at evaluating behavioral endpoints for trials in autism spectrum disorder (ASD), has emphasized the need for re-assessing outcome measures and revising recommendations for FXS.

METHODS

After performing an extensive database search (PubMed, Food and Drug Administration (FDA)/National Institutes of Health (NIH)'s www.ClinicalTrials.gov, etc.) to determine progress since 2013, members of the Working Groups who published the 2013 Report evaluated the available outcome measures for FXS and related neurodevelopmental disorders using the COSMIN grading system of levels of evidence. The latter has also been applied to a British survey of endpoints for ASD. In addition, we also generated an informal classification of outcome measures for use in FXS intervention studies as instruments appropriate to detect shorter- or longer-term changes.

RESULTS

To date, a total of 22 double-blind controlled clinical trials in FXS have been identified through www.ClinicalTrials.gov and an extensive literature search. The vast majority of these FDA/NIH-registered clinical trials has been completed between 2008 and 2015 and has targeted the core excitatory/inhibitory imbalance present in FXS and other neurodevelopmental disorders. Limited data exist on reliability and validity for most tools used to measure cognitive, behavioral, and other problems in FXS in these trials and other studies. Overall, evidence for most tools supports a moderate tool quality grading. Data on sensitivity to treatment, currently under evaluation, could improve ratings for some cognitive and behavioral tools. Some progress has also been made at identifying promising biomarkers, mainly on blood-based and neurophysiological measures.

CONCLUSION

Despite the tangible progress in implementing clinical trials in FXS, the increasing data on measurement properties of endpoints, and the ongoing process of new tool development, the vast majority of outcome measures are at the moderate quality level with limited information on reliability, validity, and sensitivity to treatment. This situation is not unique to FXS, since reviews of endpoints for ASD have arrived at similar conclusions. These findings, in conjunction with the predominance of parent-based measures particularly in the behavioral domain, indicate that endpoint development in FXS needs to continue with an emphasis on more objective measures (observational, direct testing, biomarkers) that reflect meaningful improvements in quality of life. A major continuous challenge is the development of measurement tools concurrently with testing drug safety and efficacy in clinical trials.